[AST] Suppress the spammy "attempt to use a deleted fucntion" diagnostic.

Summary:
This patch fixes the regression diagnostic, which was introduced in
https://reviews.llvm.org/D77395.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: rsmith, adamcz, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78100

Author: hokein

clang/lib/Sema/SemaDecl.cpp

@@ -12554,12 +12554,17 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
     InitializationSequence InitSeq(*this, Entity, Kind, None);
     ExprResult Init = InitSeq.Perform(*this, Entity, Kind, None);
 
-    // If default-init fails, leave var uninitialized but valid, for recovery.
-
     if (Init.get()) {
       Var->setInit(MaybeCreateExprWithCleanups(Init.get()));
       // This is important for template substitution.
       Var->setInitStyle(VarDecl::CallInit);
+    } else if (Init.isInvalid()) {
+      // If default-init fails, attach a recovery-expr initializer to track
+      // that initialization was attempted and failed.
+      auto RecoveryExpr =
+          CreateRecoveryExpr(Var->getLocation(), Var->getLocation(), {});
+      if (RecoveryExpr.get())
+        Var->setInit(RecoveryExpr.get());
     }
 
     CheckCompleteVariableDeclaration(Var);

clang/lib/Sema/SemaDeclCXX.cpp

@@ -15002,6 +15002,10 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
 
 void Sema::FinalizeVarWithDestructor(VarDecl *VD, const RecordType *Record) {
   if (VD->isInvalidDecl()) return;
+  // If initializing the variable failed, don't also diagnose problems with
+  // the desctructor, they're likely related.
+  if (VD->getInit() && VD->getInit()->containsErrors())
+    return;
 
   CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(Record->getDecl());
   if (ClassDecl->isInvalidDecl()) return;

clang/test/SemaCXX/recovery-default-init.cpp

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -fsyntax-only -frecovery-ast -verify -std=c++11
+
+// NOTE: the test can be merged into existing tests once -frecovery-ast is on
+// by default.
+
+struct Foo { // expected-note {{candidate constructor (the implicit copy constructor) not viable}}
+  Foo(int); // expected-note {{candidate constructor not viable}}
+  ~Foo() = delete;
+};
+
+void test() {
+  // we expect the "attempt to use a deleted function" diagnostic is suppressed.
+  Foo foo; // expected-error {{no matching constructor for initialization of}}
+}