errdefer and try/defer fix

examples/programs/defer/main.bro

@@ -1,4 +1,4 @@
-# Milestone 19: `defer` and bare block statements.
+# Milestone 19: `defer`, `errdefer`, and bare block statements.
 #
 # `defer <stmt>` runs the statement when the enclosing scope exits, in reverse
 # (LIFO) order, on every exit path. A bare `{ ... }` introduces a scope. Each
@@ -24,6 +24,66 @@ enclosing_defer_check func() i32 {
 	return v # 0->1 (i=0 fall-through), ->2 (i=1 break); the +100 runs after capture
 }
 
+CleanupError :: enum {
+	bad
+}
+
+ExtraError :: enum {
+	extra
+}
+
+CleanupErrors :: alias CleanupError | ExtraError
+
+explicit_cleanup func(fail bool, trace *mut i32) i32 ! CleanupError {
+	defer trace^ = trace^ * 10 + 1
+	errdefer |err| {
+		if (err == .bad) {
+			trace^ = trace^ * 10 + 2
+		} else {
+			trace^ = 99
+		}
+	}
+	defer trace^ = trace^ * 10 + 3
+	if (fail) return .bad
+	return 7
+}
+
+fail_cleanup func() i32 ! CleanupError {
+	return .bad
+}
+
+try_cleanup func(trace *mut i32) i32 ! CleanupError {
+	defer trace^ = trace^ * 10 + 4
+	errdefer trace^ = trace^ * 10 + 5
+	return try fail_cleanup()
+}
+
+widen_cleanup func(trace *mut i32) i32 ! CleanupErrors {
+	errdefer |err| {
+		match err {
+			.bad: trace^ = trace^ * 10 + 6
+			.extra: trace^ = 99
+		}
+	}
+	return try fail_cleanup()
+}
+
+scoped_cleanup func(trace *mut i32) i32 ! CleanupError {
+	errdefer trace^ = trace^ * 10 + 7
+	{
+		errdefer trace^ = 99
+	}
+	return .bad
+}
+
+multi_exit_cleanup func(direct bool, trace *mut i32) i32 ! CleanupError {
+	errdefer |err| {
+		if (err == .bad) trace^ = trace^ + 8
+	}
+	if (direct) return .bad
+	return try fail_cleanup()
+}
+
 main func() i32 {
 	# 1. return value captured before defers run.
 	if (spill_check() != 5) return 101
@@ -78,5 +138,31 @@ main func() i32 {
 	# 7. break does not run an enclosing function-scope defer.
 	if (enclosing_defer_check() != 2) return 107
 
+	# 8. errdefer is skipped on success; ordinary defers stay interleaved.
+	trace i32 = 0
+	if ((explicit_cleanup(false, &trace) catch 0) != 7 or trace != 31) return 108
+
+	# 9. Explicit errors run errdefer and expose the captured error.
+	trace = 0
+	if ((explicit_cleanup(true, &trace) catch 9) != 9 or trace != 321) return 109
+
+	# 10. Propagated errors run both errdefer and ordinary defer.
+	trace = 0
+	if ((try_cleanup(&trace) catch 9) != 9 or trace != 54) return 110
+
+	# 11. Captures observe the widened enclosing error type.
+	trace = 0
+	if ((widen_cleanup(&trace) catch 9) != 9 or trace != 6) return 111
+
+	# 12. An errdefer expires when its block exits normally.
+	trace = 0
+	if ((scoped_cleanup(&trace) catch 9) != 9 or trace != 7) return 112
+
+	# 13. One captured errdefer can be replayed at several distinct error exits.
+	trace = 0
+	_ = multi_exit_cleanup(true, &trace) catch 0
+	_ = multi_exit_cleanup(false, &trace) catch 0
+	if (trace != 16) return 113
+
 	return 42
 }