refactor: improve UFCS error messages #490

JohelEGP · 2023-06-02T23:02:34Z

Resolves #439.

See it working at https://compiler-explorer.com/z/7asaMGY9o.

Before and after

Clang before

build/_cppfront/main.cpp:185:13: error: use of undeclared identifier 'push_back'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |             ^
build/_cppfront/main.cpp:185:3: note: in instantiation of function template specialization 'main()::(anonymous class)::operator()<std::vector<int> &, const char (&)[5]>' requested here
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^
raw.githubusercontent.com/hsutter/cppfront/main/include/cpp2util.h:702:2: note: expanded from macro 'CPP2_UFCS'
  702 | }(PARAM1, __VA_ARGS__)
      |  ^
1 error generated.

Clang after

build/_cppfront/main.cpp:185:3: error: static assertion failed due to requirement 'ufcs_invocable': 
  UFCS candidates are invalid:
    1) vi.push_back("oops")
    2) push_back(vi, "oops")
  Calling them unconditionally to have them diagnosed.
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
build/_cppfront/main.cpp:40:27: note: expanded from macro 'CPP2_UFCS'
   40 |             static_assert(ufcs_invocable, \
      |                           ^~~~~~~~~~~~~~
build/_cppfront/main.cpp:185:3: note: in instantiation of function template specialization 'main()::(anonymous class)::operator()<std::vector<int> &, const char (&)[5]>' requested here
build/_cppfront/main.cpp:46:2: note: expanded from macro 'CPP2_UFCS'
   46 | }(PARAM1, __VA_ARGS__)
      |  ^
build/_cppfront/main.cpp:185:13: error: no matching member function for call to 'push_back'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
build/_cppfront/main.cpp:43:27: note: expanded from macro 'CPP2_UFCS'
   43 |         CPP2_FORWARD(obj).FUNCNAME(CPP2_FORWARD(params)...); \
      |         ~~~~~~~~~~~~~~~~~~^~~~~~~~
/opt/compiler-explorer/clang-trunk-20230602/bin/../include/c++/v1/vector:650:62: note: candidate function not viable: no known conversion from 'const char[5]' to 'const value_type' (aka 'const int') for 1st argument
  650 |     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void push_back(const_reference __x);
      |                                                              ^
/opt/compiler-explorer/clang-trunk-20230602/bin/../include/c++/v1/vector:652:62: note: candidate function not viable: no known conversion from 'const char[5]' to 'value_type' (aka 'int') for 1st argument
  652 |     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void push_back(value_type&& __x);
      |                                                              ^
build/_cppfront/main.cpp:185:13: error: use of undeclared identifier 'push_back'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |             ^
3 errors generated.

GCC before

In file included from /app/cpp2util.h:1,
                 from /app/build/_cppfront/main.cpp:3:
build/_cppfront/main.cpp: In instantiation of 'main()::<lambda(auto:85&&, auto:86&& ...)> [with auto:85 = std::vector<int>&; auto:86 = {const char (&)[5]}]':
build/_cppfront/main.cpp:185:3:   required from here
build/_cppfront/main.cpp:185:3: error: 'push_back' was not declared in this scope
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^

