[Bug c/59870] Gcc should warn conversion from "const char*" to "char*" for string literals

["pinskia at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59870

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Chengnian Sun from comment #6)
> (In reply to Harald van Dijk from comment #2)
> > The type of a string literal in C is char[N], unlike in C++ where it is
> > const char[N]. clang's -Weverything option enables -Wwrite-strings, which
> > changes the type const char[N] and because of that makes the compiler not
> > conform to the C standard. The same -Wwrite-strings option also exists in
> > GCC already (in fact, I would be surprised if clang's name for the option
> > didn't come from GCC), so I don't think there's anything in GCC that needs
> > changing.
> > 
> > $ gcc -Wwrite-strings test.c
> > test.c: In function âmainâ:
> > test.c:4:19: warning: initialization discards âconstâ qualifier from pointer
> > target type [enabled by default]
> >          char* s = "test";
> >                    ^
> 
> 
> 
> Yes, this option works. 
> 
> However, one more question. Does "[enabled by default]" imply that this type
> of warnings is enabled by default? If yes, then it is inconsistent with the
> current setting of GCC flags (i.e., this flag should be explicitly enabled).

Please re-read comment #2.  -Wwrite-strings changes the type of string literals
to be const char[] rather than char[] as what the standard points out it should
be.  The warning that is enabled by default is the one which warns about
discarding const qualifier.