implicit address-taking for array slices

compiler_tests.odin

@@ -1017,6 +1017,78 @@ immutable_pointer_and_slice_bindings_preserve_mutable_pointees :: proc(t: ^testi
 	testing.expect_value(t, len(diagnostics.items), 0)
 }
 
+@(test)
+slicing_an_array_variable_takes_its_address_implicitly :: proc(t: ^testing.T) {
+	// Milestone 10: `arr[a..b]` on an array variable slices without an explicit
+	// `&`. The slice operand must be a pointer to the array (getelementptr off a
+	// `ptr`), not the array value.
+	text := `sink :: func(s []i32) i32 {
+	return s[0]
+}
+main :: func() i32 {
+	arr [4]i32 = [10, 20, 30, 40]
+	full :: sink(arr[..])
+	part :: sink(arr[1..3])
+	return full + part
+}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+	ir_module := lower.lower(&hir_module)
+	defer ir.destroy_module(&ir_module)
+	llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+	defer delete(llvm_text)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect(t, strings.contains(llvm_text, "getelementptr [4 x i32], ptr"))
+}
+
+@(test)
+slicing_an_array_rvalue_materializes_a_temporary :: proc(t: ^testing.T) {
+	// The checker accepts slicing a non-location array (here, a by-value array
+	// return). Lowering must store it into a temporary and slice that address;
+	// otherwise the slice operand is an array value, which is an invalid pointer.
+	text := `make_arr :: func() [4]i32 {
+	return [1, 2, 3, 4]
+}
+sink :: func(s []i32) i32 {
+	return s[0]
+}
+main :: func() i32 {
+	return sink(make_arr()[0..])
+}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+	ir_module := lower.lower(&hir_module)
+	defer ir.destroy_module(&ir_module)
+	llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+	defer delete(llvm_text)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	// The materialization store of the array rvalue into its temporary.
+	testing.expect(t, strings.contains(llvm_text, "store [4 x i32]"))
+	testing.expect(t, strings.contains(llvm_text, "getelementptr [4 x i32], ptr"))
+}
+
 @(test)
 c_variadic_calls_promote_extras_and_emit_variadic_llvm :: proc(t: ^testing.T) {
 text := `variadic :: c_func(tag c_int, ...) c_int