a734ab9808
Support the constexpr specifier on lambda expressions - and support its inference from the lambda call operator's body.
i.e.
auto L = [] () constexpr { return 5; };
static_assert(L() == 5); // OK
auto Implicit = [] (auto a) { return a; };
static_assert(Implicit(5) == 5);
We do not support evaluation of lambda's within constant expressions just yet.
Implementation Strategy:
- teach ParseLambdaExpressionAfterIntroducer to expect a constexpr specifier and mark the invented function call operator's declarator's decl-specifier with it; Have it emit fixits for multiple decl-specifiers (mutable or constexpr) in this location.
- for cases where constexpr is not explicitly specified, have buildLambdaExpr check whether the invented function call operator satisfies the requirements of a constexpr function, by calling CheckConstexprFunctionDecl/Body.
Much obliged to Richard Smith for his patience and his care, in ensuring the code is clang-worthy.
llvm-svn: 264513
32 lines
1.4 KiB
C++
32 lines
1.4 KiB
C++
// RUN: %clang_cc1 -std=c++1z %s -verify
|
|
// RUN: %clang_cc1 -std=c++14 %s -verify
|
|
// RUN: %clang_cc1 -std=c++11 %s -verify
|
|
|
|
|
|
auto XL0 = [] constexpr { }; //expected-error{{requires '()'}} expected-error{{expected body}}
|
|
auto XL1 = [] () mutable
|
|
mutable //expected-error{{cannot appear multiple times}}
|
|
mutable { }; //expected-error{{cannot appear multiple times}}
|
|
|
|
#if __cplusplus > 201402L
|
|
auto XL2 = [] () constexpr mutable constexpr { }; //expected-error{{cannot appear multiple times}}
|
|
auto L = []() mutable constexpr { };
|
|
auto L2 = []() constexpr { };
|
|
auto L4 = []() constexpr mutable { };
|
|
auto XL16 = [] () constexpr
|
|
mutable
|
|
constexpr //expected-error{{cannot appear multiple times}}
|
|
mutable //expected-error{{cannot appear multiple times}}
|
|
mutable //expected-error{{cannot appear multiple times}}
|
|
constexpr //expected-error{{cannot appear multiple times}}
|
|
constexpr //expected-error{{cannot appear multiple times}}
|
|
{ };
|
|
|
|
#else
|
|
auto L = []() mutable constexpr {return 0; }; //expected-warning{{is a C++1z extension}}
|
|
auto L2 = []() constexpr { return 0;};//expected-warning{{is a C++1z extension}}
|
|
auto L4 = []() constexpr mutable { return 0; }; //expected-warning{{is a C++1z extension}}
|
|
#endif
|
|
|
|
|