Re: GDB 8.1 build error

Simon Marchi
2018-04-27T20:16:47Z

On 2018-04-27 16:00, Pedro Alves wrote:
> On 04/27/2018 08:18 PM, Simon Marchi wrote:
>> On 2018-04-27 15:08, Pedro Alves wrote:
>>> Oh, wait....Â  Your build line has no "-W" at all, it has "-w"
>>> instead??
>>> How did that happen?
>>
>> When --disable-build-warnings is used, we don't put any -W/-Wno-
>> flags:
>>
>> https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob;f=gdb/warning.m4;h=f176a3291aa68acf0122609531abb4652425525b;hb=HEAD#l62
>
> But then, we add "-w", and I'm surprised that "-w" did not disable
> all warnings, including "-Wc++11-narrowing". "-w" is supposed to mean
> disable all warnings. At least, that's how GCC behaves.
> Could that be a clang bug?

On clang at least, -Wnarrowing seems to generate an error by default, so
-w doesn't affect it. You get:

no flag: error
-Wno-error=narrowing: warning
-Wno-error=narrowing -w: silent

So in this case, we would still need either -Wno-error=narrowing or
-Wno-narrowing.

We can test if gcc behaves the same, we just need something that is an
error by default but we can downgrade to a warning. Do you have an idea
of such diagnostic?

Simon