GCC after

build/_cppfront/main.cpp: In instantiation of 'main()::<lambda(auto:85&&, auto:86&& ...)> [with auto:85 = std::vector<int>&; auto:86 = {const char (&)[5]}]':
build/_cppfront/main.cpp:185:3:   required from here
build/_cppfront/main.cpp:40:27: error: static assertion failed: 
  UFCS candidates are invalid:
    1) vi.push_back("oops")
    2) push_back(vi, "oops")
  Calling them unconditionally to have them diagnosed.
   40 |             static_assert(ufcs_invocable, \
      |                           ^~~~~~~~~~~~~~
build/_cppfront/main.cpp:185:3: note: in expansion of macro 'CPP2_UFCS'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^~~~~~~~~
build/_cppfront/main.cpp:40:27: note: 'ufcs_invocable' evaluates to false
   40 |             static_assert(ufcs_invocable, \
      |                           ^~~~~~~~~~~~~~
build/_cppfront/main.cpp:185:3: note: in expansion of macro 'CPP2_UFCS'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^~~~~~~~~
build/_cppfront/main.cpp:43:35: error: no matching function for call to 'push_back(const char [5])'
   43 |         CPP2_FORWARD(obj).FUNCNAME(CPP2_FORWARD(params)...); \
      |                                   ^
build/_cppfront/main.cpp:185:3: note: in expansion of macro 'CPP2_UFCS'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^~~~~~~~~
In file included from /opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/vector:66,
                 from /app/raw.githubusercontent.com/hsutter/cppfront/main/include/cpp2util.h:206,
                 from /app/cpp2util.h:1,
                 from /app/build/_cppfront/main.cpp:3:
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1281:7: note: candidate: 'constexpr void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = int; _Alloc = std::allocator<int>; value_type = int]' (near match)
 1281 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1281:7: note:   conversion of argument 1 would be ill-formed:
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1281:7: error: invalid conversion from 'const char*' to 'std::vector<int>::value_type' {aka 'int'} [-fpermissive]
 1281 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
      |       |
      |       const char*
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1298:7: note: candidate: 'constexpr void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; value_type = int]' (near match)
 1298 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1298:7: note:   conversion of argument 1 would be ill-formed:
/opt/compiler-explorer/gcc-trunk-20230602/include/c++/14.0.0/bits/stl_vector.h:1298:7: error: invalid conversion from 'const char*' to 'std::vector<int>::value_type' {aka 'int'} [-fpermissive]
 1298 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
      |       |
      |       const char*
build/_cppfront/main.cpp:44:17: error: 'push_back' was not declared in this scope
   44 |         FUNCNAME(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
      |                 ^
build/_cppfront/main.cpp:185:3: note: in expansion of macro 'CPP2_UFCS'
  185 |   CPP2_UFCS(push_back, vi, "oops");
      |   ^~~~~~~~~

Testing summary.

99% tests passed, 1 tests failed out of 253

Total Test time (real) = 114.06 sec

The following tests FAILED:
  122 - build/pure2-bugfix-for-better-ufcs-error-messages (Failed)
Errors while running CTest

Acknowledgements.

Tested thanks to https://github.com/modern-cmake/cppfront.
The commit message uses Conventional Commits 1.0.0.

JohelEGP · 2023-06-03T01:44:15Z

What do you think about having a single UFCS macro: https://compiler-explorer.com/z/hbaacdf16?

Before

auto main() -> int{
  CPP2_UFCS(push_back, vi, "oops");
  CPP2_UFCS_0(push_back, vi);
  CPP2_UFCS_TEMPLATE(push_back, (<0>), vi, "oops");
  CPP2_UFCS_TEMPLATE_0(push_back, (<0>), vi);
  CPP2_UFCS_TEMPLATE(push_back, (<0,0>), vi, 0, 0);
}
cpp2::i32 i0 {CPP2_UFCS_NONLOCAL(push_back, vi, "oops")}; 
cpp2::i32 i1 {CPP2_UFCS_0_NONLOCAL(push_back, vi)}; 
cpp2::i32 i2 {CPP2_UFCS_TEMPLATE_NONLOCAL(push_back, (<0>), vi, "oops")}; 
cpp2::i32 i3 {CPP2_UFCS_TEMPLATE_0_NONLOCAL(push_back, (<0>), vi)}; 
cpp2::i32 i4 {CPP2_UFCS_TEMPLATE_NONLOCAL(push_back, (<0,0>), vi, 0, 0)};

After

() and (,) for comma can be gone pending #46 (comment).

