import "@std/mem"
import "@std/arraylist"
import "@std/testing"
import "@source/diagnostics"
import "@source/strpool"
import "@source/lexer"
import "@source/parser"
import "@source/ast"
import "@source/ir"
import "@source/interpreter"
sema :: import "@source/sema"
typecheck :: import "@source/sema/check"

@hide:file
CompileError :: alias mem.AllocError | diagnostics.CapacityError | strpool.InternError | lexer.SourceError

# every consumer test executes only after all source and frontend storage is gone.
@hide:file
compile_owned proc(text []u8, diagnostic_store @mut diagnostics.Store) ir.Module ! CompileError {
    source :: try mem.alloc(u8, mem.c_allocator, text.len)
    defer mem.free(mem.c_allocator, source)
    for (text) |byte, i| source[i] = byte
    strings := strpool.init(mem.c_allocator)
    defer strpool.deinit(&strings)
    scan_state := lexer.init(mem.c_allocator)
    defer lexer.deinit(&scan_state)
    try lexer.scan(&scan_state, source, &strings, diagnostic_store)
    tree := try parser.parse(mem.c_allocator, scan_state.tokens.items, source, diagnostic_store)
    defer ast.deinit(&tree)
    resolution := try sema.resolve(mem.c_allocator, &tree, &strings, diagnostic_store)
    defer sema.deinit(&resolution)
    checked := try typecheck.check(mem.c_allocator, &tree, &resolution, diagnostic_store)
    defer typecheck.deinit(&checked)
    return try lower(mem.c_allocator, &tree, &resolution, &checked, diagnostic_store)
}

@hide:file
expect_trap proc(
    outcome interpreter.Outcome,
    diagnostic_store @diagnostics.Store,
    code diagnostics.Code,
) void ! testing.Error {
    if (outcome.trap) |id| {
        if (diagnostics.get(diagnostic_store, id)) |diagnostic| {
            try testing.expect_equal(code, diagnostic.code)
            return
        }
    }
    return .expectation_failed
}

executes_calls_locals_arithmetic_and_nested_argument_slices test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `add proc(left int, right int) int {
        `    result :: left + right
        `    return result
        `}
        `double proc(value int) int {
        `    return value * 2
        `}
        `main proc() int {
        `    a :: add(double(4), add(5, 6))
        `    b :: add(10, 13)
        `    return a + b
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.int, outcome.value.type)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

owns_decoded_strings_after_source_and_frontend_are_freed test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `text :: "a\\\"\n\r\t\0\x41\x7a"
        `identity proc(value string) string {
        `    return value
        `}
        `main proc() string {
        `    return identity(text)
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.string, outcome.value.type)
    try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.string), "a\\\"\n\r\t\x00Az"))
}

resolves_module_local_string_ids_after_frontend_cleanup test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned(
        "first :: \"not the result\"\nidentity proc(value string) string { return value }\nmain proc() string { return identity(\"second\\n\\x00\") }\n",
        &diagnostic_store,
    )
    defer ir.deinit(&module)
    outcome :: try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal([]u8, "second\n\x00", ir.string_bytes(&module, outcome.value.data.string))
}

honors_float_context_and_float_division test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `main proc() float {
        `    left :: 3
        `    return -(left / 2) + 2.0
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.float, outcome.value.type)
    try testing.expect_equal(f64(0.5), outcome.value.data.real)
}

executes_forward_lazy_globals_and_function_aliases test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `forward :: later + 1
        `forwarded :: add
        `later :: 18
        `add proc(left int, right int) int {
        `    local_alias :: forwarded
        `    return left + right
        `}
        `main proc() int {
        `    invoke :: forwarded
        `    return invoke(forward, 23)
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
    again := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&again)
    try testing.expect(again.trap == null)
    try testing.expect_equal(i64(42), again.value.data.integer)
}

supports_bare_void_value_returns_and_fallthrough test {
    sources [3][]u8 :: [
        "main proc() void {\n return\n}\n",
        "noop proc() void {}\nmain proc() void {\n return noop()\n}\n",
        "noop proc() void {}\nmain proc() void {\n noop()\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.void, outcome.value.type)
    }
}

constructs_present_optionals_without_losing_nested_null_or_repeating_values test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `next proc(calls @mut i16) i16 {
        `    calls^ = calls^ + 1
        `    return 42
        `}
        `nested proc() ??i16 { return some!(null) }
        `Box :: struct { values [2]i16 }
        `main proc() bool {
        `    calls i16 := 0
        `    absent ??i16 :: null
        `    present ??i16 :: nested()
        `    full ??i16 :: some!(some!(42))
        `    exact i16 :: 42
        `    value ?i16 :: some!(exact)
        `    once ?i16 :: some!(next(&calls))
        `    boxed ?Box :: some!(Box{ values = [20, 22] })
        `    pointer ?@i16 :: some!(&exact)
        `    nested_pointer ??@i16 :: some!(null)
        `    return (
        `        absent == null and present != null and present? == null
        `        and full != null and full? != null and full?? == 42
        `        and value? == 42 and once? == 42 and calls == 1
        `        and boxed?.values[0] + boxed?.values[1] == 42
        `        and pointer?^ == 42 and nested_pointer != null and nested_pointer? == null
        `    )
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.bool, outcome.value.type)
    try testing.expect(outcome.value.data.boolean)
}

rejects_some_without_optional_context_wrong_arity_and_inexact_payloads test {
    sources [6][]u8 :: [
        "main proc() ?i16 { return some!() }\n",
        "main proc() ?i16 { return some!(1, 2) }\n",
        "main proc() bool { return some!(true) }\n",
        "main proc() ?i16 { return some!(true) }\n",
        "main proc() ?i16 { value i32 :: 42\nreturn some!(value) }\n",
        "main proc() ?i16 { return some!(null) }\n",
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        code diagnostics.Code :: if (i < 2) .argument_count_mismatch else if (i == 2) .invalid_operand else .type_mismatch
        try expect_trap(outcome, &diagnostic_store, code)
    }
}

preserves_demanded_diagnostic_identity_and_source_location test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `bad proc() int {
        `    return unknown
        `}
        `main proc() int {
        `    before :: 1 + 2
        `    return bad()
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    diagnostic :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
    try testing.expect_equal(diagnostics.Code.unknown_name, diagnostic.code)
    try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], "unknown"))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
    try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
}

skips_unreachable_and_unused_invalid_code test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `bad proc() int {
        `    return unknown
        `}
        `unused :: "\q"
        `main proc() int {
        `    return 42
        `    9223372036854775807 + 1
        `    missing
        `    huge :: 9223372036854775808
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect(diagnostics.count(&diagnostic_store) > 0)
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

traps_local_forward_loads_and_global_initialization_cycles test {
    sources [3][]u8 :: [
        "main proc() int {\n before :: after\n after :: 42\n return before\n}\n",
        "left int :: right\nright int :: left\nmain proc() int {\n return left\n}\n",
        "self int :: self\nmain proc() int {\n return self\n}\n",
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        code diagnostics.Code :: if (i == 0) .read_before_initialization else .initialization_cycle
        try expect_trap(outcome, &diagnostic_store, code)
    }
}

handles_integer_boundaries_without_host_overflow test {
    sources [3][]u8 :: [
        "main proc() int {\n return 9223372036854775807\n}\n",
        "main proc() int {\n return -9223372036854775808\n}\n",
        "main proc() int {\n return -0009223372036854775808\n}\n",
    ]
    expected [3]i64 :: [maxval!(i64), minval!(i64), minval!(i64)]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected[i], outcome.value.data.integer)
    }
}

traps_invalid_literals_escapes_and_checked_integer_arithmetic test {
    sources [8][]u8 :: [
        "main proc() int {\n return 9223372036854775808\n}\n",
        "main proc() int {\n return -9223372036854775809\n}\n",
        "main proc() int {\n return 9223372036854775807 + 1\n}\n",
        "main proc() int {\n return -(-9223372036854775808)\n}\n",
        "main proc() int {\n return -9223372036854775808 - 1\n}\n",
        "main proc() int {\n return 9223372036854775807 * 2\n}\n",
        "main proc() string {\n return \"\\q\"\n}\n",
        "main proc() string {\n return \"\\x0g\"\n}\n",
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        code := diagnostics.Code.integer_overflow
        if (i < 2) code = .literal_out_of_range
        if (i >= 6) code = .invalid_escape
        try expect_trap(outcome, &diagnostic_store, code)
    }
}

