report global cycle endpoints

compiler_tests.odin

@@ -4684,6 +4684,33 @@ hundred_thousand_term_runtime_addition_uses_iterative_pipeline :: proc(t: ^testi
 	testing.expect(t, instruction_count > 100_000)
 }
 
+@(test)
+global_cycle_diagnostic_reports_endpoint_lines :: proc(t: ^testing.T) {
+	text := `a i32 :: b
+b i32 :: a
+main func() void {}
+`
+	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)
+
+	found := false
+	for _, diagnostic_index in diagnostics.items {
+		message := source.format(&diagnostics, source.diagnostic_id(diagnostic_index))
+		found = found || strings.contains(message, "global initialization cycle from 'a' at test.bro:1 to 'b' at test.bro:2")
+		delete(message)
+	}
+	testing.expect(t, found)
+}
+
 @(test)
 deep_global_cycle_detection_uses_iterative_dfs :: proc(t: ^testing.T) {
 	count := 50_000