Re: [PATCH v7] C, ObjC: Add -Wunterminated-string-initialization

[Sandra Loosemore <sloosemore@baylibre.com>]

On 3/5/24 13:33, Alejandro Colomar wrote:
> Warn about the following:
> 
>      char  s[3] = "foo";
> 
> Initializing a char array with a string literal of the same length as
> the size of the array is usually a mistake.  Rarely is the case where
> one wants to create a non-terminated character sequence from a string
> literal.
> 
> In some cases, for writing faster code, one may want to use arrays
> instead of pointers, since that removes the need for storing an array of
> pointers apart from the strings themselves.
> 
>      char  *log_levels[]   = { "info", "warning", "err" };
> vs.
>      char  log_levels[][7] = { "info", "warning", "err" };
> 
> This forces the programmer to specify a size, which might change if a
> new entry is later added.  Having no way to enforce null termination is
> very dangerous, however, so it is useful to have a warning for this, so
> that the compiler can make sure that the programmer didn't make any
> mistakes.  This warning catches the bug above, so that the programmer
> will be able to fix it and write:
> 
>      char  log_levels[][8] = { "info", "warning", "err" };
> 
> This warning already existed as part of -Wc++-compat, but this patch
> allows enabling it separately.  It is also included in -Wextra, since
> it may not always be desired (when unterminated character sequences are
> wanted), but it's likely to be desired in most cases.
> 
> Since Wc++-compat now includes this warning, the test has to be modified
> to expect the text of the new warning too, in <gcc.dg/Wcxx-compat-14.c>.

The documentation parts of the patch are OK.

-Sandra