bug#8229: possibly uninitialized variable in load_charset

[Paul Eggert]

Severity: minor

I found this problem by compiling Emacs with GCC's -Wuninitialized flag.

The following code in the Emacs trunk src/charset.c's load_charset
function is suspicious, because as written it appears that it might be
using an uninitialized variable:

  if (CHARSET_METHOD (charset) == CHARSET_METHOD_MAP)
    map = CHARSET_MAP (charset);
  else if (CHARSET_UNIFIED_P (charset))
    map = CHARSET_UNIFY_MAP (charset);
  if (STRINGP (map))
    ...

The last if-test uses "map", but it's not clear from the previous
tests that "map" must be initialized.

I'm filing a bug report so that someone who is more expert in this
code can take a look at it.  In the meantime, I plan to work around
the problem by replacing:

  else if (CHARSET_UNIFIED_P (charset))
    map = CHARSET_UNIFY_MAP (charset);

with:

  else
    {
      if (! CHARSET_UNIFIED_P (charset))
        abort ();
      map = CHARSET_UNIFY_MAP (charset);
    }

I'm CC'ing this to Kenichi Handa, who committed the code in question.