Re: [PATCH 2/3] gdb: make macro_expand_next return a gdb::unique_xmalloc_ptr<char>

[Tom Tromey <tom@tromey.com>]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> I removed the ATTRIBUTE_UNUSED_RESULT on macro_buffer::release, I don't
Simon> really understand why it's there.  I don't see how this method could be
Simon> called without using the result, that would be an obvious memory leak.
Simon> The commit that introduced it (4e4a8b932b7 "Add ATTRIBUTE_UNUSED_RESULT
Simon> to macro_buffer") doesn't give any details.

Sorry about the lack of details!

Simon> -  /* Release the text of the buffer to the caller, which is now
Simon> -     responsible for freeing it.  */
Simon> -  ATTRIBUTE_UNUSED_RESULT char *release ()
Simon> +  /* Release the text of the buffer to the caller.  */
Simon> +  gdb::unique_xmalloc_ptr<char> release ()

In the old code, the caller had to remember to free the resulting char*.
ATTRIBUTE_UNUSED_RESULT meant that one couldn't write "x.release();"
without at least doing something with the result.

There was at least one case of this happening, though I didn't read
through the thread to find out exactly where it was:

https://sourceware.org/pipermail/gdb-patches/2019-February/155835.html

Using a unique pointer eliminates this common source of bugs, so I think
removing the attribute makes sense.

This patch looks fine to me.

Tom