diff options
author | Faisal Vali <faisalv@yahoo.com> | 2016-03-21 09:25:37 +0000 |
---|---|---|
committer | Faisal Vali <faisalv@yahoo.com> | 2016-03-21 09:25:37 +0000 |
commit | 6078347237c150cf1f3a7cfd37129e31207d6325 (patch) | |
tree | af46b5e625ad1cf65c4325ea68bcd04e2665d556 /lib/Parse/ParseExprCXX.cpp | |
parent | 0b2ac6214c4ba0ed23916d552a07ec8acdb744c0 (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!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@263921 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Parse/ParseExprCXX.cpp')
-rw-r--r-- | lib/Parse/ParseExprCXX.cpp | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp index 558d2371f6..8e5f35ad65 100644 --- a/lib/Parse/ParseExprCXX.cpp +++ b/lib/Parse/ParseExprCXX.cpp @@ -846,8 +846,16 @@ Optional<unsigned> Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro, IdentifierInfo *Id = nullptr; SourceLocation EllipsisLoc; ExprResult Init; - - if (Tok.is(tok::kw_this)) { + + if (Tok.is(tok::star)) { + Loc = ConsumeToken(); + if (Tok.is(tok::kw_this)) { + ConsumeToken(); + Kind = LCK_StarThis; + } else { + return DiagResult(diag::err_expected_star_this_capture); + } + } else if (Tok.is(tok::kw_this)) { Kind = LCK_This; Loc = ConsumeToken(); } else { |