validates_main_and_preserves_first_declaration test {
    sources [4][]u8 :: [
        "other proc() void {}\n",
        "main :: 42\n",
        "main proc(value int) int {\n return value\n}\n",
        "main proc() int {\n return 42\n}\nmain proc() int {\n return 7\n}\n",
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (i == 3) {
            try testing.expect(outcome.trap == null)
            try testing.expect_equal(i64(42), outcome.value.data.integer)
        } else {
            code diagnostics.Code :: if (i == 0) .missing_entry else .invalid_entry
            try expect_trap(outcome, &diagnostic_store, code)
            try testing.expect_equal(module.entry_diagnostic, outcome.trap?)
        }
    }
}

invalid_signatures_trap_without_poisoning_unrelated_main test {
    sources [2][]u8 :: [
        "broken proc(value void) void {}\nmain proc() int {\n return 42\n}\n",
        "main proc() Unknown {\n return 42\n}\n",
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect(diagnostics.count(&diagnostic_store) > 0)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (i == 0) {
            try testing.expect(outcome.trap == null)
            try testing.expect_equal(i64(42), outcome.value.data.integer)
        } else {
            try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
            try expect_trap(outcome, &diagnostic_store, .unknown_name)
        }
    }
}

parses_float_context_without_integer_range_limits_and_rejects_float_overflow test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned(
        "main proc() float {\n return 18446744073709551616\n}\n",
        &diagnostic_store,
    )
    defer ir.deinit(&module)
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.float, outcome.value.type)
    try testing.expect_equal(f64(18446744073709551616.0), outcome.value.data.real)
    source := arraylist.init(u8, mem.c_allocator)
    defer arraylist.deinit(&source)
    for ("main proc() float {\n return ") |byte| try arraylist.append(&source, byte)
    for (usize(0)..usize(400)) |_| try arraylist.append(&source, '9')
    for (".0\n}\n") |byte| try arraylist.append(&source, byte)
    oversized := try compile_owned(source.items, &diagnostic_store)
    defer ir.deinit(&oversized)
    trapped := try interpreter.run(mem.c_allocator, &oversized, &diagnostic_store)
    defer interpreter.deinit(&trapped)
    try expect_trap(trapped, &diagnostic_store, .literal_out_of_range)
}

rejects_inexact_integer_literals_in_float_context test {
    sources [4][]u8 :: [
        "main proc() f64 {\n return 9007199254740993\n}\n",
        "main proc() f64 {\n value :: 9007199254740993\n return value\n}\n",
        "main proc() f64 {\n return 9007199254740993 / 1\n}\n",
        "main proc() f64 {\n values [1]f64 :: [9007199254740993]\n return values[0]\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .inexact_integer_literal)
    }
}

preserves_exact_large_integers_and_explicit_float_rounding test {
    sources [3][]u8 :: [
        "main proc() f64 {\n return 9007199254740994 - 9007199254740992\n}\n",
        "main proc() f64 {\n return 9007199254740993.0 - 9007199254740992\n}\n",
        "main proc() f64 {\n return 0003\n}\n",
    ]
    expected [3]f64 :: [2, 0, 3]
    for sources |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected[i], outcome.value.data.real)
    }
}

accepts_representable_subnormals_and_rejects_underflow_to_zero test {
    zeros [2]usize :: [307, 400]
    for (zeros) |count| {
        source := arraylist.init(u8, mem.c_allocator)
        defer arraylist.deinit(&source)
        for ("main proc() float {\n return 0.") |byte| try arraylist.append(&source, byte)
        for (usize(0)..count) |_| try arraylist.append(&source, '0')
        for ("1\n}\n") |byte| try arraylist.append(&source, byte)
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source.items, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (count == 307) {
            try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
            try testing.expect(outcome.trap == null)
            try testing.expect_equal(ir.Type.float, outcome.value.type)
            try testing.expect(outcome.value.data.real > 0 and outcome.value.data.real < 1)
        } else {
            try expect_trap(outcome, &diagnostic_store, .literal_out_of_range)
        }
    }
}

@hide:file
AllocationState :: struct {
    remaining usize
    live usize = 0
}

@hide:file
limited_alloc proc(context ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
    if (context) |userdata| {
        state @mut AllocationState :: ptrcast!(userdata)
        if (state.remaining == 0) return null
        state.remaining -= 1
        memory :: mem.raw_alloc(mem.c_allocator, size, alignment)
        if (memory) |_| state.live += 1
        return memory
    }
    unreachable
}

@hide:file
limited_realloc proc(context ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
    if (context) |userdata| {
        state @mut AllocationState :: ptrcast!(userdata)
        if (state.remaining == 0) return null
        state.remaining -= 1
        resized :: mem.raw_realloc(mem.c_allocator, memory, old_size, new_size, alignment)
        if (resized) |_| {
            if (memory) |_| {} else state.live += 1
        }
        return resized
    }
    unreachable
}

@hide:file
limited_free proc(context ?@mut anyopaque, memory ?*mut u8, size usize, alignment usize) void {
    if (context) |userdata| {
        state @mut AllocationState :: ptrcast!(userdata)
        if (memory) |_| state.live -= 1
        mem.raw_free(mem.c_allocator, memory, size, alignment)
        return
    }
    unreachable
}

@hide:file
limited_vtable :: mem.AllocatorVTable{ alloc = limited_alloc, realloc = limited_realloc, free = limited_free }

releases_temporaries_and_partially_owned_modules_on_allocation_failure test {
    strings := strpool.init(mem.c_allocator)
    defer strpool.deinit(&strings)
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `text :: "owned\nstring"
        `factor float :: 3.5
        `enabled :: true or false and false
        `compose proc(left bool, right bool) bool {
        `    return left and right
        `}
        `broken proc() bool {
        `    return compose(true and absent, false or true)
        `}
        `identity proc(value string) string {
        `    if false {
        `        return value
        `    }
        `    local :: value
        `    return local
        `}
        `rows proc(value [2][2]string) [2][2]string { return value }
        `main proc() string {
        `    computed float :: factor * 2
        `    aggregate :: rows([[text, "second"], ["third", text]])
        `    (aggregate[1])[1]
        `    remaining := 2
        `    for 0..=2 |item| {
        `        saved :: identity(text)
        `        for 0..2 |_| {
        `            nested :: identity(saved)
        `            identity(nested)
        `            if (item == 1) continue else break
        `        }
        `        if (item < 2) continue else break
        `    }
        `    while compose(remaining > 0 and enabled, compose(!false, compose(true or false, compose(true, compose(true, true))))) {
        `        pass :: identity(text)
        `        identity(pass)
        `        remaining = remaining - 1
        `        inner := 2
        `        while inner > 0 {
        `            inner = inner - 1
        `            if (inner > 0) continue else break
        `        }
        `        if (remaining > 0) continue else break
        `    }
        `    if computed > 0 and (enabled or false) {
        `        saved :: identity(text)
        `        if computed < 10 {
        `            return saved
        `        }
        `    } else {
        `        fallback :: "fallback"
        `        identity(fallback)
        `    }
        `    return identity(text)
        `}
    scan_state := lexer.init(mem.c_allocator)
    defer lexer.deinit(&scan_state)
    try lexer.scan(&scan_state, source, &strings, &diagnostic_store)
    tree := try parser.parse(mem.c_allocator, scan_state.tokens.items, source, &diagnostic_store)
    defer ast.deinit(&tree)
    resolution := try sema.resolve(mem.c_allocator, &tree, &strings, &diagnostic_store)
    defer sema.deinit(&resolution)
    checked := try typecheck.check(mem.c_allocator, &tree, &resolution, &diagnostic_store)
    defer typecheck.deinit(&checked)
    succeeded := false
    failures := usize(0)
    for (usize(0)..usize(512)) |limit| {
        state := AllocationState{ remaining = limit }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        module := lower(allocator, &tree, &resolution, &checked, &diagnostic_store) catch |error| {
            try testing.expect(error == .out_of_memory)
            failures += 1
            try testing.expect_equal(usize(0), state.live)
            continue
        }
        errdefer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.string), "owned\nstring"))
        interpreter.deinit(&outcome)
        ir.deinit(&module)
        try testing.expect_equal(usize(0), state.live)
        succeeded = true
        break
    }
    try testing.expect(succeeded)
    try testing.expect(failures > 0)
}

recursive_factorial_and_conditional_returns_execute_after_frontend_cleanup test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `factorial proc(n int) int {
        `    if n <= 1 {
        `        return 1
        `    } else {
        `        return n * factorial(n - 1)
        `    }
        `}
        `main proc() int {
        `    return factorial(5)
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(120), outcome.value.data.integer)
}

