[Bug c++/100716] member function template parameter should never be printed in candidate list and "T = T" should never be shown in substitutions

["kretz at kde dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100716

--- Comment #3 from Matthias Kretz (Vir) <kretz at kde dot org> ---
Created attachment 50877
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50877&action=edit
proposed patch

Ensure dump_template_decl for function templates never prints template
parameters after the function name (it did with -fno-pretty-templates)
and skip output of irrelevant & confusing "[with T = T]" in
dump_substitution.

gcc/cp/ChangeLog:

        PR c++/100716
        * error.c (dump_template_bindings): Include code to print
        "[with" and ']', conditional on whether anything is printed at
        all. This is tied to whether a semicolon is needed to separate
        multiple template parameters. If the template argument repeats
        the template parameter (T = T), then skip the parameter.
        (dump_substitution): Moved code to print "[with" and ']' to
        dump_template_bindings.
        (dump_function_decl): Partial revert of PR50828, which masked
        TFF_TEMPLATE_NAME for all of dump_function_decl. Now
        TFF_TEMPLATE_NAME is masked for the scope of the function and
        only carries through to dump_function_name.
        (dump_function_name): Avoid calling dump_template_parms if
        TFF_TEMPLATE_NAME is set.

gcc/testsuite/ChangeLog:

        PR c++/100716
        * g++.dg/diagnostic/pr100716.C: New test.
        * g++.dg/diagnostic/pr100716-1.C: Same test with
        -fno-pretty-templates.
---
 gcc/cp/error.c                               | 59 +++++++++++++++-----
 gcc/testsuite/g++.dg/diagnostic/pr100716-1.C | 54 ++++++++++++++++++
 gcc/testsuite/g++.dg/diagnostic/pr100716.C   | 54 ++++++++++++++++++
 3 files changed, 152 insertions(+), 15 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/diagnostic/pr100716-1.C
 create mode 100644 gcc/testsuite/g++.dg/diagnostic/pr100716.C