auto main_() -> int {
  CPP2_UFCS(&,,(push_back),vi,(,),"oops");
  CPP2_UFCS(&,,(push_back),vi,());
  CPP2_UFCS(&,template,(push_back<0>),vi,(,),"oops");
  CPP2_UFCS(&,template,(push_back<0>),vi,());
  CPP2_UFCS(&,template,(push_back<0, 0>),vi,(,), 0, 0);
}
cpp2::i32 i5 {CPP2_UFCS(,,(push_back),vi,(,),"oops")};
cpp2::i32 i6 {CPP2_UFCS(,,(push_back),vi,())};
cpp2::i32 i7 {CPP2_UFCS(,template,(push_back<0>),vi,(,),"oops")};
cpp2::i32 i8 {CPP2_UFCS(,template,(push_back<0>),vi,())};
cpp2::i32 i9 {CPP2_UFCS(,template,(push_back<0, 0>),vi,(,), 0, 0)};

Or somewhere in-between.

JohelEGP · 2023-06-06T21:37:27Z

I think this should be superseded by the resolution for #497.
Here's the single UFCS macro with #497 fixed: https://compiler-explorer.com/z/KxavrccTc.

The error message on Clang is pretty good:

Relevant lines:

<source>:27:3: error: no matching function for call to object of type '(lambda at <source>:27:3)'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:27:3: note: candidate template ignored: constraints not satisfied [with obj:auto = std::vector<int> &, params:auto = <const char (&)[5]>]
<source>:27:17: note: because 'std::forward<decltype(obj)>(obj).push_back(std::forward<decltype(params)>(params)...)' would be invalid: no matching member function for call to 'push_back'
<source>:27:17: note: and 'push_back(std::forward<decltype(obj)>(obj), std::forward<decltype(params)>(params)...)' would be invalid: use of undeclared identifier 'push_back'

Full output:

<source>:27:3: error: no matching function for call to object of type '(lambda at <source>:27:3)'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:14:65: note: expanded from macro 'CPP2_UFCS'
   14 | #define CPP2_UFCS(LAMBDADEFCAPT,TEMPKW,FUNCID,PARAM1,COMMA,...) \
      |                                                                 ^
   15 | [LAMBDADEFCAPT](auto&& obj, auto&& ...params) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   18 |     if constexpr (requires{ CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); }) { \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   19 |         return CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   20 |     } else { \
      |     ~~~~~~~~~~
   21 |         return CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   22 |     } \
      |     ~~~
<source>:27:3: note: candidate template ignored: constraints not satisfied [with obj:auto = std::vector<int> &, params:auto = <const char (&)[5]>]
<source>:14:65: note: expanded from macro 'CPP2_UFCS'
   14 | #define CPP2_UFCS(LAMBDADEFCAPT,TEMPKW,FUNCID,PARAM1,COMMA,...) \
      |                                                                 ^
<source>:27:17: note: because 'std::forward<decltype(obj)>(obj).push_back(std::forward<decltype(params)>(params)...)' would be invalid: no matching member function for call to 'push_back'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |                 ^
<source>:27:17: note: and 'push_back(std::forward<decltype(obj)>(obj), std::forward<decltype(params)>(params)...)' would be invalid: use of undeclared identifier 'push_back'

GCC with `-fconcepts-diagnostics-depth=2`:

Relevant lines:

<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>: In substitution of 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)> [with auto:85 = std::vector<int>&; auto:86 = {const char (&)[5]}]':
<source>:16:76: note: the required expression 'forward<decltype (obj)>(obj).push_back((forward<decltype(params)>)(params)...)' is invalid
<source>:17:54: note: the required expression 'push_back(forward<decltype (obj)>(obj), (forward<decltype(params)>)(params)...)' is invalid

Full output:

<source>:23:2: error: no match for call to '(main_()::<lambda(auto:85&&, auto:86&& ...)>) (std::vector<int>&, const char [5])'
   15 | [LAMBDADEFCAPT](auto&& obj, auto&& ...params) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   18 |     if constexpr (requires{ CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); }) { \
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   19 |         return CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   20 |     } else { \
      |     ~~~~~~~~~~
   21 |         return CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   22 |     } \
      |     ~~~
   23 | }(PARAM1 CPP2_UFCS_REMPARENS COMMA __VA_ARGS__)
      | ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:15:1: note: candidate: 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)>'
   15 | [LAMBDADEFCAPT](auto&& obj, auto&& ...params) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
      | ^
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:15:1: note:   template argument deduction/substitution failed:
   15 | [LAMBDADEFCAPT](auto&& obj, auto&& ...params) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
      | ^
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:15:1: note: constraints not satisfied
   15 | [LAMBDADEFCAPT](auto&& obj, auto&& ...params) CPP2_FORCE_INLINE_LAMBDA -> decltype(auto) \
      | ^
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>: In substitution of 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)> [with auto:85 = std::vector<int>&; auto:86 = {const char (&)[5]}]':
<source>:27:3:   required from here
<source>:27:3:   required by the constraints of 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)>'
<source>:17:14: note: no operand of the disjunction is satisfied
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:16:14: note: the operand 'requires{(forward<decltype(obj)>)(obj).push_back((forward<decltype(params)>)(params)...);}' is unsatisfied because
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:27:3:   required by the constraints of 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)>'
<source>:27:3:   in requirements  [with auto:85 = std::vector<int, std::allocator<int> >&; auto:86 = {const char (&)[5]}]
<source>:16:76: note: the required expression 'forward<decltype (obj)>(obj).push_back((forward<decltype(params)>)(params)...)' is invalid
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:17:17: note: the operand 'requires{push_back((forward<decltype(obj)>)(obj), (forward<decltype(params)>)(params)...);}' is unsatisfied because
   16 |     requires requires { CPP2_FORWARD(obj).TEMPKW CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(params)...); } \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
<source>:27:3:   required by the constraints of 'template<class auto:85, class ... auto:86> main_()::<lambda(auto:85&&, auto:86&& ...)>'
<source>:27:3:   in requirements  [with auto:85 = std::vector<int, std::allocator<int> >&; auto:86 = {const char (&)[5]}]
<source>:17:54: note: the required expression 'push_back(forward<decltype (obj)>(obj), (forward<decltype(params)>)(params)...)' is invalid
   17 |              || requires { CPP2_UFCS_REMPARENS FUNCID(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } { \
      |                                                      ^
<source>:27:3: note: in expansion of macro 'CPP2_UFCS'
   27 |   CPP2_UFCS(&,,(push_back),vi,(,),"oops");
      |   ^~~~~~~~~
cc1plus: note: set '-fconcepts-diagnostics-depth=' to at least 3 for more detail

MSVC:

Full output:

<source>(27): error C3889: call to object of class type 'main_::<lambda_1>': no matching call operator found
<source>(27): note: could be 'decltype(auto) main_::<lambda_1>::operator ()(_T1 &&,_T2 &&...) const'
<source>(27): note: Failed to specialize function template 'decltype(auto) main_::<lambda_1>::operator ()(_T1 &&,_T2 &&...) const'
<source>(27): note: With the following template arguments:
<source>(27): note: '_T1=std::vector<int,std::allocator<int>> &'
<source>(27): note: '_T2={const char (&)[5]}'

JohelEGP · 2023-08-11T04:48:33Z

Marking as draft to prevent merging
as this should be superseded by #506.

JohelEGP · 2023-09-05T15:38:10Z

I think this should be superseded by the resolution for #497.

JohelEGP added 2 commits June 2, 2023 18:58

refactor: improve UFCS error messages

cbaf990

refactor: compute expressions at call site

5256b1b

This was referenced Jun 7, 2023

[BUG] Lowered UFCS doesn't SFINAE #497

Closed

fix(util): handle known UFCS corner cases #506

Merged

JohelEGP marked this pull request as draft August 11, 2023 04:48

JohelEGP closed this Sep 5, 2023

JohelEGP deleted the ufcs_error_message branch September 5, 2023 15:38

JohelEGP mentioned this pull request Mar 16, 2024

Add UFCS failure case error diagnostics #1023

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refactor: improve UFCS error messages #490

refactor: improve UFCS error messages #490

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JohelEGP commented Sep 5, 2023

refactor: improve UFCS error messages #490

refactor: improve UFCS error messages #490

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