How can I disable fail on warning when using GCC and Make?

Question

I'm trying to build GCC for use with an AVR microcontroller and avr-ada, and I've hit a roadblock caused by my regular compiler being too picky about the version I needed for the AVR. I get the following warning, which in turn causes GCC or Make to report an error:

gcc -c -g -O2 -gnatpg -gnata -nostdinc -I- -I. -Iada
  -I../../gcc/ada ../../gcc/ada/exp_ch5.adb -o ada/exp_ch5.o
exp_ch5.adb:177:16: warning: function "Has_Address_Clause" is not referenced
make[2]: *** [ada/exp_ch5.o] Error 1
make[1]: *** [all-gcc] Error 2
make: *** [all] Error 2

Is there a way to instruct GCC or Make to not fail on warnings?

I don't think any of the debug options result in treating warnings as errors (at least not that I could find), is that the full output? — Tim Post, Mar 10 '10 at 03:15
Normally (when not using `-gnatg` to apply all the checks required for a compiler build), GNAT (Ada in GCC) uses `-gnatwe` to treat warnings as errors, and `-gnatwn` to cancel that — Simon Wright, Oct 23 '22 at 15:58

score 52 · Answer 1 · answered Mar 10 '10 at 03:13

52

Try make -k instead of just make. That will 'continue' rather than stop.

answered Mar 10 '10 at 03:13

Dirk Eddelbuettel

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score 15 · Answer 2 · edited Oct 23 '22 at 01:21

15

As an alternative to diving into the build system, try setting -Wno-error in CFLAGS, which you should be able to do through the environment (or at configure time, if using the GNU build system).

edited Oct 23 '22 at 01:21

Peter Mortensen

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answered Mar 10 '10 at 05:51

Jack

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Simon Wright · Accepted Answer · 2017-01-18T21:10:23.707

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The trigger here is the -gnatpg (actually, the -gnatg): this is the "GNAT implementation mode (used for compiling GNAT units)". -gnatp means "suppress all checks".

I'm not sure of the full effect of -gnatg, though it certainly causes warnings to be treated as errors -- like -Werror -- at any rate while building the compiler itself; I think I remember seeing non-fatal warnings while building the RTS.

One possibility would be to compile just exp_ch5.adb by hand without -gnatg; the command you list was issued at gcc/, so

$ cd gcc
$ gcc -c -g -O2 -gnatp -gnata -nostdinc -I- -I. -Iada -I../../gcc/ada \
  ../../gcc/ada/exp_ch5.adb -o ada/exp_ch5.o

Then back up one level, and 'make' again.

This is a cross-compiler, so you won't (I hope!) need to repeat this for all three stages of a full build.

edited Jan 18 '17 at 21:10

answered Mar 10 '10 at 21:10

Simon Wright

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Thank you, your solution allowed me to get past the above error. I have more warnings from the Ada compiler, but I'll tread along now! – Dr. Watson Mar 11 '10 at 12:51
What is "RTS"? [Runtime system](https://en.wikipedia.org/wiki/Runtime_system)? – Peter Mortensen Oct 23 '22 at 01:27
@PeterMortensen, yes. – Simon Wright Oct 23 '22 at 15:54

score 5 · Answer 4 · edited Oct 23 '22 at 01:20

5

It seems the -Werror flag is set in the Makefile. Maybe you can look for the CFLAGS options in the Makefile and remove the -Werror flag. The Werror flag will make all warnings into errors.

edited Oct 23 '22 at 01:20

Peter Mortensen

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answered Mar 10 '10 at 03:20

ZelluX

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ezpz · Answer 5 · 2010-03-10T15:08:32.247

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In general, it is not a good idea to ignore warnings from your compiler. However, if this is a portion of a larger make process there is likely a -Werror flag inserted earlier in the sequence. Start by looking for that.

After looking around, there seems to be a wealth of flags to control warnings while compiling Ada code. For instance, -gnatwF will Suppress warnings on unreferenced formals according to this guide. Possibly the switch you require can be found in the list provided there.

edited Mar 10 '10 at 15:08

answered Mar 10 '10 at 03:22

ezpz

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Yeah, nothing in what he pasted would have resulted in -Werror being turned on. It had to be prior to the excerpt. – Tim Post Mar 10 '10 at 03:49
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I know its not a good idea, and I tried building an older version of gcc/gnat (gcc-4.3.2) just so that I could build the AVR gcc/gnat (also gcc-4.3.2), but I was running into the exact same problem there too. After talking with the project owner, he told me my system Ada compiler (gcc-4.3.4) "smells too new" for the code base, and my options were to hack the source code or try to override the fail or warning. – Dr. Watson Mar 10 '10 at 14:01
Well, I remember dealing with Ada for a brief time and, for me, the approach would have to be augmenting the build. As I recall Ada is right finicky about things. – ezpz Mar 10 '10 at 14:52
Again, I agree with what you are saying. I'll try some of the options you listed as well as others in this thread when I get home today, but I'm learning towards just using the Windows version since I can easily get a binary and get to work. – Dr. Watson Mar 10 '10 at 15:19

score 1 · Answer 6 · answered May 09 '13 at 16:49

1

In gcc configure you can add --disable-werror.

Though it's advisable to seek out a proper patch first.

answered May 09 '13 at 16:49

Bob Blogge

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It does not work for me: # gcc --disable-werror -Werror -Wall foo.c cc1: error: unknown pass werror specified in -fdisable – Breno Leitão Sep 21 '22 at 14:31
What is *"gcc configure"*? – Peter Mortensen Oct 25 '22 at 20:28
OK, the OP has left the building (*"Last seen more than 9 years ago"*). Perhaps somebody else can chime in? – Peter Mortensen Oct 25 '22 at 21:07
[Using executable `./configure`](https://stackoverflow.com/questions/8132594/disable-werror-in-configure-file) (whatever that is)? – Peter Mortensen Oct 25 '22 at 21:22
OK, [./configure](https://en.wikipedia.org/wiki/Configure_script) is associated with Make (has nothing to do with GCC as such). – Peter Mortensen Oct 25 '22 at 21:34

score 0 · Answer 7 · edited Oct 25 '22 at 20:23

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Put "pragma warnings(off, "...")" into the offending parts of your code.

See http://www.adacore.com/2007/11/19/ada-gem-18/.

edited Oct 25 '22 at 20:23

Peter Mortensen

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answered Mar 11 '10 at 14:40

user275257

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The link is broken: *"The page you're looking for can't be found"* – Peter Mortensen Oct 25 '22 at 20:23
Re "`pragma warnings`": Do you mean something like [`#pragma GCC diagnostic`](https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html#index-pragma_002c-diagnostic)? – Peter Mortensen Oct 25 '22 at 20:27

How can I disable fail on warning when using GCC and Make?

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