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
    strpool.strings = strpool.init(mem.c_allocator)
    defer strpool.deinit(&strpool.strings)
    scan_state := lexer.init(mem.c_allocator)
    defer lexer.deinit(&scan_state)
    try lexer.scan(&scan_state, source, 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, 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)
    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)
    try testing.expect(outcome.trap == null)
    try testing.expect_equal(ir.Type.string, outcome.value.type)
    try testing.expect(mem.eql(outcome.value.data.string, "a\\\"\n\r\t\x00Az"))
}

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)
    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
        `alias :: add
        `later :: 18
        `add proc(left int, right int) int {
        `    local_alias :: alias
        `    return left + right
        `}
        `main proc() int {
        `    invoke :: alias
        `    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)
    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)
    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)
        try testing.expect(outcome.trap == null)
        try testing.expect_equal(ir.Type.void, outcome.value.type)
    }
}

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)
    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)
    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)
        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)
        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)
        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)
        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)
        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)
    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)
    try expect_trap(trapped, &diagnostic_store, .literal_out_of_range)
}

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)
        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 {
    strpool.strings = strpool.init(mem.c_allocator)
    defer strpool.deinit(&strpool.strings)
    diagnostic_store := diagnostics.init(mem.c_allocator)
    defer diagnostics.deinit(&diagnostic_store)
    source ::
        `text :: "owned\nstring"
        `factor float :: 3.5
        `identity proc(value string) string {
        `    if false {
        `        return value
        `    }
        `    local :: value
        `    return local
        `}
        `main proc() string {
        `    computed float :: factor * 2
        `    if computed > 0 {
        `        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, &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, &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(128)) |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
        }
        outcome :: interpreter.run(mem.c_allocator, &module, &diagnostic_store) catch |error| {
            ir.deinit(&module)
            return error
        }
        ir.deinit(&module)
        try testing.expect(outcome.trap == null)
        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)
    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)
    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)
        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)
        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)
        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)
    try expect_trap(outcome, &diagnostic_store, .read_before_initialization)
}