From 5172494c09718ffcb7ef1f19b3b211e3bce8781a Mon Sep 17 00:00:00 2001
From: Vincent Lefevre <vincent@vinc17.net>
Date: Tue, 10 Jan 2023 17:05:17 +0100
Subject: [PATCH] [tests/tsprintf.c] Modified a buggy test of the thousands
 separator.

The test

  check_vsprintf ("+01,234,567  :", "%0+ -'13.10Pd:", (mpfr_prec_t) 1234567);

is based on the output from glibc up to 2.36, which is incorrect:

  https://sourceware.org/bugzilla/show_bug.cgi?id=23432

The GNU C Library has apparently been partially fixed in its Git
repository for the future 2.37, since a tsprintf failure has been
reported (this is a bug in this test, not in the MPFR library):

  https://sympa.inria.fr/sympa/arc/mpfr/2023-01/msg00001.html

So, modified the test to avoid the particular case of leading zeros
due to the precision field larger than the number of digits. This
case has already been tested without the thousands separator (where
there are no issues with the C libraries), so that we do not miss
much testing. Added a comment explaining the issue and a possible
solution for future testing of this particular case (if need be).
---
 tests/tsprintf.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/tsprintf.c b/tests/tsprintf.c
index c68b2ba71..c0182503b 100644
--- a/tests/tsprintf.c
+++ b/tests/tsprintf.c
@@ -1719,7 +1719,17 @@ test_locale (void)
   check_sprintf ("000000001,000", "%'013.4Rg", x);
 
 #ifdef PRINTF_GROUPFLAG
-  check_vsprintf ("+01,234,567  :", "%0+ -'13.10Pd:", (mpfr_prec_t) 1234567);
+  /* Do not test the thousands separator with a precision field larger
+     than the number of digits (thus needing leading zeros), such as
+     "%0+ -'13.10Pd:" (used up to MPFR 4.2.0), since the GNU libc is
+     buggy: https://sourceware.org/bugzilla/show_bug.cgi?id=23432
+     We don't know about the other implementations.
+     If we wanted to check that and avoid a failure of the test because of
+     a buggy C library (while MPFR would be consistent with the C library),
+     we could compare the MPFR output with both the correct output and the
+     output from the C library (possibly buggy). But to do that in a clean
+     way, this would require a change in the check_vsprintf() call. */
+  check_vsprintf ("+1,234,567   :", "%0+ -'13Pd:", (mpfr_prec_t) 1234567);
 #endif
 
   mpfr_clear (x);
-- 
GitLab

