[Clang] Fix evaluation of parameters of lambda call operator attributes

Fix a regresion introduced by D124351.
Attributes of lambda call operator were evaluated in the
context of the closure object type rather than its operator,
causing an assertion failure.

This was because we temporarily switch to the class lambda to
produce the mangling of the lambda, but we stayed in that
context too long.

Reviewed By: eandrews, aaron.ballman

Differential Revision: https://reviews.llvm.org/D146535

Author: cor3ntin

clang/lib/Sema/SemaLambda.cpp

@@ -390,6 +390,9 @@ buildTypeForLambdaCallOperator(Sema &S, clang::CXXRecordDecl *Class,
 void Sema::handleLambdaNumbering(
     CXXRecordDecl *Class, CXXMethodDecl *Method,
     std::optional<std::tuple<bool, unsigned, unsigned, Decl *>> Mangling) {
+
+  ContextRAII ManglingContext(*this, Class->getDeclContext());
+
   if (Mangling) {
     bool HasKnownInternalLinkage;
     unsigned ManglingNumber, DeviceManglingNumber;
@@ -1324,8 +1327,6 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
       ParamInfo.getDeclSpec().getConstexprSpecifier(),
       IsLambdaStatic ? SC_Static : SC_None, Params, ExplicitResultType);
 
-  ContextRAII ManglingContext(*this, Class->getDeclContext());
-
   CheckCXXDefaultArguments(Method);
 
   // This represents the function body for the lambda function, check if we
@@ -1350,8 +1351,6 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
 
   handleLambdaNumbering(Class, Method);
 
-  ManglingContext.pop();
-
   for (auto &&C : LSI->Captures) {
     if (!C.isVariableCapture())
       continue;

clang/test/SemaCXX/lambda-expressions.cpp

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -std=c++14 -Wno-unused-value -fsyntax-only -verify -verify=expected-cxx14 -fblocks %s
-// RUN: %clang_cc1 -std=c++17 -Wno-unused-value -fsyntax-only -verify -fblocks %s
+// RUN: %clang_cc1 -std=c++17 -Wno-unused-value -verify -ast-dump -fblocks %s | FileCheck %s
 
 namespace std { class type_info; };
 
@@ -704,3 +704,13 @@ static_assert([]() constexpr {
 }());
 } // namespace GH60936
 #endif
+
+// Call operator attributes refering to a variable should
+// be properly handled after D124351
+constexpr int i = 2;
+void foo() {
+  (void)[=][[gnu::aligned(i)]] () {}; // expected-warning{{C++2b extension}}
+  // CHECK: AlignedAttr
+  // CHECK-NEXT: ConstantExpr
+  // CHECK-NEXT: value: Int 2
+}