how to debug go build errors

how to debug go build errors

[Martin Sebor]

Hi Ian,

While testing what should be an innocuous patch to add LTO
to a bunch of middle-end warning options

   https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00381.html

I get Go errors during ordinary bootstrap about undefined names
for errno constants:

/opt/notnfs/msebor/src/gcc/84212/libgo/go/syscall/env_unix.go:96:10: 
error: reference to undefined name ‘EINVAL’

Bootstrapping all other front ends (including Ada and Brig),
succeeds and there are no regressions in the test suite.

I have no experience with Go.  Does anything about the patch
jump out at you that could be causing this?  If not, can you
suggest how to debug it?

Thanks
Martin

Re: how to debug go build errors

[Ian Lance Taylor]

On Thu, Feb 8, 2018 at 3:24 PM, Martin Sebor <msebor@gmail.com> wrote:
>
> While testing what should be an innocuous patch to add LTO
> to a bunch of middle-end warning options
>
>   https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00381.html
>
> I get Go errors during ordinary bootstrap about undefined names
> for errno constants:
>
> /opt/notnfs/msebor/src/gcc/84212/libgo/go/syscall/env_unix.go:96:10: error:
> reference to undefined name ‘EINVAL’
>
> Bootstrapping all other front ends (including Ada and Brig),
> succeeds and there are no regressions in the test suite.
>
> I have no experience with Go.  Does anything about the patch
> jump out at you that could be causing this?  If not, can you
> suggest how to debug it?

No, I don't see why your patch would cause this problem.

EINVAL should be defined in the generated file
TARGET/libgo/sysinfo.go.  You should see, among many others, the lines
    const _EINVAL = 22
and
    const EINVAL = Errno(_EINVAL)

That file is built by the shell script libgo/mksysinfo.sh, which looks
at the generated file TARGET/libgo/gen-sysinfo.go.  The gen-sysinfo.go
file is built by running the C compiler with the -fdump-go-spec option
on the file libgo/sysinfo.c (essentially GCC_FOR_TARGET
-fdump-go-spec=gen-sysinfo.go -std=gnu99 -S sysinfo.c).  I guess
something along that chain has broken, but I don't know what.

Ian

Re: how to debug go build errors

[Martin Sebor]

Never mind.  I see the problem.  I overlooked a few failures
in the preprocessor test suite.  Turns out the patch accidentally
deletes the -d option from the .opt file.  I didn't notice it in
the diff because the "-d" at the beginning of the line looks just
like the option is still there!

@@ -1186,7 +1186,6 @@ ansi
  C ObjC C++ ObjC++
  A synonym for -std=c89 (for C) or -std=c++98 (for C++).

-d
  C ObjC C++ ObjC++ Joined
  ; Documented in common.opt.  FIXME - what about -dI, -dD, -dN and -dD?

Sorry for the noise!

On 02/08/2018 04:24 PM, Martin Sebor wrote:
> Hi Ian,
>
> While testing what should be an innocuous patch to add LTO
> to a bunch of middle-end warning options
>
>   https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00381.html
>
> I get Go errors during ordinary bootstrap about undefined names
> for errno constants:
>
> /opt/notnfs/msebor/src/gcc/84212/libgo/go/syscall/env_unix.go:96:10:
> error: reference to undefined name ‘EINVAL’
>
> Bootstrapping all other front ends (including Ada and Brig),
> succeeds and there are no regressions in the test suite.
>
> I have no experience with Go.  Does anything about the patch
> jump out at you that could be causing this?  If not, can you
> suggest how to debug it?
>
> Thanks
> Martin

Re: how to debug go build errors

[Martin Sebor]

On 02/08/2018 05:39 PM, Ian Lance Taylor wrote:
> On Thu, Feb 8, 2018 at 3:24 PM, Martin Sebor <msebor@gmail.com> wrote:
>>
>> While testing what should be an innocuous patch to add LTO
>> to a bunch of middle-end warning options
>>
>>   https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00381.html
>>
>> I get Go errors during ordinary bootstrap about undefined names
>> for errno constants:
>>
>> /opt/notnfs/msebor/src/gcc/84212/libgo/go/syscall/env_unix.go:96:10: error:
>> reference to undefined name ‘EINVAL’
>>
>> Bootstrapping all other front ends (including Ada and Brig),
>> succeeds and there are no regressions in the test suite.
>>
>> I have no experience with Go.  Does anything about the patch
>> jump out at you that could be causing this?  If not, can you
>> suggest how to debug it?
>
> No, I don't see why your patch would cause this problem.
>
> EINVAL should be defined in the generated file
> TARGET/libgo/sysinfo.go.  You should see, among many others, the lines
>     const _EINVAL = 22
> and
>     const EINVAL = Errno(_EINVAL)
>
> That file is built by the shell script libgo/mksysinfo.sh, which looks
> at the generated file TARGET/libgo/gen-sysinfo.go.  The gen-sysinfo.go
> file is built by running the C compiler with the -fdump-go-spec option
> on the file libgo/sysinfo.c (essentially GCC_FOR_TARGET
> -fdump-go-spec=gen-sysinfo.go -std=gnu99 -S sysinfo.c).  I guess
> something along that chain has broken, but I don't know what.

I've figured out what was causing it -- a silly typo.  (Our
emails must have crossed by barely a couple of minutes).
Thanks for the quick reply though!

Martin