Re: [PATCH] assert.h: allow gcc to detect assert(a = 1) errors

[Florian Weimer <fweimer at redhat dot com>]

On 11/26/2016 07:14 AM, Jim Meyering wrote:

> Here's a proposed ChangeLog entry:
>
> 2016-11-25  Jim Meyering  <meyering@fb.com>
>
>         Let gcc detect assert(a = 1) errors.
>         * assert/assert.h (assert): Rewrite assert's definition so that a
>         s/==/=/ typo, e.g., assert(errno = ENOENT) is not hidden from
>         gcc's -Wparentheses by assert-added parentheses.  The new
>         definition uses "if (expr) /* empty */; else __assert_fail...",
>         so gcc -Wall will now detect that type of error in an assert, too.
>         The __STRICT_ANSI__ disjunct is to avoid the warning that -Wpedantic
>         would otherwise issue for the use of ({...}).

Isn't this warning suppressed for system headers with -Wpedantic?

>         I would have preferred
>         to use __extension__ to mark that, but doing so would mistakenly
>         suppress warnings about any extension in the user-supplied "expr".
>         E.g., "assert ( ({1;}) )" must continue to evoke a warning.
>         https://bugzilla.redhat.com/1105335

The following is a bit silly.  glibc adheres to the GNU standards, which 
require that the ChangeLog only describes the change as such, not its 
rationale.  So the entry should probably look like this.

	Let GCC detect assert (a = 1) errors.
	* assert/assert.h (assert): Introduce __STRICT_ANSI__ variant.
	Use a GCC extension and an if statement for GNU compilers.

Thanks,
Florian