nested_branches_joins_calls_and_lazy_globals_preserve_execution_position test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `seed :: classify(2)
        `enabled bool :: true
        `identity proc(value int) int { return value }
        `classify proc(n int) int {
        `    if n < 0 {
        `        return 3
        `    } else if n == 0 {
        `        return 5
        `    } else {
        `        if n > 1 {
        `            local :: identity(7)
        `            identity(local)
        `        } else {
        `            local :: identity(9)
        `            identity(local)
        `        }
        `        return identity(11)
        `    }
        `}
        `choose proc(flag bool) int {
        `    if flag {
        `        local :: identity(seed)
        `        identity(local)
        `    } else {
        `        local :: identity(13)
        `        identity(local)
        `    }
        `    return identity(seed) + classify(0) + classify(-1)
        `}
        `main proc() int {
        `    return choose(enabled) + choose(false) + classify(1) - 7
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

bool_storage_results_and_numeric_comparisons_execute test {
    sources [16][]u8 :: [
        "main proc() bool { return 2 == 2 }\n",
        "main proc() bool { return 2 != 3 }\n",
        "main proc() bool { return -2 < 1 }\n",
        "main proc() bool { return 2 <= 2 }\n",
        "main proc() bool { return 3 > 2 }\n",
        "main proc() bool { return 2 >= 2 }\n",
        "main proc() bool { return 2 == 2.0 }\n",
        "main proc() bool { return 2 != 3.0 }\n",
        "main proc() bool { return 2 < 2.5 }\n",
        "main proc() bool { return 2 <= 2.0 }\n",
        "main proc() bool { return 3 > 2.5 }\n",
        "main proc() bool { return 2 >= 2.0 }\n",
        "main proc() bool { return true == true }\n",
        "main proc() bool { return false != true }\n",
        "flag bool :: false\nidentity proc(value bool) bool { return value }\nmain proc() bool {\n local bool :: identity(flag)\n return identity(local == false)\n}\n",
        "main proc() bool {\n local :: 2\n return local < 2.5\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.bool, outcome.value.type)
        try testing.expect(outcome.value.data.boolean)
    }
}

conditional_errors_trap_only_when_demanded_and_preserve_original_identity test {
    sources [7][]u8 :: [
        "main proc() int {\n if true {\n return 42\n } else {\n return unknown\n }\n}\n",
        "main proc() int {\n if false {\n return 42\n } else {\n return unknown\n }\n}\n",
        "main proc() int {\n if true {\n return 42\n }\n}\n",
        "main proc() int {\n if false {\n return 42\n }\n}\n",
        "main proc() void {\n if false {\n unknown\n }\n}\n",
        "main proc() int {\n if 1 {\n return 42\n } else {\n return 0\n }\n}\n",
        "main proc() int {\n if unknown {\n return 42\n }\n}\n",
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (index == 0 or index == 2 or index == 4) {
            try testing.expect(outcome.trap == null)
            if (index == 4) try testing.expect_equal(ir.Type.void, outcome.value.type)
            else try testing.expect_equal(i64(42), outcome.value.data.integer)
        } else {
            try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
            code := diagnostics.Code.unknown_name
            if (index == 3) code = .missing_return
            if (index == 5) code = .condition_not_bool
            try testing.expect_equal(code, original.code)
            if (index == 5) try testing.expect(mem.eql(source[usize(original.span.start)..usize(original.span.end)], "1"))
        }
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

missing_return_does_not_replace_reached_arm_error test {
    sources [3][]u8 :: [
        "main proc() int {\n if true {\n return unknown\n }\n}\n",
        "main proc() int {\n if false {\n return unknown\n }\n}\n",
        "main proc() int {\n if false {\n return unknown\n }\n return 42\n}\n",
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (index == 2) {
            try testing.expect(outcome.trap == null)
            try testing.expect_equal(i64(42), outcome.value.data.integer)
        } else {
            code diagnostics.Code :: if (index == 0) .unknown_name else .missing_return
            try expect_trap(outcome, &diagnostic_store, code)
            for (0..diagnostics.count(&diagnostic_store)) |i| {
                diagnostic :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(i))?
                if (diagnostic.code == code) try testing.expect_equal(diagnostics.DiagnosticId(i), outcome.trap?)
            }
        }
    }
}

nested_locals_are_predeclared_before_any_arm_executes test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `main proc() int {
        `    if true {
        `        if true {
        `            before :: later
        `            later :: 42
        `            return before
        `        }
        `    }
        `    return 0
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try expect_trap(outcome, &diagnostic_store, .read_before_initialization)
}

iterative_factorial_executes_from_owned_ir_after_frontend_cleanup test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `factorial proc(n int) int {
        `    remaining := n
        `    result := 1
        `    while remaining > 1 {
        `        result = result * remaining
        `        remaining = remaining - 1
        `    }
        `    return result
        `}
        `main proc() int {
        `    return factorial(5)
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.int, outcome.value.type)
    try testing.expect_equal(i64(120), outcome.value.data.integer)
}

zero_nested_early_return_and_predicate_call_loops_execute test {
    sources [6][]u8 :: [
        "main proc() int {\n n := 0\n while n > 0 {\n n = n - 1\n }\n return 42 + n\n}\n",
        "main proc() int {\n outer := 3\n total := 0\n while outer > 0 {\n inner := 2\n while inner > 0 {\n total = total + 7\n inner = inner - 1\n }\n outer = outer - 1\n }\n return total\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n if n == 1 { return 42 }\n n = n - 1\n }\n return 0\n}\n",
        "enabled :: positive(1)\npositive proc(n int) bool { return n > 0 }\nmain proc() int {\n n := 3\n total := 0\n while positive(n) {\n if enabled { total = total + 14 }\n n = n - 1\n }\n return total\n}\n",
        "main proc() int {\n n := 0\n while (n < 42) n = n + 1\n return n\n}\n",
        "main proc() int {\n while true { return 42 }\n return 0\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.int, outcome.value.type)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
    }
}

float_bool_string_and_compatible_function_updates_execute test {
    sources [4][]u8 :: [
        "main proc() float {\n value float := 0\n value = 3 / 2\n return value\n}\n",
        "main proc() bool {\n flag := false\n flag = true\n return flag\n}\n",
        "main proc() string {\n text := \"before\"\n text = \"owned\\nupdated\"\n return text\n}\n",
        "first proc(value int) int { return value + 1 }\nsecond proc(renamed int) int { return renamed + 2 }\nmain proc() int {\n invoke := first\n invoke = second\n return invoke(40)\n}\n",
    ]
    expected_types [4]ir.Type :: [.float, .bool, .string, .int]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected_types[index], outcome.value.type)
        match index {
            0: try testing.expect_equal(f64(1.5), outcome.value.data.real)
            1: try testing.expect(outcome.value.data.boolean)
            2: try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.string), "owned\nupdated"))
            3: try testing.expect_equal(i64(42), outcome.value.data.integer)
            else: unreachable
        }
    }
}

forward_assignments_check_initialization_after_evaluating_the_rhs test {
    sources [2][]u8 :: [
        "main proc() int {\n later = 42\n later := 0\n return later\n}\n",
        "main proc() int {\n later = later + 1\n later := 0\n return later\n}\n",
    ]
    codes [2]diagnostics.Code :: [.write_before_initialization, .read_before_initialization]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
        diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
        try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], "later"))
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

loop_and_reentered_arm_locals_are_uninitialized_before_later_declarations test {
    sources [11][]u8 :: [
        "main proc() int {\n n := 2\n while n > 0 {\n if n == 1 { return later }\n later :: 42\n n = n - 1\n }\n return 0\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n if n == 1 {\n later = 42\n return later\n }\n later := 0\n n = n - 1\n }\n return 0\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n if true {\n if n == 1 { return later }\n later :: 42\n }\n n = n - 1\n }\n return 0\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n if true {\n if n == 1 {\n later = 42\n return later\n }\n later := 0\n }\n n = n - 1\n }\n return 0\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n if false {} else {\n if n == 1 { return later }\n later :: 42\n }\n n = n - 1\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if n == 0 { return later }\n if (n == 1) continue\n later :: 42\n continue\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if n == 0 { later = 42 }\n if (n == 1) continue\n later := 0\n continue\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if true {\n if n == 0 { return later }\n if (n == 1) continue\n later :: 42\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if true {\n if n == 0 { later = 42 }\n if (n == 1) continue\n later := 0\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if false {} else {\n if n == 0 { return later }\n if (n == 1) continue\n later :: 42\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n n := 3\n while n > 0 {\n n = n - 1\n if false {} else {\n if n == 0 { later = 42 }\n if (n == 1) continue\n later := 0\n continue\n }\n }\n return 0\n}\n",
    ]
    codes [11]diagnostics.Code :: [
        .read_before_initialization, .write_before_initialization,
        .read_before_initialization, .write_before_initialization, .read_before_initialization,
        .read_before_initialization, .write_before_initialization,
        .read_before_initialization, .write_before_initialization,
        .read_before_initialization, .write_before_initialization,
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
        diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
        try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], "later"))
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

