Re: C/C++ Compiler Invalidly Turning Warnings into Errors?

[Stephen Morris]

On 01/15/2015 11:38 PM, Sam Varshavchik wrote:
Stephen Morris writes:
I have a driver for a wifi usb device that I need to compile because 
there are no drivers in the kernel, which has been obtained from the 
vendor of the device. When I attempt to compile the code the compile 
fails on the grounds that some warnings are being translated into 
errors. From my perspective these errors should not be happening 
because, when a debugging module wants to time stamp the build, that 
is not an error and is perfectly acceptable. How do I get the 
compiler to stop producing these errors. The messages I get are 
listed below.

The makefile that's used to build this module explicitly specifies a 
compiler flag that makes this diagnostic an error. You can see it 
referenced in the error message, -Werror=date-time

So the answer to your question is very simple: it happens because 
that's what it does. I'm sure there's a way to override this flag. 
Look at the makefile, figure out where it specifies this flag, and 
take it out, if that's what you want to do. It might be possible to 
pass some flags on the command line to override it; can't really say 
without looking at the makefile.

If this driver is supposedly obtained from the vendor, and I'd think 
it's highly unlikely that Fedora manually patches the upstream kernel 
to add this flag, so the conclusion to draw from this is that the 
vendor has never tested their module with a kernel that's more recent 
than whatever is the first version of the kernel whose makefile was 
set up that way. I'd say that this compiler error is the least of your 
problems.
Thanks Sam, I've found the Makefile that does the compiling and it 
doesn't supply the parameter, -Werror specification is listed in there 
but is commented out, so if it is not specified in the kernel source 
then it is coming from one of the includes being used. I may have to 
compile the kernel manually myself as well anyway, as the makefile seems 
to be specifying dependencies on kernel config specifications that don't 
appear to be active in the pre-compiled kernels I am using.

Authentication requested [root] for make driver:
make ARCH=x86_64 CROSS_COMPILE= -C 
/lib/modules/3.17.8-300.fc21.x86_64/build 
M=/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411 
modules
make[1]: Entering directory '/usr/src/kernels/3.17.8-300.fc21.x86_64'
  CC [M] 
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_cmd.o
  CC [M] 
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_security.o
  CC [M] 
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.o
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c: 
In function ‘dump_drv_version’:
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:64: 
error: macro "__DATE__" might prevent reproducible builds 
[-Werror=date-time]
  DBG_871X_SEL_NL(sel, "build time: %s %s\n", __DATE__, __TIME__);
^
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:1: 
error: macro "__TIME__" might prevent reproducible builds 
[-Werror=date-time]
  DBG_871X_SEL_NL(sel, "build time: %s %s\n", __DATE__, __TIME__);
 ^
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:1: 
error: macro "__DATE__" might prevent reproducible builds 
[-Werror=date-time]
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:1: 
error: macro "__TIME__" might prevent reproducible builds 
[-Werror=date-time]
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:1: 
error: macro "__DATE__" might prevent reproducible builds 
[-Werror=date-time]
/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.c:66:1: 
error: macro "__TIME__" might prevent reproducible builds 
[-Werror=date-time]
cc1: some warnings being treated as errors
scripts/Makefile.build:257: recipe for target 
'/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.o' 
failed
make[2]: *** 
[/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411/core/rtw_debug.o] 
Error 1
Makefile:1377: recipe for target 
'_module_/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411' 
failed
make[1]: *** 
[_module_/usr/local/downloads/dlink/RTL8812AU_linux_v4.3.2_11100.20140411/driver/rtl8812AU_linux_v4.3.2_11100.20140411] 
Error 2
make[1]: Leaving directory '/usr/src/kernels/3.17.8-300.fc21.x86_64'
Makefile:1350: recipe for target 'modules' failed
make: *** [modules] Error 2
##################################################
Compile make driver error: 2
Please check error Mesg
##################################################




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