[Bug c++/104584] New: Bad diagnostic

[Theodore.Papadopoulo at inria dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104584

            Bug ID: 104584
           Summary: Bad diagnostic
           Product: gcc
           Version: 11.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Theodore.Papadopoulo at inria dot fr
  Target Milestone: ---

Created attachment 52462
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52462&action=edit
A small test program

The attached code give a poor diagnostic hinting at a wrong number of arguments
instead of stating a non valid first argument as in the one argument case which
says "template argument 1 is invalid".

mururoa-> g++ test.C
test.C:4:33: error: wrong number of template arguments (1, should be 2)
    4 | typedef A<constexpr int,unsigned> B;
      |                                 ^
test.C:2:7: note: provided for ‘template<class T1, class T2> class A’
    2 | class A { };