Hi Akira,
I've reverted this in r359066. This subtly breaks the semantics of C++
initializers by strripping off an outer level of parentheses / braces
in some cases. Testcase:
struct A {
A();
A(const A&) = delete;
};
auto x = [a{A()}] {};
(This should be accepted in C++17 mode onwards, but this patch rejects
it by losing the braces around the A() expression.)
Moreover, I think this is fundamentally the wrong approach:
DeduceAutoType should not ever be changing the initializer expression
(and it certainly shouldn't expect those changes to stick around).
Instead, we should check for a placeholder type before attempting
deduction, just like we correct typos in the initializer before
attempting deduction.
On Thu, 10 Jan 2019 at 21:01, Akira Hatanaka via cfe-commits
<cfe-commits@lists.llvm.org> wrote:
>
> Author: ahatanak
> Date: Thu Jan 10 20:57:34 2019
> New Revision: 350917
>
> URL: http://llvm.org/viewvc/llvm-project?rev=350917&view=rev
> Log:
> [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
>
> Modified:
> cfe/trunk/include/clang/Sema/Sema.h
> cfe/trunk/lib/Sema/SemaDecl.cpp
> cfe/trunk/lib/Sema/SemaExprCXX.cpp
> cfe/trunk/lib/Sema/SemaLambda.cpp
> cfe/trunk/test/SemaObjC/arc-repeated-weak.mm
>
> Modified: cfe/trunk/include/clang/Sema/Sema.h
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=350917&r1=350916&r2=350917&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Sema/Sema.h (original)
> +++ cfe/trunk/include/clang/Sema/Sema.h Thu Jan 10 20:57:34 2019
> @@ -1960,7 +1960,7 @@ public:
> 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 @@ public:
> QualType deduceVarTypeFromInitializer(VarDecl *VDecl, DeclarationName Name,
> QualType Type, TypeSourceInfo *TSI,
> SourceRange Range, bool DirectInit,
> - Expr *Init);
> + Expr *&Init);
>
> TypeLoc getReturnTypeLoc(FunctionDecl *FD) const;
>
>
> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=350917&r1=350916&r2=350917&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Jan 10 20:57:34 2019
> @@ -10812,7 +10812,7 @@ QualType Sema::deduceVarTypeFromInitiali
> 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::deduceVarTypeFromInitiali
> << (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::deduceVarTypeFromInitiali
> }
>
> 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 *
> 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
>
> Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=350917&r1=350916&r2=350917&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Thu Jan 10 20:57:34 2019
> @@ -1865,12 +1865,11 @@ Sema::BuildCXXNew(SourceRange Range, boo
> 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;
>
> Modified: cfe/trunk/lib/Sema/SemaLambda.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLambda.cpp?rev=350917&r1=350916&r2=350917&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaLambda.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaLambda.cpp Thu Jan 10 20:57:34 2019
> @@ -759,14 +759,15 @@ QualType Sema::buildLambdaInitCaptureIni
> 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::buildLambdaInitCaptureIni
> : 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);
>
> Modified: cfe/trunk/test/SemaObjC/arc-repeated-weak.mm
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/arc-repeated-weak.mm?rev=350917&r1=350916&r2=350917&view=diff
> ==============================================================================
> --- cfe/trunk/test/SemaObjC/arc-repeated-weak.mm (original)
> +++ cfe/trunk/test/SemaObjC/arc-repeated-weak.mm Thu Jan 10 20:57:34 2019
> @@ -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.
>
>
>
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