From ec38cf7aed74a354d6cbcd4fa99f4490406b467b Mon Sep 17 00:00:00 2001 From: George Karpenkov Date: Thu, 29 Mar 2018 00:56:24 +0000 Subject: [PATCH] [ast] Do not auto-initialize Objective-C for-loop variables in Objective-C++ in templatized code under ARC MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The AST for the fragment ``` @interface I @end template void decode(I *p) { for (I *k in p) {} } void decode(I *p) { decode(p); } ``` differs heavily when templatized and non-templatized: ``` |-FunctionTemplateDecl 0x7fbfe0863940 line:5:6 decode | |-TemplateTypeParmDecl 0x7fbfe0863690 col:11 typename depth 0 index 0 | |-FunctionDecl 0x7fbfe08638a0 line:5:6 decode 'void (I *__strong)' | | |-ParmVarDecl 0x7fbfe08637a0 col:16 referenced p 'I *__strong' | | `-CompoundStmt 0x7fbfe0863b88 | |   `-ObjCForCollectionStmt 0x7fbfe0863b50 | |     |-DeclStmt 0x7fbfe0863a50 | |     | `-VarDecl 0x7fbfe08639f0 col:11 k 'I *const __strong' | |     |-ImplicitCastExpr 0x7fbfe0863a90 'I *' | |     | `-DeclRefExpr 0x7fbfe0863a68 'I *__strong' lvalue ParmVar 0x7fbfe08637a0 'p' 'I *__strong' | |     `-CompoundStmt 0x7fbfe0863b78 | `-FunctionDecl 0x7fbfe0863f80 line:5:6 used decode 'void (I *__strong)' |   |-TemplateArgument type 'int' |   |-ParmVarDecl 0x7fbfe0863ef8 col:16 used p 'I *__strong' |   `-CompoundStmt 0x7fbfe0890cf0 |     `-ObjCForCollectionStmt 0x7fbfe0890cc8 |       |-DeclStmt 0x7fbfe0890c70 |       | `-VarDecl 0x7fbfe0890c00 col:11 k 'I *__strong' callinit |       |   `-ImplicitValueInitExpr 0x7fbfe0890c60 <> 'I *__strong' |       |-ImplicitCastExpr 0x7fbfe0890cb0 'I *' |       | `-DeclRefExpr 0x7fbfe0890c88 'I *__strong' lvalue ParmVar 0x7fbfe0863ef8 'p' 'I *__strong' |       `-CompoundStmt 0x7fbfe0863b78 ``` Note how in the instantiated version ImplicitValueInitExpr unexpectedly appears. While objects are auto-initialized under ARC, it does not make sense to have an initializer for a for-loop variable, and it makes even less sense to have such a different AST for instantiated and non-instantiated version. Digging deeper, I have found that there are two separate Sema* files for dealing with templates and for dealing with non-templatized code. In a non-templatized version, an initialization was performed only for variables which are not loop variables for an Objective-C loop and not variables for a C++ for-in loop: ```   if (FRI && (Tok.is(tok::colon) || isTokIdentifier_in())) {     bool IsForRangeLoop = false;     if (TryConsumeToken(tok::colon, FRI->ColonLoc)) {       IsForRangeLoop = true;       if (Tok.is(tok::l_brace))         FRI->RangeExpr = ParseBraceInitializer();       else         FRI->RangeExpr = ParseExpression();     }     Decl *ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);     if (IsForRangeLoop)       Actions.ActOnCXXForRangeDecl(ThisDecl);     Actions.FinalizeDeclaration(ThisDecl);     D.complete(ThisDecl);     return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, ThisDecl);   }   SmallVector DeclsInGroup;   Decl *FirstDecl = ParseDeclarationAfterDeclaratorAndAttributes(       D, ParsedTemplateInfo(), FRI); ``` However the code in SemaTemplateInstantiateDecl was inconsistent, guarding only against C++ for-in loops. rdar://38391075 Differential Revision: https://reviews.llvm.org/D44989 llvm-svn: 328749 --- clang/include/clang/AST/Decl.h | 13 +++++++++++++ clang/lib/Parse/ParseDecl.cpp | 7 ++++++- clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 3 ++- clang/lib/Serialization/ASTReaderDecl.cpp | 1 + clang/lib/Serialization/ASTWriterDecl.cpp | 2 ++ clang/test/SemaObjC/foreachtemplatized.mm | 15 +++++++++++++++ 6 files changed, 39 insertions(+), 2 deletions(-) create mode 100644 clang/test/SemaObjC/foreachtemplatized.mm diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h index 44d2030b4f62..da164c66a619 100644 --- a/clang/include/clang/AST/Decl.h +++ b/clang/include/clang/AST/Decl.h @@ -937,6 +937,9 @@ protected: /// for-range statement. unsigned CXXForRangeDecl : 1; + /// Whether this variable is the for-in loop declaration in Objective-C. + unsigned ObjCForDecl : 1; + /// Whether this variable is an ARC pseudo-__strong /// variable; see isARCPseudoStrong() for details. unsigned ARCPseudoStrong : 1; @@ -1334,6 +1337,16 @@ public: NonParmVarDeclBits.CXXForRangeDecl = FRD; } + /// \brief Determine whether this variable is a for-loop declaration for a + /// for-in statement in Objective-C. + bool isObjCForDecl() const { + return NonParmVarDeclBits.ObjCForDecl; + } + + void setObjCForDecl(bool FRD) { + NonParmVarDeclBits.ObjCForDecl = FRD; + } + /// \brief Determine whether this variable is an ARC pseudo-__strong /// variable. A pseudo-__strong variable has a __strong-qualified /// type but does not actually retain the object written into it. diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp index f19bcaadf015..0e02acd85958 100644 --- a/clang/lib/Parse/ParseDecl.cpp +++ b/clang/lib/Parse/ParseDecl.cpp @@ -2027,8 +2027,13 @@ Parser::DeclGroupPtrTy Parser::ParseDeclGroup(ParsingDeclSpec &DS, } Decl *ThisDecl = Actions.ActOnDeclarator(getCurScope(), D); - if (IsForRangeLoop) + if (IsForRangeLoop) { Actions.ActOnCXXForRangeDecl(ThisDecl); + } else { + // Obj-C for loop + if (auto *VD = dyn_cast_or_null(ThisDecl)) + VD->setObjCForDecl(true); + } Actions.FinalizeDeclaration(ThisDecl); D.complete(ThisDecl); return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, ThisDecl); diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 9e09a6aa3569..a7883c67b808 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -4083,6 +4083,7 @@ void Sema::BuildVariableInstantiation( NewVar->setTSCSpec(OldVar->getTSCSpec()); NewVar->setInitStyle(OldVar->getInitStyle()); NewVar->setCXXForRangeDecl(OldVar->isCXXForRangeDecl()); + NewVar->setObjCForDecl(OldVar->isObjCForDecl()); NewVar->setConstexpr(OldVar->isConstexpr()); NewVar->setInitCapture(OldVar->isInitCapture()); NewVar->setPreviousDeclInSameBlockScope( @@ -4215,7 +4216,7 @@ void Sema::InstantiateVariableInitializer( } // We'll add an initializer to a for-range declaration later. - if (Var->isCXXForRangeDecl()) + if (Var->isCXXForRangeDecl() || Var->isObjCForDecl()) return; ActOnUninitializedDecl(Var); diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp index 0c9151cf80a3..fa0db51e7f31 100644 --- a/clang/lib/Serialization/ASTReaderDecl.cpp +++ b/clang/lib/Serialization/ASTReaderDecl.cpp @@ -1279,6 +1279,7 @@ ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) { VD->NonParmVarDeclBits.ExceptionVar = Record.readInt(); VD->NonParmVarDeclBits.NRVOVariable = Record.readInt(); VD->NonParmVarDeclBits.CXXForRangeDecl = Record.readInt(); + VD->NonParmVarDeclBits.ObjCForDecl = Record.readInt(); VD->NonParmVarDeclBits.ARCPseudoStrong = Record.readInt(); VD->NonParmVarDeclBits.IsInline = Record.readInt(); VD->NonParmVarDeclBits.IsInlineSpecified = Record.readInt(); diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp index 254b5175d7bd..06ea8e7f2bcd 100644 --- a/clang/lib/Serialization/ASTWriterDecl.cpp +++ b/clang/lib/Serialization/ASTWriterDecl.cpp @@ -920,6 +920,7 @@ void ASTDeclWriter::VisitVarDecl(VarDecl *D) { Record.push_back(D->isExceptionVariable()); Record.push_back(D->isNRVOVariable()); Record.push_back(D->isCXXForRangeDecl()); + Record.push_back(D->isObjCForDecl()); Record.push_back(D->isARCPseudoStrong()); Record.push_back(D->isInline()); Record.push_back(D->isInlineSpecified()); @@ -2031,6 +2032,7 @@ void ASTWriter::WriteDeclAbbrevs() { Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isExceptionVariable Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isNRVOVariable Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isCXXForRangeDecl + Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isObjCForDecl Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isARCPseudoStrong Abv->Add(BitCodeAbbrevOp(0)); // isInline Abv->Add(BitCodeAbbrevOp(0)); // isInlineSpecified diff --git a/clang/test/SemaObjC/foreachtemplatized.mm b/clang/test/SemaObjC/foreachtemplatized.mm new file mode 100644 index 000000000000..ab2770a7cefb --- /dev/null +++ b/clang/test/SemaObjC/foreachtemplatized.mm @@ -0,0 +1,15 @@ +// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -Wno-objc-root-class -std=c++11 -ast-dump %s | FileCheck %s + +// CHECK-NOT: ImplicitValueInitExpr + +@interface I +@end + +template +void decode(I *p) { + for (I *k in p) {} +} + +void decode(I *p) { + decode(p); +}