Re: Cast "const char *" pointers to "char *" to avoid compiler warnings.

On 01/10/18 22:33, Christophe Lyon wrote:
> Hi,
> 
> GCC complains that some assignments loose the const-ness of several
> data. This small patch adds explicit (char *) casts, but I'm not
> familiar enough with what newlib does with these to be sure that they
> are not modified. Maybe the proper fix would be to declare the
> destinations as "const"?
> 
> Christophe
> 
> 
> newlib-4.txt
> 
> 
> commit 349a08c43cd4baf0d93f28ea8ca7351bf9606d50
> Author: Christophe Lyon <[email protected]>
> Date:   Mon Oct 1 18:53:37 2018 +0000
> 
>     Cast "const char *" pointers to "char *" to avoid compiler warnings.
>     
>     2018-10-01  Christophe Lyon  <[email protected]>
>     
>     	* newlib/libc/ctype/ctype_.c (__set_ctype): Cast "_ctype_" to "char *".
>     	* newlib/libc/ctype/jp2uc.c (_jp2uc_l, _uc2jp_l): Cast output of
>     	"__locale_charset()" and "__current_locale_charset()" to "char *".
>     	* newlib/libc/locale/locale.c (__loadlocale): Cast "new_locale" to
>     	"char *".
> 
> diff --git a/newlib/libc/ctype/ctype_.c b/newlib/libc/ctype/ctype_.c
> index 28727e8..851fc06 100644
> --- a/newlib/libc/ctype/ctype_.c
> +++ b/newlib/libc/ctype/ctype_.c
> @@ -176,7 +176,7 @@ __set_ctype (struct __locale_t *loc, const char *charset)
>  #  if defined(ALLOW_NEGATIVE_CTYPE_INDEX)
>       ctype_ptr = _ctype_b;
>  #  else
> -     ctype_ptr = _ctype_;
> +     ctype_ptr = (char *) _ctype_;
>  #  endif
>      }
>  #  if defined(ALLOW_NEGATIVE_CTYPE_INDEX)
> diff --git a/newlib/libc/ctype/jp2uc.c b/newlib/libc/ctype/jp2uc.c
> index b89b5ea..00272eb 100644
> --- a/newlib/libc/ctype/jp2uc.c
> +++ b/newlib/libc/ctype/jp2uc.c
> @@ -166,7 +166,7 @@ __uc2jp (wint_t c, int type)
>  wint_t
>  _jp2uc_l (wint_t c, struct __locale_t * l)
>  {
> -  char * cs = l ? __locale_charset(l) : __current_locale_charset();
> +  char * cs = l ? (char *) __locale_charset(l) : (char *) __current_locale_charset();

Why not change cs to const char *?  It's only used to call strcmp.

Probably most other casts should be similarly considered.

Generally, this patch feels wrong, IMO.

R.

>    if (0 == strcmp (cs, "JIS"))
>      c = __jp2uc (c, JP_JIS);
>    else if (0 == strcmp (cs, "SJIS"))
> @@ -186,7 +186,7 @@ _jp2uc (wint_t c)
>  wint_t
>  _uc2jp_l (wint_t c, struct __locale_t * l)
>  {
> -  char * cs = l ? __locale_charset(l) : __current_locale_charset();
> +  char * cs = l ? (char *) __locale_charset(l) : (char *) __current_locale_charset();
>    if (0 == strcmp (cs, "JIS"))
>      c = __uc2jp (c, JP_JIS);
>    else if (0 == strcmp (cs, "SJIS"))
> diff --git a/newlib/libc/locale/locale.c b/newlib/libc/locale/locale.c
> index 791a775..79da35f 100644
> --- a/newlib/libc/locale/locale.c
> +++ b/newlib/libc/locale/locale.c
> @@ -515,7 +515,7 @@ restart:
>      }
>  # define FAIL	goto restart
>  #else
> -  locale = new_locale;
> +  locale = (char *) new_locale;
>  # define FAIL	return NULL
>  #endif
>  
>