[Bug c++/94128] ICE on C++20 "requires requires" with lambda

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94128

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |10.0
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-03-11
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Is it really a valid code?
Started to ICE with r10-3735-gcb57504a55015891, before that we rejected the
code:

pr94128.cc:1:11: warning: use of ‘auto’ in parameter declaration only available
with ‘-fconcepts’
    1 | void test(auto param)
      |           ^~~~
pr94128.cc:2:3: error: ‘requires’ only available with ‘-fconcepts’
    2 |   requires requires{ { [](auto p){return p;}(param) }; };
      |   ^~~~~~~~
pr94128.cc:2:12: error: ‘requires’ was not declared in this scope
    2 |   requires requires{ { [](auto p){return p;}(param) }; };
      |            ^~~~~~~~
pr94128.cc: In function ‘void test(auto:1)’:
pr94128.cc:2:52: error: expected ‘;’ before ‘}’ token
    2 |   requires requires{ { [](auto p){return p;}(param) }; };
      |                                                    ^~