libguile/read.c warning

libguile/read.c warning

[Thien-Thi Nguyen]

../../GG/libguile/read.c: In function 'scm_read_expression':
../../GG/libguile/read.c:893: warning: 'charname' may be used uninitialized in this function

Re: libguile/read.c warning

[Ludovic Courtès]

Hi,

Thien-Thi Nguyen <ttn@gnuvola.org> writes:

> ../../GG/libguile/read.c: In function 'scm_read_expression':
> ../../GG/libguile/read.c:893: warning: 'charname' may be used uninitialized in this function

Which platform & compiler?

GNU/Linux builds at http://hydra.nixos.org/jobset/gnu/guile-master/all
are done with ‘-Werror’ on GCC 4.4.3 and they don’t have this problem.

Thanks,
Ludo’.

Re: libguile/read.c warning

[Thien-Thi Nguyen]

() ludo@gnu.org (Ludovic Courtès)
() Mon, 15 Feb 2010 10:26:49 +0100

   Which platform & compiler?

$ uname -a
Linux ambire 2.6.18-6-k7 #1 SMP Thu Nov 5 16:59:00 UTC 2009 i686 GNU/Linux
$ gcc --version
gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)

Inspection shows that (at least, as of commit 69f90b0b0):

  overflow = read_token (port, buffer, READER_CHAR_NAME_MAX_SIZE, &bytes_read);
  if (overflow)
    goto char_error;

  ...

 char_error:
  scm_i_input_error (FUNC_NAME, port, "unknown character name ~a",
		     scm_list_1 (charname));

if there is an overflow condition, `scm_i_input_error' is called with
`charname' not yet initialized.  This is in `scm_read_character',
which differs from the function indicated in the warning message.

I think the fix would be to do:
  if (overflow)
    scm_i_input_error (FUNC_NAME, port, "character overflow error", SCM_EOL);

or somesuch.

   GNU/Linux builds at http://hydra.nixos.org/jobset/gnu/guile-master/all
   are done with ‘-Werror’ on GCC 4.4.3 and they don’t have this problem.

Yeah, i'm still clinging onto personal happiness on Debian Etch.  It's
high time for a dist-upgrade, but then again, look at all the interesting
bugs we find on the trailing edge! :-D

thi