Summary:
This patch rewrites the C++03 `__invoke` and related meta-programming. There are a number of major changes.
`__invoke` in C++03 now has a fallback overload for when the invoke expression is ill-formed (similar to C++11). This means that the `__invoke_return` traits will return `__nat` when `__invoke(...)` is ill formed. This would previously cause a compile error.
Bullets 1-4 of `__invoke` have been rewritten. In the old version `__invoke` had 32 overloads for bullets 1 and 2,
one for each possible cv-qualified function signature with arities 0-3. 64 overloads would be needed to support member functions
with varargs. Currently these overloads were fundamentally broken. An example overload looked like:
```
template <class Rp, class Tp, class T1, class A0>
Rp __invoke(Rp (Tp::*pm)(A0) const, T1&, A0&)
```
Because `A0` appeared in two different deducible contexts it would have to deduce to be an exact match or the overload
would be rejected. This is made even worse because `A0` appears without a reference qualifier in the member function signature
and with a reference qualifier as an `__invoke` parameter. This means that only member functions that took all
of their arguments by value could be matched.
One possible fix would be to make the second occurrence of `A0` appear in a non-deducible context. This way
any type convertible to `A0` could be passed as the first parameter. The benefit of this approach is that the
signature of the member function enforces the arity and types taken by the `__invoke` signature it generates. However
nothing in the `INVOKE` specification requires this behavior.
My solution is to use a `__invoke_enable_if<PM_Type, Tp>` metafunction to selectively enable the `__invoke` overloads for bullets 1, 2, 3 and 4. It uses `__member_function_traits` to inspect and extract the return type and class type of the pointer to member. Using `__member_function_traits` to inspect `PM_Type` also allows us to reduce the number of `__invoke` overloads from 32 to 8 and add
varargs support at the same time.
Because `__invoke_enable_if` knows the exact return type of `__invoke` for bullets 1-4 we no longer need to use `decltype(__invoke(...))` to
compute the return type in the `__invoke_return*` traits. This will reduce the problems caused by `#define decltype(X) __typeof__(X)` in C++03.
Tests for this change have already been committed. All tests in `test/std/utilities/function.objects` now pass in C++03, previously there were 20 failures.
Reviewers: K-ballo, howard.hinnant, mclow.lists
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D11553
llvm-svn: 246068
This patch removes a large amount of duplicate code found in both
<__functional_base> and <__functional_base_03>. The only code that remains
in <__functional_base_03> is the C++03 implementation of __invoke and
__invoke_return.
llvm-svn: 242951
Summary:
This patch adds the `<experimental/tuple>` header (almost) as specified in the latest draft of the library fundamentals TS.
The main changes in this patch are:
1. Added variable template `tuple_size_v`
2. Added function `apply(Func &&, Tuple &&)`.
3. Changed `__invoke` to be `_LIBCPP_CONSTEXPR_AFTER_CXX11`.
The `apply(...)` implementation uses `__invoke` to invoke the given function. `__invoke` already provides the required functionality. Using `__invoke` also allows `apply` to be used on pointers to member function/objects as an extension. In order to facilitate this `__invoke` has to be marked `constexpr`.
Test Plan:
Each new feature was tested.
The test cases for `tuple_size_v` are as follows:
1. tuple_size_v.pass.cpp
- Check `tuple_size_v` on cv qualified tuples, pairs and arrays.
2. tuple_size_v.fail.cpp
- Test on reference type.
3. tuple_size_v_2.fail.cpp
- Test on non-tuple
4. tuple_size_v_3.fail.cpp
- Test on pointer type.
The test cases for tuple.apply are as follows:
1. arg_type.pass.cpp
- Ensure that ref/pointer/cv qualified types are properly passed.
2. constexpr_types.pass.cpp
- Ensure constexpr evaluation of apply is possible for `tuple` and `pair`.
3. extended_types.pass.cpp
- Test apply on function types permitted by extension.
4. large_arity.pass.cpp
- Test that apply can evaluated on tuples and arrays with large sizes.
5. ref_qualifiers.pass.cpp
- Test that apply respects ref qualified functions.
6. return_type.pass.cpp
- Test that apply returns the proper type.
7. types.pass.cpp
- Test apply on function types as required by LFTS.
Reviewers: mclow.lists
Reviewed By: mclow.lists
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D4512
llvm-svn: 232515
Summary:
The bug can be found here: http://llvm.org/bugs/show_bug.cgi?id=22468
`__invoke_void_return_wrapper` is needed to properly handle calling a function that returns a value but where the std::function return type is void. Without this '-Wsystem-headers' will cause `function::operator()(...)` to not compile.
Reviewers: eugenis, K-ballo, mclow.lists
Reviewed By: mclow.lists
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D7444
llvm-svn: 228705
Eric Fiselier