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warning: unsequenced modification and access to 'sa_avail'
From: |
Jeffrey Walton |
Subject: |
warning: unsequenced modification and access to 'sa_avail' |
Date: |
Sat, 27 Mar 2021 12:05:00 -0400 |
Hi Everyone,
I'm building Emacs 27.2 on the Apple M1 machine. I think the compiler
is complaining about undefined behavior:
sa_avail -= (size), alloca (size)
I think it is equivalent to something like this:
data[i] = data[i++];
/usr/bin/clang -c -I/usr/local/include -DNDEBUG -Demacs -I. -I.
-I../lib -I../lib -I/usr/local/include/libxml2
-I/usr/local/include -MMD -MF deps/doc.d -MP
-I/usr/local/include -I/usr/local/include/p11-kit-1 -Wno-switch
-Wno-pointer-sign -Wno-string-plus-int -Wno-unknown-attributes
-Wno-initializer-overrides -Wno-tautological-compare
-Wno-tautological-constant-out-of-range-compare -g2 -O2 -fno-common
-arch arm64 -fPIC -pthread doc.c
/usr/bin/clang -c -I/usr/local/include -DNDEBUG -Demacs -I. -I.
-I../lib -I../lib -I/usr/local/include/libxml2
-I/usr/local/include -MMD -MF deps/editfns.d -MP
-I/usr/local/include -I/usr/local/include/p11-kit-1 -Wno-switch
-Wno-pointer-sign -Wno-string-plus-int -Wno-unknown-attributes
-Wno-initializer-overrides -Wno-tautological-compare
-Wno-tautological-constant-out-of-range-compare -g2 -O2 -fno-common
-arch arm64 -fPIC -pthread editfns.c
editfns.c:2063:18: warning: unsequenced modification and access to 'sa_avail'
[-Wunsequenced]
.deletions = SAFE_ALLOCA (del_bytes),
^
./lisp.h:4817:9: note: expanded from macro 'SAFE_ALLOCA'
? AVAIL_ALLOCA (size) \
^
./lisp.h:4812:38: note: expanded from macro 'AVAIL_ALLOCA'
#define AVAIL_ALLOCA(size) (sa_avail -= (size), alloca (size))
^
Jeff
- warning: unsequenced modification and access to 'sa_avail',
Jeffrey Walton <=