invalid_assignments_and_loop_conditions_preserve_original_diagnostics test {
    sources [9][]u8 :: [
        "main proc() int {\n value :: 0\n value = 1\n return 42\n}\n",
        "update proc(value int) int {\n value = 1\n return value\n}\nmain proc() int { return update(0) }\n",
        "value := 0\nmain proc() int {\n value = 1\n return value\n}\n",
        "main proc() int {\n unknown = 1\n return 42\n}\n",
        "main proc() int {\n value := 0\n value = unknown\n return value\n}\n",
        "main proc() int {\n value := 0\n value = 1.5\n return value\n}\n",
        "first proc(value int) int { return value }\nsecond proc(value bool) int { return 42 }\nmain proc() int {\n invoke := first\n invoke = second\n return 42\n}\n",
        "main proc() int {\n while 1 { return 42 }\n return 0\n}\n",
        "main proc() int {\n while unknown { return 42 }\n return 0\n}\n",
    ]
    codes [9]diagnostics.Code :: [.invalid_assignment_target, .invalid_assignment_target, .invalid_assignment_target, .unknown_name, .unknown_name, .type_mismatch, .type_mismatch, .condition_not_bool, .unknown_name]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        try testing.expect_equal(codes[index], original.code)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

zero_iteration_body_errors_are_checked_but_not_executed test {
    sources [5][]u8 :: [
        "main proc() int {\n while false {\n unknown = 1\n }\n return 42\n}\n",
        "main proc() int {\n while false {\n value :: 0\n value = 1\n }\n return 42\n}\n",
        "main proc() int {\n while false {\n value := 0\n value = true\n }\n return 42\n}\n",
        "main proc() int {\n while false {\n return unknown\n }\n return 42\n}\n",
        "main proc() int {\n while false {\n while unknown {}\n }\n return 42\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect(diagnostics.count(&diagnostic_store) > 0)
        count :: diagnostics.count(&diagnostic_store)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
        try testing.expect_equal(count, diagnostics.count(&diagnostic_store))
    }
}

terminal_true_loops_and_assignment_arithmetic_preserve_runtime_behavior test {
    sources [5][]u8 :: [
        "main proc() int {\n while true { return 42 }\n}\n",
        "main proc() int {\n while false { return 42 }\n}\n",
        "main proc() int {\n value := 9223372036854775807\n while true {\n value = value + 1\n return value\n }\n return 0\n}\n",
        "main proc() int {\n while true { break }\n}\n",
        "main proc() int {\n while false { continue }\n}\n",
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        if (index != 0 and index != 2) {
            try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
            diagnostic :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
            try testing.expect_equal(diagnostics.Code.missing_return, diagnostic.code)
        } else try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        if (index == 0) {
            try testing.expect(outcome.trap == null)
            try testing.expect_equal(i64(42), outcome.value.data.integer)
        } else {
            code diagnostics.Code :: if (index == 2) .integer_overflow else .missing_return
            try expect_trap(outcome, &diagnostic_store, code)
            if (index != 2) try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        }
    }
}

bounded_pure_loops_do_not_allocate_per_iteration_and_release_runtime_storage test {
    sources [2][]u8 :: [
        "main proc() int {\n n := 0\n while (n < 1 and !(n == 1)) or false {\n local :: n\n n = local + 1\n if (n == 1) break\n continue\n later :: 0\n }\n return n\n}\n",
        "main proc() int {\n n := 0\n while (n < 10000 and !(n == 10000)) or false {\n local :: n\n n = local + 1\n if (n == 10000) break\n continue\n later :: 0\n }\n return n\n}\n",
    ]
    expected [2]i64 :: [1, 10000]
    allocations := usize(0)
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        state := AllocationState{ remaining = 64 }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := try interpreter.run(allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected[index], outcome.value.data.integer)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        if (index == 0) allocations = usize(64) - state.remaining
        else try testing.expect_equal(allocations, usize(64) - state.remaining)
    }
}

boolean_truth_tables_nesting_negation_and_precedence_execute test {
    sources [18][]u8 :: [
        "main proc() bool { return false and false }\n",
        "main proc() bool { return false and true }\n",
        "main proc() bool { return true and false }\n",
        "main proc() bool { return true and true }\n",
        "main proc() bool { return false or false }\n",
        "main proc() bool { return false or true }\n",
        "main proc() bool { return true or false }\n",
        "main proc() bool { return true or true }\n",
        "main proc() bool { return !false }\n",
        "main proc() bool { return !true }\n",
        "main proc() bool { return !!true }\n",
        "main proc() bool { return !!!true }\n",
        "main proc() bool { return true or false and false }\n",
        "main proc() bool { return (true or false) and false }\n",
        "main proc() bool { return !(1 + 2 < 3) and 4 == 4 or false }\n",
        "main proc() bool { return false or (true and (false or !false)) }\n",
        "main proc() bool { return true and false or true and true }\n",
        "main proc() bool { return !(-9223372036854775808 < 0) }\n",
    ]
    expected [18]bool :: [
        false, false, false, true, false, true, true, true,
        true, false, true, false, true, false, true, true, true, false,
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.bool, outcome.value.type)
        try testing.expect_equal(expected[index], outcome.value.data.boolean)
    }
}

branchful_calls_preserve_earlier_temps_nested_arguments_and_function_callees test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `integer proc(value int) int { return value }
        `boolean proc(value bool) bool { return value }
        `score proc(first int, left bool, right bool, last int) int {
        `    if left and right { return first + last }
        `    return 0
        `}
        `invoke :: score
        `main proc() int {
        `    local :: invoke
        `    return local(integer(20), boolean(false or true), boolean(true and (false or true)), local(integer(0), false or boolean(true), true and !false, local(integer(5), true or false, true and true, integer(17))))
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

short_circuit_source_errors_remain_checked_but_skipped_in_every_consumer test {
    sources [10][]u8 :: [
        "main proc() bool { return false and absent or true }\n",
        "main proc() bool { return true or 1 }\n",
        "main proc() bool { return !(false and absent) }\n",
        "main proc() bool { return (false and absent) == false }\n",
        "flag :: true or absent\nmain proc() bool { return flag }\n",
        "main proc() bool {\n flag :: true or absent\n return flag\n}\n",
        "main proc() bool {\n flag := false\n flag = true or absent\n return flag\n}\n",
        "identity proc(value bool) bool { return value }\nmain proc() bool { return identity(true or absent) }\n",
        "main proc() bool {\n if true or absent { return true }\n return false\n}\n",
        "main proc() bool {\n true or absent\n while false and absent {}\n return true\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        count :: diagnostics.count(&diagnostic_store)
        try testing.expect(count > 0)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.bool, outcome.value.type)
        try testing.expect(outcome.value.data.boolean)
        try testing.expect_equal(count, diagnostics.count(&diagnostic_store))
    }
}

demanded_boolean_source_errors_keep_the_original_diagnostic_and_operand_span test {
    sources [8][]u8 :: [
        "main proc() bool { return true and absent }\n",
        "main proc() bool { return false or absent }\n",
        "main proc() bool { return true and 1 }\n",
        "main proc() bool { return false or 1 }\n",
        "main proc() bool { return !1 }\n",
        "main proc() bool { return !absent }\n",
        "main proc() bool { return absent and false }\n",
        "main proc() bool { return absent or true }\n",
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        code diagnostics.Code :: if (index >= 2 and index <= 4) .invalid_operand else .unknown_name
        operand []u8 :: if (index >= 2 and index <= 4) "1" else "absent"
        try testing.expect_equal(code, original.code)
        try testing.expect(mem.eql(source[usize(original.span.start)..usize(original.span.end)], operand))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

branchful_call_arguments_evaluate_left_to_right_before_later_errors test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `both proc(left bool, right bool) bool { return left and right }
        `main proc() bool {
        `    return both(false or (true and first_absent), true and second_absent)
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(2, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    original :: diagnostics.get(&diagnostic_store, outcome.trap?)?
    try testing.expect_equal(diagnostics.Code.unknown_name, original.code)
    try testing.expect(mem.eql(source[usize(original.span.start)..usize(original.span.end)], "first_absent"))
    try testing.expect_equal(2, diagnostics.count(&diagnostic_store))
}

