[clang] c7daab2 - [Clang] Fix the trailing comma regression (#136273)

[via cfe-commits]

Author: Younan Zhang
Date: 2025-04-18T16:27:27+08:00
New Revision: c7daab259c3281cf8f649583993bad2536febc02

URL: https://github.com/llvm/llvm-project/commit/c7daab259c3281cf8f649583993bad2536febc02
DIFF: https://github.com/llvm/llvm-project/commit/c7daab259c3281cf8f649583993bad2536febc02.diff

LOG: [Clang] Fix the trailing comma regression (#136273)

925e195 introduced a regression since which we started to accept invalid
trailing commas in many expression lists where they're not allowed by
the grammar. The issue came from the fact that an additional invalid
state - previously handled by ParseExpressionList - was overlooked in
that patch.

Fixes https://github.com/llvm/llvm-project/issues/136254

No release entry because I want to backport it.

Added: 
    

Modified: 
    clang/lib/Parse/ParseExpr.cpp
    clang/test/Parser/recovery.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 1416d52157dca..3e3e7cbcd68b2 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -2239,8 +2239,6 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
             if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
               RunSignatureHelp();
             LHS = ExprError();
-          } else if (!HasError && HasTrailingComma) {
-            Diag(Tok, diag::err_expected_expression);
           } else if (LHS.isInvalid()) {
             for (auto &E : ArgExprs)
               Actions.CorrectDelayedTyposInExpr(E);
@@ -3750,7 +3748,6 @@ bool Parser::ParseExpressionList(SmallVectorImpl<Expr *> &Exprs,
     if (Tok.is(tok::r_paren)) {
       if (HasTrailingComma)
         *HasTrailingComma = true;
-      break;
     }
   }
   if (SawError) {

diff  --git a/clang/test/Parser/recovery.cpp b/clang/test/Parser/recovery.cpp
index 2fce67a52c6b6..261f5dc99bad4 100644
--- a/clang/test/Parser/recovery.cpp
+++ b/clang/test/Parser/recovery.cpp
@@ -222,3 +222,21 @@ void k() {
   func(1, ); // expected-error {{expected expression}}
 }
 }
+
+namespace GH136254 {
+
+void call() {
+  [a(42, )]() {} (); // expected-error {{expected expression}}
+
+  int *b = new int(42, ); // expected-error {{expected expression}}
+
+  struct S {
+    int c;
+
+    S() : c(42, ) {} // expected-error {{expected expression}}
+  };
+
+  int d(42, ); // expected-error {{expected expression}}
+}
+
+}