PR45000: Let Sema::SubstParmVarDecl handle default args of lambdas in initializers

Summary:
We extend the behavior for local functions and methods of local classes
to lambdas in variable initializers. The initializer is not a separate
scope, but we treat it as such.

We also remove the (faulty) instantiation of default arguments in
TreeTransform::TransformLambdaExpr, because it doesn't do proper
initialization, and if it did, we would do it twice (and thus also emit
eventual errors twice).

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D76038

(cherry picked from commit f43859a099fa3587123717be941fa63ba8d0d4f2)

3 files changed, 2 insertions, 15 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index b5d2ab1f31f..c53c37ee109 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2343,7 +2343,7 @@ ParmVarDecl *Sema::SubstParmVarDecl(ParmVarDecl *OldParm,
     UnparsedDefaultArgInstantiations[OldParm].push_back(NewParm);
   } else if (Expr *Arg = OldParm->getDefaultArg()) {
     FunctionDecl *OwningFunc = cast<FunctionDecl>(OldParm->getDeclContext());
-    if (OwningFunc->isLexicallyWithinFunctionOrMethod()) {
+    if (OwningFunc->isInLocalScope()) {
       // Instantiate default arguments for methods of local classes (DR1484)
       // and non-defining declarations.
       Sema::ContextRAII SavedContext(*this, OwningFunc);
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 37dace3bee7..f801e79c890 100755
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4367,7 +4367,7 @@ TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
         EPI.ExceptionSpec.Type != EST_None &&
         EPI.ExceptionSpec.Type != EST_DynamicNone &&
         EPI.ExceptionSpec.Type != EST_BasicNoexcept &&
-        !Tmpl->isLexicallyWithinFunctionOrMethod()) {
+        !Tmpl->isInLocalScope()) {
       FunctionDecl *ExceptionSpecTemplate = Tmpl;
       if (EPI.ExceptionSpec.Type == EST_Uninstantiated)
         ExceptionSpecTemplate = EPI.ExceptionSpec.SourceTemplate;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 30fb089742e..bbc6fc6deee 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -11828,19 +11828,6 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
 
   LSI->CallOperator = NewCallOperator;
 
-  for (unsigned I = 0, NumParams = NewCallOperator->getNumParams();
-       I != NumParams; ++I) {
-    auto *P = NewCallOperator->getParamDecl(I);
-    if (P->hasUninstantiatedDefaultArg()) {
-      EnterExpressionEvaluationContext Eval(
-          getSema(),
-          Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed, P);
-      ExprResult R = getDerived().TransformExpr(
-          E->getCallOperator()->getParamDecl(I)->getDefaultArg());
-      P->setDefaultArg(R.get());
-    }
-  }
-
   getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
   getDerived().transformedLocalDecl(E->getCallOperator(), {NewCallOperator});