Re: Surprising behavior of suppress_type drop = yes

[Mark Wielaard <mark@klomp.org>]

[-- Attachment #1: Type: text/plain, Size: 2062 bytes --]

Hi Dodji,

On Mon, 2020-04-06 at 19:15 +0200, Dodji Seketeli wrote:
> > Note how abidiff treats the function return type and parameters changed
> > from void * to Foo * as disappearing.
> > 
> > Is there another way to achieve what I want/need?
> 
> I think there is a non-documented way to do this, yes.  It hasn't been
> yet documented because nobody expressed the need for it yet.
> 
> Basically you want to do this:
> 
> [suppress_type]
>   label = "Artificial·private·types·suppression·specification"

Assuming those fancy dots are actually spaces.

>   source_location_not_in = list.h, of.h, public.h, headers.h
>   drop = yes
> 
> The 'label' property there is important and it needs to have that exact
> string value.
> 
> Libabigail generates this kind of suppression specifications internally
> to handle types that it considers to be private types, namely, types
> that are defined in files specified by --headers-dir{1,2}.
> 
> So I guess you can use that undocumented feature for now.

It doesn't seem to change anything for my example.
I assume it does for you? Can you attach the xml abi file it is
supposed to generate? Mine still looks like the attached with missing
return types and arguments where there should be pointers to Foo. Maybe
my suppression file still isn't correct? I attached both.

> > Or can we have a "drop mode" that treats handles to dropped types a
> > simple void pointers instead?
> 
> I think what you'd need, really, is a combination of:
> 
>     1/ a new --header-files{1,2} option
>     2/ an "opaque = yes" attribute in the suppression specification.
> 
> I think either 1/ or 2/ should work, but it'd be nice to have both.
> 
> If you think that suggession holds water, then we should probably
> file a
> bug to add this new feature.

Why not fix the default?

I am trying to figure out why the command line option is different from
the suppress_type default way of handling drop. And when that default
way of working is actually useful?

Thanks,

Mark

[-- Attachment #2: libfoo.abi --]
[-- Type: text/plain, Size: 2305 bytes --]

<abi-corpus architecture='elf-amd-x86_64'>
  <elf-needed>
    <dependency name='libc.so.6'/>
  </elf-needed>
  <elf-function-symbols>
    <elf-symbol name='_fini' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
    <elf-symbol name='_init' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
    <elf-symbol name='create_foo' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
    <elf-symbol name='destroy_foo' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
    <elf-symbol name='get_foo' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
    <elf-symbol name='set_foo' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
  </elf-function-symbols>
  <abi-instr version='1.0' address-size='64' path='foo.c' language='LANG_C99'>
    <type-decl name='int' size-in-bits='32' id='type-id-1'/>
    <type-decl name='void' id='type-id-2'/>
    <function-decl name='get_foo' mangled-name='get_foo' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='get_foo'>
      <return type-id='type-id-1'/>
    </function-decl>
    <function-decl name='set_foo' mangled-name='set_foo' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='set_foo'>
      <parameter type-id='type-id-1' name='num'/>
      <return type-id='type-id-2'/>
    </function-decl>
    <function-decl name='destroy_foo' mangled-name='destroy_foo' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='destroy_foo'>
      <return type-id='type-id-2'/>
    </function-decl>
    <function-decl name='create_foo' mangled-name='create_foo' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='create_foo'>
      <return type-id='type-id-2'/>
    </function-decl>
    <function-decl name='free' mangled-name='free' visibility='default' binding='global' size-in-bits='64'>
      <return type-id='type-id-2'/>
    </function-decl>
    <function-decl name='malloc' mangled-name='malloc' visibility='default' binding='global' size-in-bits='64'>
      <return type-id='type-id-2'/>
    </function-decl>
  </abi-instr>
</abi-corpus>

[-- Attachment #3: libfoo.supp --]
[-- Type: text/plain, Size: 125 bytes --]

[suppress_type]
  label = "Artificial private types suppression specification"
  source_location_not_in = foo.h
  drop = yes