short_circuit_protects_uninitialized_reads_global_cycles_and_overflow test {
    sources [6][]u8 :: [
        "main proc() bool {\n before :: false and later\n later :: true\n return !before\n}\n",
        "main proc() bool {\n before :: true or later\n later :: false\n return before\n}\n",
        "flag bool :: true or flag\nmain proc() bool { return flag }\n",
        "left bool :: false and right\nright bool :: left\nmain proc() bool { return !left }\n",
        "main proc() bool { return !(false and 9223372036854775807 + 1 == 0) }\n",
        "main proc() bool { return true or -(-9223372036854775808) == 0 }\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect(outcome.value.data.boolean)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    }
}

demanded_boolean_runtime_errors_keep_the_instruction_span test {
    sources [4][]u8 :: [
        "main proc() bool {\n before :: true and later\n later :: true\n return before\n}\n",
        "flag bool :: false or flag\nmain proc() bool { return flag }\n",
        "main proc() bool { return true and 9223372036854775807 + 1 == 0 }\n",
        "main proc() bool {\n minimum :: -9223372036854775808\n return false or -minimum == 0\n}\n",
    ]
    codes [4]diagnostics.Code :: [.read_before_initialization, .initialization_cycle, .integer_overflow, .integer_overflow]
    spans [4][]u8 :: ["later", "flag", "9223372036854775807 + 1", "-minimum"]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
        diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
        try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], spans[index]))
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

composed_loop_guards_recompute_and_overwrite_synthetic_results test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `enabled :: false or true and !false
        `positive proc(n int) bool { return n > 0 }
        `main proc() int {
        `    n := 4
        `    total := 0
        `    while (enabled and positive(n)) or n > 4 {
        `        if (n == 4 or n == 2) and !(n == 3) {
        `            total = total + 21
        `        }
        `        n = n - 1
        `    }
        `    return total + n
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

lazy_branchful_global_initializers_and_calls_release_every_runtime_allocation test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `first :: true and later
        `later :: false or !false
        `both proc(left bool, right bool) bool { return left and right }
        `bound proc(flag bool, value int) int {
        `    if flag { return value }
        `    return 0
        `}
        `main proc() bool {
        `    n := 3
        `    for bound(first or false, 0)..bound(both(first, true and later), 3) |i| {
        `        local :: both(first and first, later or false)
        `        if (local and i < 2) continue else break
        `    }
        `    while both(first and first, both(false or later, !false and later)) and n > 0 {
        `        n = n - 1
        `        if (n > 0) continue else break
        `    }
        `    return both(first and first, both(false or later, !false and later))
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    failures := usize(0)
    succeeded := false
    for (usize(0)..usize(64)) |limit| {
        state := AllocationState{ remaining = limit }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := interpreter.run(allocator, &module, &diagnostic_store) catch |error| {
            try testing.expect(error == .out_of_memory)
            failures += 1
            try testing.expect_equal(usize(0), state.live)
            continue
        }
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect(outcome.value.data.boolean)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        succeeded = true
        break
    }
    try testing.expect(succeeded)
    try testing.expect(failures > 0)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
}

skipped_rhs_does_not_hide_a_demanded_outer_type_mismatch test {
    sources [3][]u8 :: [
        "main proc() int { return true or absent }\n",
        "main proc() void {\n number := 0\n number = true or absent\n}\n",
        "integer proc(value int) int { return value }\nmain proc() int { return integer(true or absent) }\n",
    ]
    codes [3]diagnostics.Code :: [.return_type_mismatch, .type_mismatch, .type_mismatch]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        count :: diagnostics.count(&diagnostic_store)
        try testing.expect_equal(2, count)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
        try testing.expect_equal(count, diagnostics.count(&diagnostic_store))
    }
}

break_and_continue_skip_iterations_exit_early_and_restore_outer_targets test {
    sources [3][]u8 :: [
        "main proc() int {\n n := 0\n total := 0\n while n < 10 {\n n = n + 1\n if (n == 2 or n == 4) continue\n if (n == 6) break\n total = total + n\n }\n return total + 33\n}\n",
        "main proc() int {\n outer := 3\n total := 0\n while outer > 0 {\n outer = outer - 1\n inner := 3\n while inner > 0 {\n inner = inner - 1\n if (inner == 1) continue\n if (inner == 0) break\n total = total + 7\n }\n if (outer > 0) continue else break\n }\n return total + 21\n}\n",
        "main proc() int {\n n := 0\n while n < 5 {\n n = n + 1\n if (n < 3) continue else break\n n = n + 100\n }\n return n + 39\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
    }
}

continue_restarts_composed_calling_guards_after_branchful_body_calls test {
    guards [3][]u8 :: [
        "(positive(3 - n) and !(n == 2)) or n == 2",
        "!(n >= 3) and (positive(3 - n) or false)",
        "positive(3 - n) and ((n < 3 or false) and !false)",
    ]
    for (guards) |guard| {
        source := arraylist.init(u8, mem.c_allocator)
        defer arraylist.deinit(&source)
        for ("positive proc(n int) bool { return n > 0 }\nadvance proc(flag bool, n int) int {\n if flag { return n + 1 }\n return n + 1\n}\nmain proc() int {\n n := 0\n while ") |byte| try arraylist.append(&source, byte)
        for (guard) |byte| try arraylist.append(&source, byte)
        # bound a stale guard too, so incorrect continue lowering fails instead of hanging.
        for (" {\n n = advance(n == 0 or n == 1, n)\n if (n > 5) break\n continue\n n = n + 100\n }\n return n + 39\n}\n") |byte| try arraylist.append(&source, byte)
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source.items, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
    }
}

reached_outside_controls_preserve_diagnostic_identity_and_keyword_span test {
    sources [4][]u8 :: [
        "main proc() int {\n break\n return 42\n}\n",
        "main proc() int {\n continue\n return 42\n}\n",
        "bad proc() void {\n break\n}\nmain proc() int {\n while true { bad()\n break }\n return 42\n}\n",
        "main proc() int {\n while true { break }\n continue\n return 42\n}\n",
    ]
    codes [4]diagnostics.Code :: [.break_outside_loop, .continue_outside_loop, .break_outside_loop, .continue_outside_loop]
    keywords [4][]u8 :: ["break", "continue", "break", "continue"]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        try testing.expect_equal(codes[index], original.code)
        try testing.expect(mem.eql(source[usize(original.span.start)..usize(original.span.end)], keywords[index]))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

untaken_outside_controls_remain_checked_without_trapping test {
    sources [5][]u8 :: [
        "main proc() int {\n if (false) break\n return 42\n}\n",
        "main proc() int {\n if true { return 42 } else continue\n}\n",
        "main proc() int {\n return 42\n break\n}\n",
        "main proc() int {\n return 42\n continue\n}\n",
        "bad proc() void {\n continue\n}\nmain proc() int {\n while false { bad() }\n return 42\n}\n",
    ]
    codes [5]diagnostics.Code :: [.break_outside_loop, .continue_outside_loop, .break_outside_loop, .continue_outside_loop, .continue_outside_loop]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        try testing.expect_equal(codes[index], original.code)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

source_errors_after_loop_transfers_stay_checked_but_unreached test {
    sources [4][]u8 :: [
        "main proc() int {\n n := 2\n while n > 0 {\n n = n - 1\n continue\n missing\n }\n return 42\n}\n",
        "main proc() int {\n while true {\n break\n missing\n }\n return 42\n}\n",
        "main proc() int {\n n := 2\n while n > 0 {\n n = n - 1\n if (n > 0) continue else break\n missing\n }\n return 42\n}\n",
        "main proc() int {\n while true {\n return 42\n break\n continue\n missing\n }\n return 0\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        try testing.expect_equal(diagnostics.Code.unknown_name, original.code)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

traps_before_loop_controls_keep_the_original_error test {
    sources [2][]u8 :: [
        "main proc() int {\n while true {\n missing\n break\n }\n return 42\n}\n",
        "main proc() int {\n while true {\n missing\n continue\n }\n return 42\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .unknown_name)
        try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

owned_integer_ranges_execute_exclusive_inclusive_empty_signed_and_discard_forms test {
    sources [13][]u8 :: [
        "main proc() int {\n sum := 0\n for 0..7 |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n sum := 0\n for (0..=6) |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n sum := 0\n for (-3)..3 |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n sum := 0\n for (-3)..=3 |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n sum := 0\n for 7..7 |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n sum := 0\n for 7..=7 |i| { sum = sum + i }\n return sum\n}\n",
        "main proc() int {\n count := 0\n for 7..2 |_| { count = count + 1 }\n for 7..=2 |_| { count = count + 1 }\n return count\n}\n",
        "main proc() int {\n count := 0\n for (0..4) |_| count = count + 1\n return count\n}\n",
        "main proc() int {\n count := 0\n for 9223372036854775807..=9223372036854775807 |i| {\n count = count + 1\n if (count > 2) break\n continue\n }\n return count\n}\n",
        "main proc() int {\n count := 0\n for 9223372036854775806..=9223372036854775807 |_| {\n count = count + 1\n if (count > 3) break\n continue\n }\n return count\n}\n",
        "main proc() int {\n count := 0\n for 9223372036854775806..9223372036854775807 |i| {\n count = count + 1\n if (count > 2) break\n continue\n }\n return count\n}\n",
        "main proc() int {\n for (-9223372036854775808)..(-9223372036854775807) |i| { return i }\n return 0\n}\n",
        "main proc() int {\n sum := 0\n for 0..(3 + 1) |i| { sum = sum + i }\n return sum\n}\n",
    ]
    expected [13]i64 :: [21, 21, -3, 0, 0, 7, 0, 4, 1, 2, 1, minval!(i64), 6]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.int, outcome.value.type)
        try testing.expect_equal(expected[index], outcome.value.data.integer)
    }
}

