Re: libgettext.h (Re: Documentation of ngettext)

[Bruno Haible]

Alexandre Duret-Lutz writes:

> What I was trying to say in the previous message is that because
> the return type of gettext() and ngettext() ought to be `const
> char*' (even if it's not actually the case), people ought to
> treat it as so and write:
> 
>   const char *s = gettext("foobar");
> or
>   const char *s = ngettext("sing","plural",n);

Agreed,

> ~/tmp % gcc -Wwrite-strings -Wcast-qual -c f.c

-Wcast-qual is a stupid warning: it warns for valid uses of built-in
C language features. It's only use is for C to C++ conversions. So
let's avoid it. Just plain -Wall is much better.

$ gcc -Wall -c f.c

gives no warning.

$ gcc -Wall -Wwrite-strings -c f.c
f.c: In function `foo':
f.c:7: warning: initialization discards qualifiers from pointer target type

You want a warning for lines 7 and 8 but not for line 9 and 10? We get
it like this, even without -Wwrite-strings:

     1  # define gettext(Msgid) (const char *) (Msgid)
     2  # define ngettext(Msgid1, Msgid2, N) \
     3      ((N) == 1 ? (const char *) (Msgid1) : (const char *) (Msgid2))
     4
     5  void foo(void)
     6  {
     7          char* s1 = gettext("foobar");
     8          char* s2 = ngettext("sing","plural", 0);
     9          const char* c1 = gettext("foobar");
    10          const char* c2 = ngettext("sing","plural", 0);
    11
    12          (void)s1, (void)s2, (void)c1, (void)c2;
    13  }

> If, as suggested, you remove those casts, the annoying warning
> disappear and the usefull warnings remain:

I'll better leave the casts to 'const char *' in; they also provide
useful warnings for

     char *s;
     void foo(void)
     {
             char* s1 = gettext(s);
             char* s2 = ngettext(s,s, 0);
             const char* c1 = gettext(s);
             const char* c2 = ngettext(s,s, 0);
     }

Bruno