Re: [PATCH] ltmain.in: don't suppress output for PIC compilations

[Nick Bowler]

On 2024-08-15 12:13, Sam James wrote:
> Ileana Dumitrescu <ileanadumitrescu95@gmail.com> writes:
>> However, you could also just specify '-no-suppress' when compiling
>> rather than changing the default behaviour.
> 
> (Is there a way to do this globally? If I put it in CFLAGS globally,
> won't this break if libtool isn't used for a package, given GCC or Clang
> will see it and bail out?)

Automake provides LIBTOOLFLAGS and AM_LIBTOOLFLAGS for this kind of
purpose but unfortunately it is not in the right position to pass
mode-specific options like -no-suppress.

I think it would be a big improvement to allow most mode-specific options
to appear earlier on the libtool command line.  Then you could just do

  make LIBTOOLFLAGS=-no-suppress

and it'd work.

> I really feel like the current behaviour is unexpected and surprising,
> and perhaps it was based on the (wrong) idea that the -fPIC vs non-PIC
> build will produce identical warnings and if one fails, the other will
> fail, but that's not true at least with modern compilers.

Can we fix the compilers instead?  Why does PIC compilation suppress
warnings?  That behaviour seems unexpected and surprising.

> That's the part I want to discuss -- does anyone actually think the
> suppression is still a good idea? 

Duplicate output sounds very annoying so yes, I think it is a good idea
to suppress duplicate output.

If you change the default, maybe just print the differences on the
second run.  This might be as simple as just running diff on the
output of both runs.

Cheers,
  Nick