range_bounds_calls_and_globals_are_frozen_before_branchful_body_calls test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `seed :: choose(true or false, identity(0))
        `limit :: choose(false or true, identity(4))
        `identity proc(value int) int { return value }
        `choose proc(flag bool, value int) int {
        `    if flag { return value }
        `    return 99
        `}
        `main proc() int {
        `    first := seed
        `    last := limit
        `    sum := 0
        `    for choose(true and !false, identity(first))..choose(false or true, choose(true or false, last)) |i| {
        `        sum = choose(i == 0 or i > 0, identity(sum + i))
        `        first = 100
        `        last = 0
        `    }
        `    return sum + 36
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)
}

range_break_continue_and_nested_for_while_restore_lexical_targets test {
    sources [3][]u8 :: [
        "main proc() int {\n sum := 0\n count := 0\n for 0..10 |i| {\n count = count + 1\n if (count > 12) break\n if (i == 2 or i == 4) continue\n if (i == 6) break\n sum = sum + i\n }\n return sum + 33\n}\n",
        "main proc() int {\n sum := 0\n count := 0\n for 0..3 |outer| {\n count = count + 1\n if (count > 4) break\n inner := 3\n while inner > 0 {\n inner = inner - 1\n if (inner == 1) continue\n if (inner == 0) break\n sum = sum + 7\n }\n if (outer < 2) continue else break\n }\n return sum + 21\n}\n",
        "main proc() int {\n outer := 3\n sum := 0\n while outer > 0 {\n outer = outer - 1\n count := 0\n for 0..3 |i| {\n count = count + 1\n if (count > 4) break\n for 0..3 |j| {\n if (j == 0) continue\n sum = sum + 7\n break\n }\n if (i == 0) continue else break\n }\n if (outer > 0) continue else break\n }\n return sum\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
    }
}

range_body_and_arm_locals_reset_before_continued_later_declarations test {
    sources [6][]u8 :: [
        "main proc() int {\n for 0..3 |i| {\n if i == 2 { return later }\n if (i == 1) continue\n later :: 42\n continue\n }\n return 0\n}\n",
        "main proc() int {\n for 0..3 |i| {\n if i == 2 { later = 42 }\n if (i == 1) continue\n later := 0\n continue\n }\n return 0\n}\n",
        "main proc() int {\n for 0..3 |i| {\n if true {\n if i == 2 { return later }\n if (i == 1) continue\n later :: 42\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n for 0..3 |i| {\n if true {\n if i == 2 { later = 42 }\n if (i == 1) continue\n later := 0\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n for 0..3 |i| {\n if false {} else {\n if i == 2 { return later }\n if (i == 1) continue\n later :: 42\n continue\n }\n }\n return 0\n}\n",
        "main proc() int {\n for 0..3 |i| {\n if false {} else {\n if i == 2 { later = 42 }\n if (i == 1) continue\n later := 0\n continue\n }\n }\n return 0\n}\n",
    ]
    codes [6]diagnostics.Code :: [
        .read_before_initialization, .write_before_initialization,
        .read_before_initialization, .write_before_initialization,
        .read_before_initialization, .write_before_initialization,
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
        diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
        try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], "later"))
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

untaken_range_errors_and_errors_after_controls_remain_diagnostic_only test {
    sources [10][]u8 :: [
        "main proc() int {\n for 0..0 |i| { return unknown }\n return 42\n}\n",
        "main proc() int {\n for 3..2 |i| { i = 1 }\n return 42\n}\n",
        "main proc() int {\n i :: 0\n for 0..0 |i| {}\n return 42\n}\n",
        "main proc() int {\n for 0..3 |i| {\n continue\n missing\n }\n return 42\n}\n",
        "main proc() int {\n for 0..3 |i| {\n break\n missing\n }\n return 42\n}\n",
        "main proc() int {\n for 0..3 |i| {\n return 42\n break\n continue\n missing\n }\n return 0\n}\n",
        "unused proc() int {\n for 0..1 |i| { return unknown }\n return 0\n}\nmain proc() int { return 42 }\n",
        "main proc() int {\n if false { for true..1 |i| {} }\n return 42\n}\n",
        "main proc() int {\n for 0..0 |int| {}\n return 42\n}\n",
        "unsupported :: 0..1\nmain proc() int {\n for 0..0 |_| { local :: 0..1 }\n return 42\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        count :: diagnostics.count(&diagnostic_store)
        try testing.expect(count > 0)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
        try testing.expect_equal(count, diagnostics.count(&diagnostic_store))
    }
}

demanded_range_header_capture_and_body_errors_keep_original_diagnostic_identity test {
    sources [10][]u8 :: [
        "main proc() int {\n for true..1 |i| {}\n return 42\n}\n",
        "main proc() int {\n for 0..1 |i| { i = 1 }\n return 42\n}\n",
        "main proc() int {\n i :: 0\n for 0..1 |i| {}\n return 42\n}\n",
        "main proc() int {\n for 0..1 |i| {\n missing\n continue\n }\n return 42\n}\n",
        "main proc() int {\n for 0..1 |i| {\n missing\n break\n }\n return 42\n}\n",
        "main proc() int {\n for 1 |i| {}\n return 42\n}\n",
        "main proc() int {\n 0..1\n return 42\n}\n",
        "main proc() int {\n for 0..1 |@i| {}\n return 42\n}\n",
        "main proc() int {\n for 0..1 |i, _| {}\n return 42\n}\n",
        "main proc() int {\n local :: 0..1\n return 42\n}\n",
    ]
    codes [10]diagnostics.Code :: [
        .invalid_range_bound, .invalid_assignment_target, .duplicate_name,
        .unknown_name, .unknown_name, .invalid_for_iterable, .range_value_not_supported,
        .range_pointer_capture, .range_index_capture, .range_value_not_supported,
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
        original :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(0))?
        try testing.expect_equal(codes[index], original.code)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        try testing.expect_equal(1, diagnostics.count(&diagnostic_store))
    }
}

range_bounds_evaluate_left_to_right_before_header_errors_and_body_overflow_keeps_span test {
    sources [4][]u8 :: [
        "first :: fail()\nsecond :: absent\nfail proc() int { return 9223372036854775807 + 1 }\nmain proc() int {\n for first..second |i| {}\n return 42\n}\n",
        "fail proc() int { return 9223372036854775807 + 1 }\nmain proc() int {\n for fail()..1 |@i| {}\n return 42\n}\n",
        "main proc() int {\n for 0..1 |i| { return 9223372036854775807 + i + 1 }\n return 0\n}\n",
        "main proc() int {\n for first_absent..second_absent |i| {}\n return 42\n}\n",
    ]
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        before :: diagnostics.count(&diagnostic_store)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        code diagnostics.Code :: if (index == 3) .unknown_name else .integer_overflow
        try expect_trap(outcome, &diagnostic_store, code)
        diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
        span []u8 :: match index {
            0, 1: "9223372036854775807 + 1"
            2: "9223372036854775807 + i + 1"
            3: "first_absent"
            else: unreachable
        }
        try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], span))
        if (index == 3) try testing.expect_equal(diagnostics.DiagnosticId(0), outcome.trap?)
        else try testing.expect_equal(diagnostics.DiagnosticId(before), outcome.trap?)
    }
}

range_runtime_allocations_do_not_grow_with_iterations test {
    sources [2][]u8 :: [
        "main proc() int {\n count := 0\n for 0..1 |i| {\n local :: i\n count = count + 1\n if (count > 1) break\n if (local >= 0) continue\n later :: 0\n }\n return count\n}\n",
        "main proc() int {\n count := 0\n for 0..10000 |i| {\n local :: i\n count = count + 1\n if (count > 10000) break\n if (local >= 0) continue\n later :: 0\n }\n return count\n}\n",
    ]
    expected [2]i64 :: [1, 10000]
    allocations := usize(0)
    for (sources) |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        state := AllocationState{ remaining = 64 }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := try interpreter.run(allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected[index], outcome.value.data.integer)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        if (index == 0) allocations = usize(64) - state.remaining
        else try testing.expect_equal(allocations, usize(64) - state.remaining)
    }
}

