Hi,
On FreeBSD 12.0/x86, the newest release m4-1.4.18 and the newest snapshot
from https://gitlab.com/gnu-m4/ci-distcheck/ both exhibit a "make check"
failure:
Checking ../../checks/189.eval
@ ../doc/m4.texi:6405: Origin of test
../../checks/189.eval: stdout mismatch
--- m4-tmp.17036/m4-xout 2020-05-03 02:14:13.289357000 +0200
+++ m4-tmp.17036/m4-out 2020-05-03 02:14:13.279345000 +0200
@@ -2,8 +2,8 @@
1
1
-overflow occurred
--2147483648
+
+2147483648
0
-2
-2
...
Failed checks were:
../../checks/189.eval:out
*** Error code 1
Simplified test case:
$ cat > in <<EOF
define(`max_int', eval(`0x7fffffff'))
define(`min_int', incr(max_int))
min_int
EOF
$ m4 < in
Expected output:
-2147483648
Actual output on FreeBSD:
2147483648
The bug occurs if and only if the source file builtin.c is compiled with
optimization -O2 or higher.
The attached patch (for the 'branch-1.4' branch) fixes the issue.
Bruno
>From aaa68d60ab6c84783cf050a9e43aa6f40c81e4df Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sun, 3 May 2020 03:00:46 +0200
Subject: [PATCH] Work around a compiler optimization bug on FreeBSD 12.0.
* src/builtin.c (ntoa): Declare value parameter as 'volatile'.
---
src/builtin.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/builtin.c b/src/builtin.c
index 4eaccc6..988cc93 100644
--- a/src/builtin.c
+++ b/src/builtin.c
@@ -1,6 +1,6 @@
/* GNU m4 -- A simple macro processor
- Copyright (C) 1989-1994, 2000, 2004, 2006-2014, 2016-2017 Free
+ Copyright (C) 1989-1994, 2000, 2004, 2006-2014, 2016-2017, 2020 Free
Software Foundation, Inc.
This file is part of GNU M4.
@@ -449,8 +449,9 @@ numeric_arg (token_data *macro, const char *arg, int *valuep)
/* Digits for number to ASCII conversions. */
static char const digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
+/* The 'volatile' neutralizes a clang 6.0.1 optimization bug. */
const char *
-ntoa (int32_t value, int radix)
+ntoa (int32_t volatile value, int radix)
{
bool negative;
uint32_t uvalue;
--
2.7.4
