threads / patch / 7065

patch, 6 partsFix some "comparison is always true/false" warnings.

Subject: [PATCH 5/6] Fix some "comparison is always true/false" warnings.

## tl;dr

4 messages between Mar 3, 2007 and Mar 8, 2007. Diffs are folded; open one to read it.

replies: 3people: 2as markdown or json

Ramsay Jones· Mar 3, 2007, 18:28 UTC · lore

On Cygwin the wchar_t type is an unsigned short (16-bit) int. This results in the above warnings from the return statement in the wcwidth() function (in particular, the expressions involving constants with values larger than 0xffff). Simply replace the use of wchar_t with an unsigned int, typedef-ed as ucs_char_t.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
---
  utf8.c |   10 ++++++----
  1 files changed, 6 insertions(+), 4 deletions(-)

Show changes to utf8.c +6 −4

diff --git a/utf8.c b/utf8.c
index 7c80eec..211e100 100644
--- a/utf8.c
+++ b/utf8.c
@@ -3,13 +3,15 @@

  /* This code is originally from http://www.cl.cam.ac.uk/~mgk25/ucs/ */

+typedef unsigned int ucs_char_t;  /* assuming 32bit int */
+
  struct interval {
    int first;
    int last;
  };

  /* auxiliary function for binary search in interval table */
-static int bisearch(wchar_t ucs, const struct interval *table, int max) {
+static int bisearch(ucs_char_t ucs, const struct interval *table, int max) {
  	int min = 0;
  	int mid;

@@ -56,11 +58,11 @@ static int bisearch(wchar_t ucs, const struct interval *table, int max) {
   *      ISO 8859-1 and WGL4 characters, Unicode control characters,
   *      etc.) have a column width of 1.
   *
- * This implementation assumes that wchar_t characters are encoded
+ * This implementation assumes that ucs_char_t characters are encoded
   * in ISO 10646.
   */

-static int wcwidth(wchar_t ch)
+static int wcwidth(ucs_char_t ch)
  {
  	/*
  	 * Sorted list of non-overlapping intervals of non-spacing characters,
@@ -157,7 +159,7 @@ static int wcwidth(wchar_t ch)
  int utf8_width(const char **start)
  {
  	unsigned char *s = (unsigned char *)*start;
-	wchar_t ch;
+	ucs_char_t ch;

  	if (*s < 0x80) {
  		/* 0xxxxxxx */

-- 
1.5.0

Karl Hasselström· Mar 5, 2007, 07:45 UTC · re: Ramsay Jones · lore

Re: [PATCH 5/6] Fix some "comparison is always true/false" warnings.

On 2007-03-03 18:28:57 +0000, Ramsay Jones wrote:

> +typedef unsigned int ucs_char_t;  /* assuming 32bit int */

Umm ... wouldn't an uint32_t be a better fit here?

-- 
Karl Hasselström, kha@treskal.com
      www.treskal.com/kalle

Ramsay Jones· Mar 7, 2007, 19:05 UTC · re: Karl Hasselström · lore

Re: [PATCH 5/6] Fix some "comparison is always true/false" warnings.

Karl Hasselström wrote:

Show 6 quoted lines

> On 2007-03-03 18:28:57 +0000, Ramsay Jones wrote:
> 
>> +typedef unsigned int ucs_char_t;  /* assuming 32bit int */
> 
> Umm ... wouldn't an uint32_t be a better fit here?
>

Yes, but I did not want to add a dependency on a C99 header (i.e. <stdint.h>). I had a vague recollection that Linus had stated that git was probably broken if int wasn't 32 bits, so ...

This was before I realized that a recent change to git meant that git was already including C99 headers <inttypes.h> and, therefore indirectly, <stdint.h>.

So, if it is OK to depend on those headers, then an uin32_t may indeed be a better fit.

All the best,

Ramsay Jones

Karl Hasselström· Mar 8, 2007, 06:45 UTC · re: Ramsay Jones · lore

Re: [PATCH 5/6] Fix some "comparison is always true/false" warnings.

On 2007-03-07 19:05:49 +0000, Ramsay Jones wrote:

Show 11 quoted lines

> Karl Hasselström wrote:
>
> > Umm ... wouldn't an uint32_t be a better fit here?
>
> Yes, but I did not want to add a dependency on a C99 header (i.e.
> <stdint.h>). I had a vague recollection that Linus had stated that
> git was probably broken if int wasn't 32 bits, so ...
>
> This was before I realized that a recent change to git meant that
> git was already including C99 headers <inttypes.h> and, therefore
> indirectly, <stdint.h>.

Your approach is much more sophisticated than mine. :-) I just thought, "wow, this _screams_ for a uint32_t -- hmm, is it OK to use that?", and then did "git grep uint32_t" and got about a screenful of hits.

-- 
Karl Hasselström, kha@treskal.com
      www.treskal.com/kalle