Avoid unnecessary "if-before-free" tests.

This change removes all obvious useless if-before-free tests.
E.g., it replaces code like this:

        if (some_expression)
                free (some_expression);

with the now-equivalent:

        free (some_expression);

It is equivalent not just because POSIX has required free(NULL)
to work for a long time, but simply because it has worked for
so long that no reasonable porting target fails the test.
Here's some evidence from nearly 1.5 years ago:

    http://www.winehq.org/pipermail/wine-patches/2006-October/031544.html

FYI, the change below was prepared by running the following:

  git ls-files -z | xargs -0 \
  perl -0x3b -pi -e \
    's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+(free\s*\(\s*\1\s*\))/$2/s'

Note however, that it doesn't handle brace-enclosed blocks like
"if (x) { free (x); }".  But that's ok, since there were none like
that in git sources.

Beware: if you do use the above snippet, note that it can
produce syntactically invalid C code.  That happens when the
affected "if"-statement has a matching "else".
E.g., it would transform this

  if (x)
    free (x);
  else
    foo ();

into this:

  free (x);
  else
    foo ();

There were none of those here, either.

If you're interested in automating detection of the useless
tests, you might like the useless-if-before-free script in gnulib:
[it *does* detect brace-enclosed free statements, and has a --name=S
 option to make it detect free-like functions with different names]

  http://git.sv.gnu.org/gitweb/?p=gnulib.git;a=blob;f=build-aux/useless-if-before-free

Addendum:
  Remove one more (in imap-send.c), spotted by Jean-Luc Herren <jlh@gmx.ch>.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/diff.c b/diff.c
index 699b21f4e3..f08e663b86 100644
--- a/diff.c
+++ b/diff.c
@@ -118,8 +118,7 @@ static int parse_funcname_pattern(const char *var, const char *ep, const char *v
 		pp->next = funcname_pattern_list;
 		funcname_pattern_list = pp;
 	}
-	if (pp->pattern)
-		free(pp->pattern);
+	free(pp->pattern);
 	pp->pattern = xstrdup(value);
 	return 0;
 }
@@ -492,10 +491,8 @@ static void free_diff_words_data(struct emit_callback *ecbdata)
 				ecbdata->diff_words->plus.text.size)
 			diff_words_show(ecbdata->diff_words);
 
-		if (ecbdata->diff_words->minus.text.ptr)
-			free (ecbdata->diff_words->minus.text.ptr);
-		if (ecbdata->diff_words->plus.text.ptr)
-			free (ecbdata->diff_words->plus.text.ptr);
+		free (ecbdata->diff_words->minus.text.ptr);
+		free (ecbdata->diff_words->plus.text.ptr);
 		free(ecbdata->diff_words);
 		ecbdata->diff_words = NULL;
 	}