[bug #65537] Werrors from intprops-internal.h with gcc 8.3.0

[Paul Eggert]

Follow-up Comment #6, bug #65537 (group make):

[comment #4 comment #4:]
> In file included from lib/intprops.h:21,
>                  from src/arscan.c:379:
> src/arscan.c: In function ‘parse_int’:
> lib/intprops-internal.h:387:35: error: comparison of integer expressions of
different signedness: ‘int’ and ‘uintmax_t’ {aka ‘long unsigned
int’} [-Werror=sign-compare]
>           : 0 < (a) && -1 - (tmin) < (a) - 1) \
>                                    ^

This is a false alarm from old versions of GCC that suffer from GCC bug 91450.
Please try the following patch to intprops-internal.h and let me know whether
it works (I no longer use those old GCC versions). The patch should works
without your having to fiddle with MAKE_CFLAGS. If the patch works, I can
install it into Gnulib.

>From cf67e37e3a9b217c83fdcae5ce883009d94b7ae8 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 29 Mar 2024 14:34:27 -0700
Subject: [PATCH] intprops: pacify GCC < 10 -Wsign-compare

Problem reported by Martin Dorey in:
https://savannah.gnu.org/bugs/index.php?65537
* lib/intprops-internal.h (_GL_INT_MULTIPLY_WRAPV):
When working around GCC bug 91450, pacify -Wsign-compare by
casting 0 to the result type.
---
 ChangeLog               | 9 +++++++++
 lib/intprops-internal.h | 4 +++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 931322915b..f967275871 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2024-03-29  Paul Eggert  <eggert@cs.ucla.edu>
+
+       intprops: pacify GCC < 10 -Wsign-compare
+       Problem reported by Martin Dorey in:
+       https://savannah.gnu.org/bugs/index.php?65537
+       * lib/intprops-internal.h (_GL_INT_MULTIPLY_WRAPV):
+       When working around GCC bug 91450, pacify -Wsign-compare by
+       casting 0 to the result type.
+
 2024-03-29  Collin Funk  <collin.funk1@gmail.com>
 
        gnulib-tool.py: Display specified modules in bold.
diff --git a/lib/intprops-internal.h b/lib/intprops-internal.h
index c8a87d2bb2..b5ba8d7cbd 100644
--- a/lib/intprops-internal.h
+++ b/lib/intprops-internal.h
@@ -169,7 +169,9 @@
    /* Work around GCC bug 91450.  */
 #  define _GL_INT_MULTIPLY_WRAPV(a, b, r) \
     ((!_GL_SIGNED_TYPE_OR_EXPR (*(r)) && _GL_EXPR_SIGNED (a) &&
_GL_EXPR_SIGNED (b) \
-      && _GL_INT_MULTIPLY_RANGE_OVERFLOW (a, b, 0, (__typeof__ (*(r))) -1))
\
+      && _GL_INT_MULTIPLY_RANGE_OVERFLOW (a, b, \
+                                          (__typeof__ (*(r))) 0, \
+                                          (__typeof__ (*(r))) -1)) \
      ? ((void) __builtin_mul_overflow (a, b, r), 1) \
      : __builtin_mul_overflow (a, b, r))
 # endif
-- 
2.44.0





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