diff options
author | Faisal Vali <faisalv@yahoo.com> | 2016-03-21 09:25:37 +0000 |
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committer | Faisal Vali <faisalv@yahoo.com> | 2016-03-21 09:25:37 +0000 |
commit | dc6b596ebbd3c594c75fc6c6bc6cb7c14fdcec24 (patch) | |
tree | 22cb8f82b4795afc128f86720b6ca4f148211e8f /clang/lib/AST/StmtPrinter.cpp | |
parent | 2c8b5993bebd0b5523e254a06f82322c46f1221b (diff) |
[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
Diffstat (limited to 'clang/lib/AST/StmtPrinter.cpp')
-rw-r--r-- | clang/lib/AST/StmtPrinter.cpp | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp index 6938aef57eaf..cc3837409269 100644 --- a/clang/lib/AST/StmtPrinter.cpp +++ b/clang/lib/AST/StmtPrinter.cpp @@ -2008,7 +2008,9 @@ void StmtPrinter::VisitLambdaExpr(LambdaExpr *Node) { case LCK_This: OS << "this"; break; - + case LCK_StarThis: + OS << "*this"; + break; case LCK_ByRef: if (Node->getCaptureDefault() != LCD_ByRef || Node->isInitCapture(C)) OS << '&'; |