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[PATCH] revision: use C99 declaration of variable in for() loop

From
Junio C Hamano <gitster@pobox.com>
Date
Nov 15, 2021, 06:27 UTC
Message-ID
<xmqqpmr2j5lq.fsf_-_@gitster.g>
In-Reply-To
<xmqqilwulims.fsf@gitster.g>

There are certain C99 features that might be nice to use in our code base, but we've hesitated to do so in order to avoid breaking compatibility with older compilers. But we don't actually know if people are even using pre-C99 compilers these days.

One way to figure that out is to introduce a very small use of a feature, and see if anybody complains, and we've done so to probe the portability for a few features like "trailing comma in enum declaration", "designated initializer for struct", and "designated initializer for array". A few years ago, we tried to use a handy

    for (int i = 0; i < n; i++)
	use(i);

to introduce a new variable valid only in the loop, but found that some compilers we cared about didn't like it back then. Two years is a long-enough time, so let's try it agin.

If this patch can survive a few releases without complaint, then we can feel more confident that variable declaration in for() loop is supported by the compilers our user base use. And if we do get complaints, then we'll have gained some data and we can easily revert this patch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 revision.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/revision.c b/revision.c
index 9dff845bed..44492f2c02 100644
--- a/revision.c
+++ b/revision.c
@@ -43,10 +43,8 @@ static inline int want_ancestry(const struct rev_info *revs);
 
 void show_object_with_name(FILE *out, struct object *obj, const char *name)
 {
-	const char *p;
-
 	fprintf(out, "%s ", oid_to_hex(&obj->oid));
-	for (p = name; *p && *p != '\n'; p++)
+	for (const char *p = name; *p && *p != '\n'; p++)
 		fputc(*p, out);
 	fputc('\n', out);
 }
-- 
2.34.0-rc2-165-g9b3c04af29
Previous: Carlo ArenasNext: Martin Ågren
Message 11 of 22 in “MyFirstContribution.txt: fix undeclared variable i in sample code”
  1. MyFirstContribution.txt: fix undeclared variable i in sample codeSaksham Mittal, Nov 13, 2021
  2. Johannes AltmanningerNov 13, 2021
  3. Saksham MittalNov 13, 2021
  4. Junio C HamanoNov 14, 2021
  5. Is 'for (int i = [...]' bad for C STD compliance reasons? (was: [PATCH] MyFirstContribution.txt: fix undeclared variable i in sample code)Ævar Arnfjörð Bjarmason, Nov 14, 2021
  6. Junio C HamanoNov 14, 2021
  7. Ævar Arnfjörð BjarmasonNov 14, 2021
  8. Carlo ArenasNov 14, 2021
  9. brian m. carlsonNov 14, 2021
  10. Carlo ArenasNov 14, 2021
  11. revision: use C99 declaration of variable in for() loopJunio C Hamano, Nov 15, 2021
  12. Martin ÅgrenNov 15, 2021
  13. Junio C HamanoNov 16, 2021
  14. brian m. carlsonNov 15, 2021
  15. Phillip WoodNov 17, 2021
  16. Ævar Arnfjörð BjarmasonNov 17, 2021
  17. SZEDER GáborNov 17, 2021
  18. Junio C HamanoNov 18, 2021
  19. Phillip WoodDec 7, 2021
  20. Junio C HamanoDec 7, 2021
  21. Removing -Wdeclaration-after-statement (was: [PATCH] revision: use C99 declaration of variable in for() loop)Ævar Arnfjörð Bjarmason, Dec 8, 2021
  22. Junio C HamanoDec 8, 2021

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