[Sema] If CheckPlaceholderExpr rewrites the initializer of an auto

variable during auto type deduction, use the rewritten initializer when
performing initialization of the variable.

This silences spurious -Warc-repeated-use-of-weak warnings that are
issued when the initializer uses a weak ObjC pointer.

Differential Revision: https://reviews.llvm.org/D55662

llvm-svn: 350917

clang/include/clang/Sema/Sema.h

@@ -1960,7 +1960,7 @@ class Sema {
   bool CheckVariableDeclaration(VarDecl *NewVD, LookupResult &Previous);
   void CheckVariableDeclarationType(VarDecl *NewVD);
   bool DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
-                                     Expr *Init);
+                                     Expr *&Init);
   void CheckCompleteVariableDeclaration(VarDecl *VD);
   void CheckCompleteDecompositionDeclaration(DecompositionDecl *DD);
   void MaybeSuggestAddingStaticToDecl(const FunctionDecl *D);
@@ -7095,7 +7095,7 @@ class Sema {
   QualType deduceVarTypeFromInitializer(VarDecl *VDecl, DeclarationName Name,
                                         QualType Type, TypeSourceInfo *TSI,
                                         SourceRange Range, bool DirectInit,
-                                        Expr *Init);
+                                        Expr *&Init);
 
   TypeLoc getReturnTypeLoc(FunctionDecl *FD) const;
 

clang/lib/Sema/SemaDecl.cpp

@@ -10812,7 +10812,7 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
                                             DeclarationName Name, QualType Type,
                                             TypeSourceInfo *TSI,
                                             SourceRange Range, bool DirectInit,
-                                            Expr *Init) {
+                                            Expr *&Init) {
   bool IsInitCapture = !VDecl;
   assert((!VDecl || !VDecl->isInitCapture()) &&
          "init captures are expected to be deduced prior to initialization");
@@ -10928,7 +10928,8 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
           << (DeduceInit->getType().isNull() ? TSI->getType()
                                              : DeduceInit->getType())
           << DeduceInit->getSourceRange();
-  }
+  } else
+    Init = DeduceInit;
 
   // Warn if we deduced 'id'. 'auto' usually implies type-safety, but using
   // 'id' instead of a specific object type prevents most of our usual
@@ -10945,7 +10946,7 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
 }
 
 bool Sema::DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
-                                         Expr *Init) {
+                                         Expr *&Init) {
   QualType DeducedType = deduceVarTypeFromInitializer(
       VDecl, VDecl->getDeclName(), VDecl->getType(), VDecl->getTypeSourceInfo(),
       VDecl->getSourceRange(), DirectInit, Init);
@@ -11451,8 +11452,9 @@ void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
       return;
     }
 
+    Expr *TmpInit = nullptr;
     if (Type->isUndeducedType() &&
-        DeduceVariableDeclarationType(Var, false, nullptr))
+        DeduceVariableDeclarationType(Var, false, TmpInit))
       return;
 
     // C++11 [class.static.data]p3: A static data member can be declared with

clang/lib/Sema/SemaExprCXX.cpp

@@ -1865,12 +1865,11 @@ Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
     if (Braced && !getLangOpts().CPlusPlus17)
       Diag(Initializer->getBeginLoc(), diag::ext_auto_new_list_init)
           << AllocType << TypeRange;
-    Expr *Deduce = Inits[0];
     QualType DeducedType;
-    if (DeduceAutoType(AllocTypeInfo, Deduce, DeducedType) == DAR_Failed)
+    if (DeduceAutoType(AllocTypeInfo, Inits[0], DeducedType) == DAR_Failed)
       return ExprError(Diag(StartLoc, diag::err_auto_new_deduction_failure)
-                       << AllocType << Deduce->getType()
-                       << TypeRange << Deduce->getSourceRange());
+                       << AllocType << Inits[0]->getType()
+                       << TypeRange << Inits[0]->getSourceRange());
     if (DeducedType.isNull())
       return ExprError();
     AllocType = DeducedType;

clang/lib/Sema/SemaLambda.cpp

@@ -759,14 +759,15 @@ QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
   TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
 
   // Deduce the type of the init capture.
+  Expr *DeduceInit = Init;
   QualType DeducedType = deduceVarTypeFromInitializer(
       /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
-      SourceRange(Loc, Loc), IsDirectInit, Init);
+      SourceRange(Loc, Loc), IsDirectInit, DeduceInit);
   if (DeducedType.isNull())
     return QualType();
 
   // Are we a non-list direct initialization?
-  ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
+  bool CXXDirectInit = isa<ParenListExpr>(Init);
 
   // Perform initialization analysis and ensure any implicit conversions
   // (such as lvalue-to-rvalue) are enforced.
@@ -779,10 +780,7 @@ QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
                            : InitializationKind::CreateDirectList(Loc))
           : InitializationKind::CreateCopy(Loc, Init->getBeginLoc());
 
-  MultiExprArg Args = Init;
-  if (CXXDirectInit)
-    Args =
-        MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
+  MultiExprArg Args = DeduceInit;
   QualType DclT;
   InitializationSequence InitSeq(*this, Entity, Kind, Args);
   ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);

clang/test/SemaObjC/arc-repeated-weak.mm

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-arc -fblocks -Wno-objc-root-class -std=c++11 -Warc-repeated-use-of-weak -verify %s
-// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-weak -fblocks -Wno-objc-root-class -std=c++11 -Warc-repeated-use-of-weak -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-arc -fblocks -Wno-objc-root-class -std=c++14 -Warc-repeated-use-of-weak -verify %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-runtime-has-weak -fobjc-weak -fblocks -Wno-objc-root-class -std=c++14 -Warc-repeated-use-of-weak -verify %s
 
 @interface Test {
 @public
@@ -467,6 +467,18 @@ void foo() {
   __typeof__(NSBundle2.foo2.weakProp) t5;
 }
 
+void testAuto() {
+  auto __weak wp = NSBundle2.foo2.weakProp;
+}
+
+void testLambdaCaptureInit() {
+  [capture(NSBundle2.foo2.weakProp)] {} ();
+}
+
+void testAutoNew() {
+  auto p = new auto(NSBundle2.foo2.weakProp);
+}
+
 // This used to crash in the constructor of WeakObjectProfileTy when a
 // DeclRefExpr was passed that didn't reference a VarDecl.