[Bug c++/77922] Bogus suggestion: ‘constexpr’ does not name a type; did you mean ‘constexpr’?

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77922

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
A similar thing happens with other C++11 keywords:

bad.cc:1:1: warning: identifier ‘decltype’ is a keyword in C++11
[-Wc++11-compat]
 decltype i = 0;
 ^~~~~~~~
bad.cc:1:1: error: ‘decltype’ does not name a type; did you mean ‘decltype’?
 decltype i = 0;
 ^~~~~~~~
 decltype

It's even worse in this case, because the code isn't valid even in C++11, so
the fix-it can never be a useful change.

(In reply to Jakub Jelinek from comment #0)
> I'd say we should just not print the bogus "did you mean" if the identifier
> fuzzy matching found is the same as the one used originally.  Or not add
> constexpr into the suggestions in this case because it is not C++98?

Not adding non-C++98 keywords into the suggestions make sense, and would solve
both of these examples. (Another option for the constexpr case would be to
suggest dropping the -std=c++98/-std=gnu++98/-std=c++03/-std=gnu++03/-ansi
option).

If there are still other ways that the match could end up being the same as the
original then suppressing the "did you mean" would still make sense.