[torque] forbid brace-free if-else

Bug: v8:8012 v8:7793
Change-Id: Idc5d685d021fd107974b4415f7b855397004cb53
Reviewed-on: https://chromium-review.googlesource.com/1160841Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54893}

src/torque/torque-parser.cc

@@ -456,6 +456,13 @@ base::Optional<ParseResult> MakeIfStatement(
   auto condition = child_results->NextAs<Expression*>();
   auto if_true = child_results->NextAs<Statement*>();
   auto if_false = child_results->NextAs<base::Optional<Statement*>>();
+
+  if (if_false && !(BlockStatement::DynamicCast(if_true) &&
+                    (BlockStatement::DynamicCast(*if_false) ||
+                     IfStatement::DynamicCast(*if_false)))) {
+    ReportError("if-else statements require curly braces");
+  }
+
   Statement* result =
       MakeNode<IfStatement>(is_constexpr, condition, if_true, if_false);
   return ParseResult{result};

test/torque/test-torque.tq

@@ -98,10 +98,11 @@ module test {
   }
 
   macro LabelTestHelper4(flag: constexpr bool): never labels Label4, Label5 {
-    if
-      constexpr(flag) goto Label4;
-    else
+    if constexpr(flag) {
+      goto Label4;
+    } else {
       goto Label5;
+    }
   }
 
   macro CallLabelTestHelper4(flag: constexpr bool): bool {
@@ -120,10 +121,11 @@ module test {
     let r1: bool = CallLabelTestHelper4(true);
     let r2: bool = CallLabelTestHelper4(false);
 
-    if (r1 && !r2)
+    if (r1 && !r2) {
       return True;
-    else
+    } else {
       return False;
+    }
   }
 
   macro GenericMacroTest<T : type>(param: T): Object {