|
From: | Philippe Mathieu-Daudé |
Subject: | Re: [Qemu-devel] [PATCH] kvm: workaround build break on gcc-7.1.1 / fedora26 |
Date: | Thu, 3 Aug 2017 11:07:13 -0300 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 |
On 08/03/2017 10:55 AM, Eric Blake wrote:
On 08/03/2017 08:34 AM, Philippe Mathieu-Daudé wrote:Hi Greg, On 08/02/2017 11:47 AM, Greg Kurz wrote:Building QEMU on fedora26 with the latest gcc package fails: CC ppc64-softmmu/target/ppc/kvm.o In file included from include/sysemu/hw_accel.h:16:0, from target/ppc/kvm.c:31: target/ppc/kvm.c: In function ‘kvmppc_booke_watchdog_enable’: include/sysemu/kvm.h:449:35: error: ‘args_tmp[i]’ may be used uninitializedThis sizeof() use looks unnatural to me. I wonder why not use size_t, since this is about sizeof()/ARRAY_SIZE(). The problem seems to come from the commit this cast was introduced (61c7bbd236): target-ppc/kvm.c:1302:21: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits] So I'd rather suggest this code, which looks more natural to read to me: if (ARRAY_SIZE(args_tmp)) { for (i = 0; i < ARRAY_SIZE(args_tmp) && ...
Oops I forgot to suggest size_t i.
For that matter, the existing code is doing: int i; i < (int)ARRAY_SIZE(args_tmp) but wouldn't that be better as: size_t i; i < ARRAY_SIZE(args_temp) I guess we have both the old compilers (per commit 61c7bbd2) and the new to worry about; although I was unable to reproduce it on Fedora 26 on x86_64 (is this an architecture-dependent compiler bug?)
Ok so let's stop losing time about compiler incoherent warnings, using -Wno-type-limits for GCC < 5... So we can keep a sane/understandable codebase, using size_t and no (int) cast.
Phil.
[Prev in Thread] | Current Thread | [Next in Thread] |