[Clang] Fix handling of placeholder variables name in init captures (#107055)

We were incorrectly not deduplicating results when looking up `_` which,
for a lambda init capture, would result in an ambiguous lookup.

The same bug caused some diagnostic notes to be emitted twice.

Fixes #107024

2 files changed, 1 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index a8461a7..15ed857 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -1323,7 +1323,6 @@ void Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
 
     if (C->Init.isUsable()) {
       addInitCapture(LSI, cast<VarDecl>(Var), C->Kind == LCK_ByRef);
-      PushOnScopeChains(Var, CurScope, false);
     } else {
       TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef
                                                  : TryCapture_ExplicitByVal;
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 7a6a645..d3d4bf27 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -570,7 +570,7 @@ void LookupResult::resolveKind() {
 
     // For non-type declarations, check for a prior lookup result naming this
     // canonical declaration.
-    if (!D->isPlaceholderVar(getSema().getLangOpts()) && !ExistingI) {
+    if (!ExistingI) {
       auto UniqueResult = Unique.insert(std::make_pair(D, I));
       if (!UniqueResult.second) {
         // We've seen this entity before.