[clang]set invalid for lambda which missing capture this (#70432)

It can suppression further crash.
Fixes: #67687

Author: HerrCai0907

clang/docs/ReleaseNotes.rst

@@ -529,6 +529,8 @@ Bug Fixes in This Version
   ``thread_local`` instead of ``_Thread_local``.
   Fixes (`#70068 <https://github.com/llvm/llvm-project/issues/70068>`_) and
   (`#69167 <https://github.com/llvm/llvm-project/issues/69167>`_)
+- Fix crash in evaluating invalid lambda expression which forget capture this.
+  Fixes (`#67687 <https://github.com/llvm/llvm-project/issues/67687>`_)
 - Fix crash from constexpr evaluator evaluating uninitialized arrays as rvalue.
   Fixes (`#67317 <https://github.com/llvm/llvm-project/issues/67317>`_)
 

clang/lib/Sema/SemaExprCXX.cpp

@@ -1333,6 +1333,7 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
       if (LSI && isGenericLambdaCallOperatorSpecialization(LSI->CallOperator)) {
         // This context can't implicitly capture 'this'; fail out.
         if (BuildAndDiagnose) {
+          LSI->CallOperator->setInvalidDecl();
           Diag(Loc, diag::err_this_capture)
               << (Explicit && idx == MaxFunctionScopesIndex);
           if (!Explicit)
@@ -1354,10 +1355,11 @@ bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
         continue;
       }
       // This context can't implicitly capture 'this'; fail out.
-      if (BuildAndDiagnose)
+      if (BuildAndDiagnose) {
+        LSI->CallOperator->setInvalidDecl();
         Diag(Loc, diag::err_this_capture)
             << (Explicit && idx == MaxFunctionScopesIndex);
-
+      }
       if (!Explicit)
         buildLambdaThisCaptureFixit(*this, LSI);
       return true;

clang/test/SemaCXX/lambda-expressions.cpp

@@ -382,6 +382,14 @@ namespace PR18128 {
   };
 }
 
+namespace gh67687 {
+struct S {
+  int n;
+  int a = (4, []() { return n; }());  // expected-error {{'this' cannot be implicitly captured in this context}} \
+                                      // expected-note {{explicitly capture 'this'}}
+};
+}
+
 namespace PR18473 {
   template<typename T> void f() {
     T t(0);