From dc6b596ebbd3c594c75fc6c6bc6cb7c14fdcec24 Mon Sep 17 00:00:00 2001 From: Faisal Vali Date: Mon, 21 Mar 2016 09:25:37 +0000 Subject: [Cxx1z] Implement Lambda Capture of *this by Value as [=,*this] (P0018R3) Implement lambda capture of *this by copy. For e.g.: struct A { int d = 10; auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; } }; auto L = A{}.foo(); // A{}'s lifetime is gone. // Below is still ok, because *this was captured by value. assert(L(10) == 20); assert(L(100) == 120); If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined. Implementation Strategy: - amend the parser to accept *this in the lambda introducer - add a new king of capture LCK_StarThis - teach Sema::CheckCXXThisCapture to handle by copy captures of the enclosing object (i.e. *this) - when CheckCXXThisCapture does capture by copy, the corresponding initializer expression for the closure's data member direct-initializes it thus making a copy of '*this'. - in codegen, when assigning to CXXThisValue, if *this was captured by copy, make sure it points to the corresponding field member, and not, unlike when captured by reference, what the field member points to. - mark feature as implemented in svn Much gratitude to Richard Smith for his carefully illuminating reviews! llvm-svn: 263921 --- clang/lib/Serialization/ASTReaderDecl.cpp | 1 + 1 file changed, 1 insertion(+) (limited to 'clang/lib/Serialization/ASTReaderDecl.cpp') diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp index 1e93627df8d..e580eb03e85 100644 --- a/clang/lib/Serialization/ASTReaderDecl.cpp +++ b/clang/lib/Serialization/ASTReaderDecl.cpp @@ -1497,6 +1497,7 @@ void ASTDeclReader::ReadCXXDefinitionData( bool IsImplicit = Record[Idx++]; LambdaCaptureKind Kind = static_cast(Record[Idx++]); switch (Kind) { + case LCK_StarThis: case LCK_This: case LCK_VLAType: *ToCapture++ = Capture(Loc, IsImplicit, Kind, nullptr,SourceLocation()); -- cgit v1.2.3