[PATCH 3/5] CodingGuidelines: allow declaring variables in for loops

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Since 44ba10d6712 (revision: use C99 declaration of variable in for()
loop, 2021-11-14) released with v2.35.0 we've had a variable declared
with in a for loop.

Since then we've had inadvertent follow-ups to that with at least
cb2607759e2 (merge-ort: store more specific conflict information,
2022-06-18) released with v2.38.0.

As November 2022 is within the window of this upcoming release let's
update the guideline to allow this, and revert the recent
6983f4e3b20 (test-parse-options.c: don't use for loop initial
declaration, 2022-09-05).

It's better to update the guidelines than to have back & forth churn
like that, we clearly don't have portability issues related to this
syntax.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/CodingGuidelines | 10 ++--------
 revision.c                     |  7 -------
 t/helper/test-parse-options.c  |  3 +--
 3 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index 8afda28cfce..f9affc4050a 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -232,18 +232,12 @@ For C programs:
    . since early 2021 with 765dc168882, we have been using variadic
      macros, mostly for printf-like trace and debug macros.
 
-   These used to be forbidden, but we have not heard any breakage
-   report, and they are assumed to be safe.
+   . since late 2021 with 44ba10d6, we have had variables declared in
+     the for loop "for (int i = 0; i < 10; i++)".
 
  - Variables have to be declared at the beginning of the block, before
    the first statement (i.e. -Wdeclaration-after-statement).
 
- - Declaring a variable in the for loop "for (int i = 0; i < 10; i++)"
-   is still not allowed in this codebase.  We are in the process of
-   allowing it by waiting to see that 44ba10d6 (revision: use C99
-   declaration of variable in for() loop, 2021-11-14) does not get
-   complaints.  Let's revisit this around November 2022.
-
  - NULL pointers shall be written as NULL, not as 0.
 
  - When declaring pointers, the star sides with the variable
diff --git a/revision.c b/revision.c
index 36e31942cee..8f2623b3b5a 100644
--- a/revision.c
+++ b/revision.c
@@ -47,13 +47,6 @@ static inline int want_ancestry(const struct rev_info *revs);
 void show_object_with_name(FILE *out, struct object *obj, const char *name)
 {
 	fprintf(out, "%s ", oid_to_hex(&obj->oid));
-	/*
-	 * This "for (const char *p = ..." is made as a first step towards
-	 * making use of such declarations elsewhere in our codebase.  If
-	 * it causes compilation problems on your platform, please report
-	 * it to the Git mailing list at git@vger.kernel.org. In the meantime,
-	 * adding -std=gnu99 to CFLAGS may help if you are with older GCC.
-	 */
 	for (const char *p = name; *p && *p != '\n'; p++)
 		fputc(*p, out);
 	fputc('\n', out);
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index 506835521a4..f8a62d892d9 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -195,8 +195,7 @@ int cmd__parse_options(int argc, const char **argv)
 
 static void print_args(int argc, const char **argv)
 {
-	int i;
-	for (i = 0; i < argc; i++)
+	for (int i = 0; i < argc; i++)
 		printf("arg %02d: %s\n", i, argv[i]);
 }
 
-- 
2.38.0.971.ge79ff6d20e7