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IS C++20 concepts support on the roadmap? #31
Description
Will c++20 concept support be added, if using gcc -std=c++2a -fconcepts or the clang saarraz fork with concepts? If so, any timeframe on that? I have no idea if it's implementable, and if so, how hard it would be. (Template metaprogramming makes my head hurt, and I can't believe you've been able to do what you have with this!)
This compiles, with a manual injection of a realFoo, if the make<...> line is removed:
#include "GUnit.h"
using namespace testing;
template<typename T>
concept bool Fooable = requires(T a) {
{ a.foo() } -> int;
};
class realFoo {
public:
int foo() {
return 0;
}
};
template<Fooable foo>
class underTest {
public:
underTest(foo x) : x{x} {
}
private:
foo x;
};
GTEST("Concepts") {
realFoo foo;
underTest manualUt{foo};
auto [ut, mocks] = make<underTest, StrictGMock>();
}
With the line, gcc from git master gives:
concepts.gpp: In member function ‘void GTEST<testing::v1::detail::string<'\"', 'C', 'o', 'n', 'c', 'e', 'p', 't', 's', '\"', '\000'>, testing::v1::detail::string<> >::TestBodyImpl(testing::v1::detail::TestRun&)’:
concepts.gpp:28:52: error: no matching function for call to ‘make<template<class foo> requires Fooable<foo> class underTest, template<class T> using StrictGMock = testing::StrictMock<testing::v1::GMock<T> > >()’
28 | auto [ut, mocks] = make<underTest, StrictGMock>();
| ^
In file included from include/GUnit.h:10,
from concepts.gpp:1:
include/GUnit/GMake.h:433:6: note: candidate: ‘template<class T, class ... TArgs> auto testing::v1::make(TArgs&& ...)’
433 | auto make(TArgs &&... args) {
| ^~~~
include/GUnit/GMake.h:433:6: note: template argument deduction/substitution failed:
include/GUnit/GMake.h:444:6: note: candidate: ‘template<class T, template<class> class TMock, class ... TMocks, typename std::enable_if<(testing::v1::detail::is_gmock<TMock>::value && std::is_same<testing::v1::detail::bool_list<testing::v1::detail::always<TMocks>::value ...>, testing::v1::detail::bool_list<testing::v1::detail::is_gmock_type<TMocks>::value
...> >::value), int>::type <anonymous>, class ... TArgs> auto testing::v1::make(TArgs&& ...)’
444 | auto make(TArgs &&... args) {
| ^~~~
include/GUnit/GMake.h:444:6: note: template argument deduction/substitution failed:
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