[clang] Fix null dereference on return in lambda attribute statement expr

[pfusik]

Fixes #48527

[llvmbot]

@llvm/pr-subscribers-clang

Changes

Fixes #48527

Full diff: https://github.com/llvm/llvm-project/pull/66643.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaStmt.cpp (+2)
• (added) clang/test/SemaCXX/gh48527.cpp (+10)

diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 7cc509542d5381d..10adfbc406dfbb5 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3577,6 +3577,8 @@ StmtResult Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,
   CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
   QualType FnRetType = CurCap->ReturnType;
   LambdaScopeInfo *CurLambda = dyn_cast<LambdaScopeInfo>(CurCap);
+  if (CurLambda && CurLambda->CallOperator->getType().isNull())
+    return StmtError();
   bool HasDeducedReturnType =
       CurLambda && hasDeducedReturnType(CurLambda->CallOperator);
 
diff --git a/clang/test/SemaCXX/gh48527.cpp b/clang/test/SemaCXX/gh48527.cpp
new file mode 100644
index 000000000000000..420c35be37f5191
--- /dev/null
+++ b/clang/test/SemaCXX/gh48527.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int main() { // expected-note {{to match this '{'}}
+    auto a = [](void)__attribute__((b(({ // expected-note {{to match this '('}}
+    return 0;
+} // expected-error 3 {{expected ')'}} \
+  // expected-error {{expected ';' at end of declaration}}
+// expected-error@+2 {{expected ')'}}
+// expected-error@+1 {{expected body of lambda expression}}
+// expected-error {{expected '}'}}

[Fznamznon]

The change needs a release note, otherwise looks good.
Right, @cor3ntin ?

[cor3ntin]

@Fznamznon I think so too, although I'd be inclined to move the test to clang/test/Parser/ because even though the fix is in Sema, it's testing a wrong parse.

The commit message also could do with a longer description.

Otherwise LGTM

[pfusik]

I'd be inclined to move the test to clang/test/Parser/ because even though the fix is in Sema, it's testing a wrong parse.

It's an ICE in Sema. The test is identical to the bug report, but it doesn't mean the issue is limited to syntax errors.

int main() {
    []()__attribute__((b(({ return 0; })))){};
}

g++ accepts the above while Clang crashes. I'll add this as a second test.

[cor3ntin]

I would still move the original test, things in sema usually at least parse (ie, this has unbalanced parens). I won't insist though

[pfusik]

@cor3ntin to test/CXX/what or test/Parser ?

[cor3ntin]

test/Parser. CXX is for tests that map very directly to a paragraph in the standard

[cor3ntin]

This can move to clang/test/SemaCXX/lambda-expressions.cpp
(the name of the function can have the number of the GH issue)

We try to limit the number of test files

[cor3ntin]

LGTM, thanks!

[pfusik]

Rebased resolving the conflict in release notes.

[shafik]

LGTM