Build error __warn_memset_zero_len

[Marco Becker]

I got the following error wehn build the source code with gcc option -O3:

gcc -c -pipe  -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Werror -g -O3 -I src/core -I src/event -I src/event/modules -I src/os/unix -I objs -I src/http -I src/http/modules \
		-o objs/src/http/modules/ngx_http_autoindex_module.o \
		src/http/modules/ngx_http_autoindex_module.c
In file included from /usr/include/string.h:642:0,
                 from src/os/unix/ngx_linux_config.h:26,
                 from src/core/ngx_config.h:26,
                 from src/http/modules/ngx_http_autoindex_module.c:8:
In Funktion »memset«,
    eingefügt von »ngx_http_autoindex_handler« bei src/http/modules/ngx_http_autoindex_module.c:492:13:
/usr/include/x86_64-linux-gnu/bits/string3.h:82:30: Fehler: Aufruf von »__warn_memset_zero_len« mit Attributwarnung deklariert: memset used with constant zero length parameter; this could be due to transposed parameters [-Werror]
cc1: Alle Warnungen werden als Fehler behandelt
make[1]: *** [objs/src/http/modules/ngx_http_autoindex_module.o] Fehler 1
make[1]: Verlasse Verzeichnis '/root/nginx-1.2.6'
make: *** [build] Fehler 2

The ./configure options as follows:

./configure --sbin-path=/opt/nginx --conf-path=/etc/nginx/nginx.conf --pid-path=/etc/nginx/nginx.pid --prefix=/opt/nginx --with-cc-opt="-O3"

[Maxim Dounin]

This seems to be a warning incorrectly generated by Linux headers when high optimization levels are used (see ​1, ​2). As a workaround you may use

./configure --with-cc-opt="-O3 -Wno-error"

to compile with -O3 on Linux.

[johnleach.co.uk]

Fix for compilation warning

[johnleach.co.uk]

This patch works around the compile warning without much effort, and it also means we don't have to disable the checking (which is generally useful, and is the default for recent package builds too).

There is no other occurrence of a false positive like this in the codebase btw - this is the only thing I've found that needed a tweak. Any chance it could be merged?

[johnleach.co.uk]

Fix for compilation warning

[maxim]

Maxim, please take a look at the enclosed patch and decide what to do with it.

[Maxim Dounin]

In 5070/nginx:

Fixed false memset warning on Linux with -O3 (ticket #275).

Prodded by John Leach.

[Maxim Dounin]

As this is indeed the only warning generated for the code I've committed the patch, slightly modified to better match style and surrounding code. Thanks.

[Maxim Dounin]

In 5151/nginx:

Merge of r5070: fixed false memset warning on Linux.

Fixed false memset warning on Linux with -O3 (ticket #275).

Prodded by John Leach.