array_mutation_copies_rows_wholes_and_by_value_calls test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `seed :: later
        `later [2]mut [2]mut i64 :: [[1, 2], [3, 4]]
        `identity proc(value [2]mut [2]mut i64) [2]mut [2]mut i64 { return value }
        `changed proc(value [2]mut [2]mut i64) [2]mut [2]mut i64 {
        `    copy := value
        `    (copy[0])[0] = 20
        `    return copy
        `}
        `main proc() bool {
        `    a := identity(identity(seed))
        `    row := a[0]
        `    row[0] = 9
        `    b := changed(identity(a))
        `    (b[1])[1] = 30
        `    c := a
        `    c = b
        `    (b[0])[1] = 40
        `    a[1] = row
        `    row[1] = 50
        `    count usize :: 2
        `    sum := 0
        `    for 0..count |i| {
        `        for 0..count |j| { sum = sum + a[i][j] }
        `    }
        `    return sum == 14 and seed[0][0] == 1 and seed[1][1] == 4 and c[0][0] == 20 and c[0][1] == 2 and c[1][1] == 30
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect(outcome.value.data.boolean)
}

array_context_inference_empty_shapes_and_scalar_leaf_families test {
    sources [8][]u8 :: [
        "main proc() bool {\n a [_]mut i64 := [1, 2, 3]\n a[1] = 9\n return a[1] == 9\n}\n",
        "main proc() bool {\n a [0]bool :: []\n b :: []\n return true\n}\n",
        "main proc() bool {\n a [2]mut f64 := [1, 2.5]\n a[0] = 3.5\n return a[0] + a[1] == 6.0\n}\n",
        "main proc() bool {\n a [2]mut bool := [false or true, true and false]\n a[1] = true\n return a[0] and a[1]\n}\n",
        "main proc() string {\n a [2]mut string := [\"one\", \"two\"]\n b := a\n a[1] = \"three\"\n return b[1]\n}\n",
        "plus proc(n int) int { return n + 1 }\nminus proc(n int) int { return n - 1 }\nmain proc() bool {\n a :: [plus, minus]\n return a[0](41) == 42 and a[1](43) == 42\n}\n",
        "make proc() [2]i64 { return [20, 22] }\nmain proc() bool {\n return make()[0] + ([20, 22])[1] == 42\n}\n",
        "count :: forwarded + 1\nforwarded :: 1\nmain proc() bool {\n a [count][0]bool :: [[], []]\n return true\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        if (outcome.value.type == .string) try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.string), "two"))
        else try testing.expect(outcome.value.data.boolean)
    }
}

array_literal_scratch_handles_nested_calls_and_branchful_elements test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `identity proc(value [2]bool) [2]bool { return value }
        `pair proc(left [2]bool, right [2]bool) [2][2]bool { return [left, right] }
        `main proc() bool {
        `    value :: pair(identity([true or false, false and true]), identity(identity([false or true, true and !false])))
        `    return value[0][0] and !value[0][1] and value[1][0] and value[1][1]
        `}
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect(outcome.value.data.boolean)
}

array_bounds_roots_and_mutability_trap_at_demanded_positions test {
    sources [12][]u8 :: [
        "main proc() int {\n a :: [1]\n return a[1]\n}\n",
        "main proc() int {\n a [0]i64 :: []\n return a[0]\n}\n",
        "main proc() int {\n a [1]mut i64 := [1]\n a[18446744073709551615] = 2\n return 0\n}\n",
        "main proc() int {\n a [1]mut i64 :: [1]\n a[0] = 2\n return 0\n}\n",
        "main proc() int {\n a := [1]\n a[0] = 2\n return 0\n}\n",
        "a [1]mut i64 :: [1]\nmain proc() int {\n a[0] = 2\n return 0\n}\n",
        "bad proc(a [1]mut i64) int {\n a[0] = 2\n return 0\n}\nmain proc() int {\n return bad([1])\n}\n",
        "main proc() int {\n a [1]mut [1]i64 := [[1]]\n (a[0])[0] = 2\n return 0\n}\n",
        "main proc() int {\n a [1][1]mut i64 := [[1]]\n (a[0])[0] = 2\n return 0\n}\n",
        "a [1]i64 :: b\nb [1]i64 :: a\nmain proc() int {\n return a[0]\n}\n",
        "main proc() int {\n before :: after[0]\n after [1]i64 :: [1]\n return before\n}\n",
        "main proc() int {\n [1]i64\n return 0\n}\n",
    ]
    codes [12]diagnostics.Code :: [
        .index_out_of_bounds, .index_out_of_bounds, .index_out_of_bounds,
        .invalid_index_assignment, .invalid_index_assignment, .invalid_index_assignment,
        .invalid_index_assignment, .invalid_index_assignment, .invalid_index_assignment,
        .initialization_cycle, .read_before_initialization, .type_not_value,
    ]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[i])
    }
}

array_assignment_rhs_and_nested_bounds_preserve_error_order_and_identity test {
    sources [5][]u8 :: [
        "rhs proc() i64 { return absent_rhs }\nmain proc() int {\n a [0]mut i64 := []\n a[absent_index] = rhs()\n return 0\n}\n",
        "index proc() usize { return absent_inner }\nmain proc() int {\n a [1][1]i64 :: [[1]]\n return a[2][index()]\n}\n",
        "rhs proc() i64 { return absent_rhs }\nmain proc() int {\n a :: [1]\n a[0] = rhs()\n return 0\n}\n",
        "main proc() int {\n a [0]mut i64 := []\n a[0] = 9223372036854775807 + 1\n return 0\n}\n",
        "main proc() int {\n a [1]mut i64 := [1]\n a[absent_index] = absent_rhs\n return 0\n}\n",
    ]
    codes [5]diagnostics.Code :: [.unknown_name, .index_out_of_bounds, .unknown_name, .integer_overflow, .unknown_name]
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        before :: diagnostics.count(&diagnostic_store)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[i])
        if (i == 0 or i == 2 or i == 4) {
            diagnostic :: diagnostics.get(&diagnostic_store, outcome.trap?)?
            try testing.expect(mem.eql(source[usize(diagnostic.span.start)..usize(diagnostic.span.end)], "absent_rhs"))
            try testing.expect_equal(before, diagnostics.count(&diagnostic_store))
        }
    }
}

usize_arithmetic_and_guarded_ranges_use_unsigned_full_width test {
    sources [5][]u8 :: [
        "main proc() bool {\n max usize :: 18446744073709551615\n n := 0\n for max..=max |i| {\n if (i != max) return false\n n = n + 1\n continue\n }\n return n == 1\n}\n",
        "main proc() bool {\n max usize :: 18446744073709551615\n zero usize :: 0\n n := 0\n for max..max |_| { n = n + 1 }\n for zero..=zero |_| { n = n + 1 }\n return n == 1\n}\n",
        "main proc() bool {\n start usize :: 18446744073709551614\n end usize :: 18446744073709551615\n n := 0\n for start..=end |i| {\n n = n + 1\n continue\n }\n return n == 2\n}\n",
        "main proc() bool {\n a usize :: 9223372036854775808\n return a > 9223372036854775807 and a * 1 + 1 - 1 == a\n}\n",
        "main proc() bool {\n end usize :: 3\n sum usize := 0\n for 0..end |i| { sum = sum + i }\n return sum == 3\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect(outcome.value.data.boolean)
    }
}

aggregate_loop_frames_allocate_once_and_reset_local_freshness test {
    sources [2][]u8 :: [
        "main proc() int {\n end usize :: 1\n count := 0\n a [1]mut i64 := [0]\n for 0..end |i| {\n row [1]mut i64 := [a[0]]\n row[0] = row[0] + 1\n a = row\n count = count + 1\n }\n return count + a[0]\n}\n",
        "main proc() int {\n end usize :: 10000\n count := 0\n a [1]mut i64 := [0]\n for 0..end |i| {\n row [1]mut i64 := [a[0]]\n row[0] = row[0] + 1\n a = row\n count = count + 1\n }\n return count + a[0]\n}\n",
    ]
    expected [2]i64 :: [2, 20000]
    allocations := usize(0)
    for (sources) |source, i| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        state := AllocationState{ remaining = 64 }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := try interpreter.run(allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(expected[i], outcome.value.data.integer)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        if (i == 0) allocations = usize(64) - state.remaining
        else try testing.expect_equal(allocations, usize(64) - state.remaining)
    }
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned(
        "main proc() int {\n end usize :: 2\n for 0..end |i| {\n if (i == 1) return later[0]\n later [1]i64 :: [42]\n }\n return 0\n}\n",
        &diagnostic_store,
    )
    defer ir.deinit(&module)
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try expect_trap(outcome, &diagnostic_store, .read_before_initialization)
}

