fix comptime yield targeting

compiler_tests.odin

@@ -5064,7 +5064,7 @@ main func() void {
 		found_expired = found_expired || strings.contains(message, "expired storage")
 		found_quota = found_quota || strings.contains(message, "comptime evaluation exceeded the step quota")
 		found_missing = found_missing || strings.contains(message, "did not return a value")
-		found_yield = found_yield || strings.contains(message, "comptime block must yield a value")
+		found_yield = found_yield || strings.contains(message, "a value block must end with an explicit 'yield'")
 	}
 	testing.expect(t, found_runtime)
 	testing.expect(t, runtime_only_count >= 2)
@@ -7428,6 +7428,64 @@ yield_misuse_is_diagnosed :: proc(t: ^testing.T) {
 	testing.expect(t, misplaced_yield)
 }
 
+@(test)
+comptime_yield_targets_match_value_source_semantics :: proc(t: ^testing.T) {
+	directory := "/tmp/brolang-test-comptime-yield-targets"
+	main_path := "/tmp/brolang-test-comptime-yield-targets/main.bro"
+	output := "/tmp/brolang-test-comptime-yield-targets-output"
+	valid_text := `selected :: ${
+	via_if :: if true {
+		yield 1
+	} else {
+		yield 2
+	}
+	via_label :: done: {
+		if true {
+			yield :done 3
+		}
+		yield :done 4
+	}
+	yield via_if + via_label
+}
+
+main func() i32 { return selected - 4 }
+`
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(output)
+	testing.expect(t, os.make_directory(directory) == nil)
+	testing.expect(t, os.write_entire_file(main_path, transmute([]byte)valid_text))
+	testing.expect_value(t, compiler_core.compile_package(directory, output), 0)
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 0)
+
+	invalid_text := `invalid :: ${
+	if false {
+		yield 1
+	}
+	yield 2
+}
+
+main func() void {}
+`
+	source_file := source.Source{path="invalid_comptime_yield.bro", text=invalid_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)
+	found := false
+	for diagnostic in diagnostics.items {
+		found = found || strings.contains(diagnostic.message, "'yield' is only valid as the final statement of a value block")
+	}
+	testing.expect(t, found)
+}
+
 @(test)
 yield_control_flow_is_diagnosed :: proc(t: ^testing.T) {
 	// Value if/loop/block misuse: an `if` value without an `else`; a branch that neither