[Bug preprocessor/77810] provide format_inform_at_substring to go with format_warning_at_substring

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77810

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |egallager at gcc dot gnu.org

--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> ---
Redoing https://gcc.gnu.org/ml/gcc-bugs/2017-08/msg01655.html

--- Comment #4 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Patch looks reasonable, and I can approve it.

CC me on it when you post it to gcc-patches.