escaped_nested_array_returns_survive_frontend_and_frames_and_release_on_oom test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `later [2][2]string :: [["owned\none", "two"], ["three", "four"]]
        `first :: identity(later)
        `identity proc(value [2][2]string) [2][2]string { return value }
        `main proc() [2][2]string { return identity(identity(first)) }
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    succeeded := false
    failures := usize(0)
    for (usize(0)..usize(512)) |limit| {
        state := AllocationState{ remaining = limit }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := interpreter.run(allocator, &module, &diagnostic_store) catch |error| {
            try testing.expect(error == .out_of_memory)
            failures += 1
            try testing.expect_equal(usize(0), state.live)
            continue
        }
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.array, outcome.value.type)
        try testing.expect_equal(usize(4), outcome.value.data.elements.len)
        try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.elements[0].data.string), "owned\none"))
        try testing.expect(mem.eql(ir.string_bytes(&module, outcome.value.data.elements[3].data.string), "four"))
        try testing.expect(state.live > 0)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        succeeded = true
        break
    }
    try testing.expect(succeeded)
    try testing.expect(failures > 0)
}

unsigned_arithmetic_reports_overflow_without_signed_narrowing test {
    sources [3][]u8 :: [
        "main proc() usize {\n return 18446744073709551615 + 1\n}\n",
        "main proc() usize {\n return 0 - 1\n}\n",
        "main proc() usize {\n return 9223372036854775808 * 2\n}\n",
    ]
    for (sources) |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .integer_overflow)
    }
}

array_index_write_checks_initialization_after_rhs test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned(
        "main proc() int {\n a[0] = 42\n a [1]mut i64 := [0]\n return 0\n}\n",
        &diagnostic_store,
    )
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try expect_trap(outcome, &diagnostic_store, .write_before_initialization)
}

empty_array_entry_results_need_no_escaped_allocation test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned("main proc() [0]bool { return [] }\n", &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    state := AllocationState{ remaining = 64 }
    allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
    outcome := try interpreter.run(allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.array, outcome.value.type)
    try testing.expect_equal(usize(0), outcome.value.data.elements.len)
    try testing.expect_equal(usize(0), state.live)
    interpreter.deinit(&outcome)
    try testing.expect_equal(usize(0), state.live)
}

fallible_source_handlers_do_not_catch_runtime_allocation_failures test {
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `Error :: enum { out_of_memory }
        `fail proc() int ! Error { return .out_of_memory }
        `main proc() int { return fail() catch 42 }
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(usize(0), diagnostics.count(&diagnostic_store))
    succeeded := false
    failures := usize(0)
    for (usize(0)..usize(128)) |limit| {
        state := AllocationState{ remaining = limit }
        allocator :: mem.Allocator{ context = &state, vtable = &limited_vtable }
        outcome := interpreter.run(allocator, &module, &diagnostic_store) catch |error| {
            try testing.expect(error == .out_of_memory)
            failures += 1
            try testing.expect_equal(usize(0), state.live)
            try testing.expect_equal(usize(0), diagnostics.count(&diagnostic_store))
            continue
        }
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(i64(42), outcome.value.data.integer)
        interpreter.deinit(&outcome)
        try testing.expect_equal(usize(0), state.live)
        succeeded = true
        break
    }
    try testing.expect(succeeded and failures > 0)
}

keeps_generated_foreign_declarations_demand_driven_and_traps_interpreted_calls test {
    source ::
        `Handle :: opaque
        `Packet :: c_struct { context ?*mut Handle, callback ?*c_func(_ c_int, _ c_int) void }
        `unsupported c_func(_ Packet) Packet
        `variadic c_func(_ c_int, ...) c_int
        `single c_func(_ c_float) c_float
        `extended c_func(_ c_longdouble) c_longdouble
        `double c_func(_ c_double) c_double
        `malloc c_func(_ c_ulong) ?*mut anyopaque
        `@hide:file
        `helper proc() int { if (true) return 42
        `else return 0 }
        `main proc() int { return helper() }
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile_owned(source, &diagnostic_store)
    defer ir.deinit(&module)
    try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
    outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
    defer interpreter.deinit(&outcome)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(i64(42), outcome.value.data.integer)

    foreign_module := try compile_owned(
        "realloc c_func(_ ?*mut anyopaque, _ c_ulong) ?*mut anyopaque\nmain proc() bool { return realloc(null, 8) == null }\n",
        &diagnostic_store,
    )
    defer ir.deinit(&foreign_module)
    foreign_outcome := try interpreter.run(mem.c_allocator, &foreign_module, &diagnostic_store)
    defer interpreter.deinit(&foreign_outcome)
    try expect_trap(foreign_outcome, &diagnostic_store, .unsupported_foreign_call)
}

diagnoses_demanded_opaque_values_and_incompatible_opaque_pointers test {
    sources [2][]u8 :: [
        "Handle :: opaque\ntake c_func(_ Handle) void\nmain proc() void { take(undefined) }\n",
        "A :: opaque\nB :: opaque\nmain proc() void { a ?*A :: null\n b ?*B :: a }\n",
    ]
    for sources |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try testing.expect(outcome.trap != null)
    }
}

rejects_demanded_unavailable_c_floating_types_without_unknown_names test {
    sources [2][]u8 :: [
        "single c_func() c_float\nmain proc() void { single() }\n",
        "extended c_func() c_longdouble\nmain proc() void { extended() }\n",
    ]
    for sources |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .invalid_operand)
        for 0..diagnostics.count(&diagnostic_store) |index| {
            diagnostic :: diagnostics.get(&diagnostic_store, diagnostics.DiagnosticId(index))?
            try testing.expect(diagnostic.code != .unknown_name)
        }
    }
}

preserves_variadic_call_signatures_and_interpreter_foreign_traps test {
    sources [2][]u8 :: [
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { return take(1) }\n",
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { return take(1, true, i8(-2), u8(3), i16(-4), u16(5), 6.5) }\n",
    ]
    for sources |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        try testing.expect(module.functions.items[0].variadic)
        try testing.expect_equal(usize(1), module.functions.items[0].parameters.items.len)
        entry :: &module.functions.items[usize(module.entry?)]
        found := false
        for entry.blocks.items |block| {
            for block.instructions.items |instruction| {
                if (instruction.op != .call) continue
                found = true
                try testing.expect(instruction.variadic)
                try testing.expect_equal(usize(1), instruction.fixed_arguments)
            }
        }
        try testing.expect(found)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .unsupported_foreign_call)
    }
}

rejects_variadic_arity_fixed_types_and_non_c_trailing_values test {
    sources [4][]u8 :: [
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { return take() }\n",
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { return take(true) }\n",
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { return take(1, \"text\") }\n",
        "take c_func(_ c_int, ...) c_int\nmain proc() c_int { values [2]i64 :: [1, 2]\nreturn take(1, values) }\n",
    ]
    codes [4]diagnostics.Code :: [
        .argument_count_mismatch, .type_mismatch, .invalid_operand, .invalid_operand,
    ]
    for sources |source, index| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, codes[index])
    }
}

coerces_strings_to_immutable_byte_pointer_arguments test {
    sources [3][]u8 :: [
        "take c_func(_ ?*c_char) void\nmain proc() void { take(\"format\") }\n",
        "take c_func(_ *u8) void\nmain proc() void { take(\"format\") }\n",
        "take c_func(_ *i8, ...) void\nmain proc() void { take(\"format\", true) }\n",
    ]
    for sources |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        try testing.expect_equal(0, diagnostics.count(&diagnostic_store))
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .unsupported_foreign_call)
    }
}

rejects_string_arguments_for_mutable_or_nonbyte_pointers test {
    sources [2][]u8 :: [
        "take c_func(_ ?*mut c_char) void\nmain proc() void { take(\"format\") }\n",
        "take c_func(_ *u16) void\nmain proc() void { take(\"format\") }\n",
    ]
    for sources |source| {
        diagnostic_store := diagnostics.init(mem.c_allocator)
        defer diagnostics.deinit(&diagnostic_store)
        module := try compile_owned(source, &diagnostic_store)
        defer ir.deinit(&module)
        outcome := try interpreter.run(mem.c_allocator, &module, &diagnostic_store)
        defer interpreter.deinit(&outcome)
        try expect_trap(outcome, &diagnostic_store, .type_mismatch)
    }
}