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Re: GDB 8.1 build error


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....  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


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