[clang] [clang] Fix null dereference on return in lambda attribute statement expr (PR #66643)

[Piotr Fusik via cfe-commits]

https://github.com/pfusik updated https://github.com/llvm/llvm-project/pull/66643

>From 4545c9c691a7affcab6cfe4e1b9b2a7715ab3f8b Mon Sep 17 00:00:00 2001
From: Piotr Fusik <piotr at fusion-lang.org>
Date: Mon, 18 Sep 2023 19:56:10 +0200
Subject: [PATCH] [clang] Fix null dereference on return in lambda attribute
 statement expr

clang was crashing on a lambda attribute with a statement expression
that contained a `return`.
It attempted to access the lambda type which was unknown at that point.

Fixes https://github.com/llvm/llvm-project/issues/48527
---
 clang/docs/ReleaseNotes.rst               |  4 ++++
 clang/lib/Sema/SemaStmt.cpp               |  2 ++
 clang/test/Parser/gh48527.cpp             | 10 ++++++++++
 clang/test/SemaCXX/lambda-expressions.cpp |  4 ++++
 4 files changed, 20 insertions(+)
 create mode 100644 clang/test/Parser/gh48527.cpp

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9b1578762e301f6..172818114c3b92b 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -301,6 +301,10 @@ Bug Fixes to C++ Support
   makes an invalid call to an immediate function.
   (`#66324 <https://github.com/llvm/llvm-project/issues/66324>`_)
 
+- Fix crash for a lambda attribute with a statement expression
+  that contains a `return`.
+  (`#48527 <https://github.com/llvm/llvm-project/issues/48527>`_)
+
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed an import failure of recursive friend class template.
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/Parser/gh48527.cpp b/clang/test/Parser/gh48527.cpp
new file mode 100644
index 000000000000000..420c35be37f5191
--- /dev/null
+++ b/clang/test/Parser/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 at +2 {{expected ')'}}
+// expected-error at +1 {{expected body of lambda expression}}
+// expected-error {{expected '}'}}
diff --git a/clang/test/SemaCXX/lambda-expressions.cpp b/clang/test/SemaCXX/lambda-expressions.cpp
index 23745dc14154747..0c9e8584e653473 100644
--- a/clang/test/SemaCXX/lambda-expressions.cpp
+++ b/clang/test/SemaCXX/lambda-expressions.cpp
@@ -714,3 +714,7 @@ void foo() {
   // CHECK-NEXT: ConstantExpr
   // CHECK-NEXT: value: Int 2
 }
+
+void GH48527() {
+  auto a = []()__attribute__((b(({ return 0; })))){}; // expected-warning {{unknown attribute 'b' ignored}}
+}