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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?

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  • 1
    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? Commented Mar 10, 2010 at 3:15
  • 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 Commented Oct 23, 2022 at 15:58

7 Answers 7

Reset to default
56

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

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16

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).

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7

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.

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3 Comments

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!
What is "RTS"? Runtime system?
@PeterMortensen, yes.
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.

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3

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.

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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.
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.
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.
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.
2

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

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

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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
What is "gcc configure"?
OK, the OP has left the building ("Last seen more than 9 years ago"). Perhaps somebody else can chime in?
Using executable ./configure (whatever that is)?
OK, ./configure is associated with Make (has nothing to do with GCC as such).
0

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

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

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The link is broken: "The page you're looking for can't be found"
Re "pragma warnings": Do you mean something like #pragma GCC diagnostic?
But I want the warning. I just don't want them as errors while developing half finished code.

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