Re: [PATCH 1/4] introduce diagnostic infrastructure changes (PR 98512)

[David Malcolm <dmalcolm@redhat.com>]

On Tue, 2021-06-15 at 17:00 -0600, Martin Sebor wrote:
> On 6/11/21 11:04 AM, David Malcolm wrote:
> > On Thu, 2021-06-10 at 17:26 -0600, Martin Sebor wrote:
> > > This diff introduces the diagnostic infrastructure changes to
> > > support
> > > controlling warnings at any call site in the inlining stack and
> > > printing
> > > the inlining context without the %K and %G directives.
> > 
> > Thanks for working on this, looks very promising.
> > 
> > > Improve warning suppression for inlined functions.
> > > 
> > > Resolves:
> > > PR middle-end/98871 - Cannot silence -Wmaybe-uninitialized at
> > > declaration site
> > > PR middle-end/98512 - #pragma GCC diagnostic ignored ineffective in
> > > conjunction with alias attribute
> > 
> > Am I right in thinking that you add test coverage for both of these
> > in
> > patch 2 of the kit?
> 
> Yes, the tests depend on the changes in patch 2 (some existing tests
> fail with just patch 1 applied because the initial location passed
> to warning_t() is different than with it).
> 
> 

[...]

> > 
> 
> 
> Yep, thanks.  Please see the attached revision.
> 
> Martin

Various nits inline below:

> diff --git a/gcc/diagnostic.c b/gcc/diagnostic.c
> index d58586f2526..3a22d4d26a6 100644
> --- a/gcc/diagnostic.c
> +++ b/gcc/diagnostic.c
> @@ -991,51 +991,93 @@ print_parseable_fixits (pretty_printer *pp, rich_location *richloc,
>    pp_set_prefix (pp, saved_prefix);
>  }
>  
> -/* Update the diag_class of DIAGNOSTIC based on its location
> -   relative to any
> +/* Update the inlininig context in CONTEXT for a DIAGNOSTIC.  */
                 ^^^^^^^^^^^^^^^^^

It's inlining_info now, so please update this comment.

> +
> +static void
> +update_inlining_context (diagnostic_context *context,
> +			 diagnostic_info *diagnostic)

...and please rename to "get_any_inlining_info".

> +{
> +  auto &ilocs = diagnostic->m_iinfo.m_ilocs;
> +
> +  if (context->set_locations_cb)
> +    {
> +      /* Retrieve the locations into which the expression about to be
> +	 diagnosed has been inlined, including those of all the callers
> +	 all the way down the inlining stack.  */
> +      context->set_locations_cb (context, diagnostic);
> +      location_t loc = diagnostic->m_iinfo.m_ilocs.last ();


> +      if (diagnostic->m_iinfo.m_ao && loc != UNKNOWN_LOCATION)
> +	diagnostic->message.set_location (0, loc, SHOW_RANGE_WITH_CARET);

What is the purpose of the above two lines of code?
(I believe it's to replace the %G/%K stuff, right?)
Please can you add a suitable comment.


> +    }
> +  else
> +    {
> +      /* When there's no callback use just the one location provided
> +	 by the caller of the diagnostic function.  */
> +      location_t loc = diagnostic_location (diagnostic);
> +      ilocs.safe_push (loc);
> +      diagnostic->m_iinfo.m_allsyslocs = in_system_header_at (loc);
> +    }
> +}
> +
> +/* Update the kind of DIAGNOSTIC based on its location(s), including
> +   any of those in its inlining context, relative to any
                                   ^^^^^^^

"stack" rather than "context" here; I think we're overusing the word "context".

>       #pragma GCC diagnostic
>     directives recorded within CONTEXT.
>  
> -   Return the new diag_class of DIAGNOSTIC if it was updated, or
> -   DK_UNSPECIFIED otherwise.  */
> +   Return the new kind of DIAGNOSTIC if it was updated, or DK_UNSPECIFIED
> +   otherwise.  */
>  
>  static diagnostic_t
>  update_effective_level_from_pragmas (diagnostic_context *context,
>  				     diagnostic_info *diagnostic)
>  {
> -  diagnostic_t diag_class = DK_UNSPECIFIED;
> -
> -  if (context->n_classification_history > 0)
> +  if (diagnostic->m_iinfo.m_allsyslocs && !context->dc_warn_system_headers)
>      {
> -      location_t location = diagnostic_location (diagnostic);
> +      /* Ignore the diagnostic if all the inlined locations are
> +	 in system headers and -Wno-system-headers is in effect.  */
> +      diagnostic->kind = DK_IGNORED;
> +      return DK_IGNORED;
> +    }
>  
> +  if (context->n_classification_history <= 0)
> +    return DK_UNSPECIFIED;
> +
> +  /* Iterate over the locations, checking the diagnostic disposition
> +     for the diagnostic at each.  If it's explicitly set as opposed
> +     to unspecified, update the disposition for this instance of
> +     the diagnostic and return it.  */
> +  for (location_t loc: diagnostic->m_iinfo.m_ilocs)
> +    {
>        /* FIXME: Stupid search.  Optimize later. */
>        for (int i = context->n_classification_history - 1; i >= 0; i --)
>  	{
> -	  if (linemap_location_before_p
> -	      (line_table,
> -	       context->classification_history[i].location,
> -	       location))
> +	  const diagnostic_classification_change_t &hist
> +	    = context->classification_history[i];
> +
> +	  location_t pragloc = hist.location;
> +	  if (!linemap_location_before_p (line_table, pragloc, loc))
> +	    continue;
> +
> +	  if (hist.kind == (int) DK_POP)
>  	    {
> -	      if (context->classification_history[i].kind == (int) DK_POP)
> -		{
> -		  i = context->classification_history[i].option;
> -		  continue;
> -		}
> -	      int option = context->classification_history[i].option;
> -	      /* The option 0 is for all the diagnostics.  */
> -	      if (option == 0 || option == diagnostic->option_index)
> -		{
> -		  diag_class = context->classification_history[i].kind;
> -		  if (diag_class != DK_UNSPECIFIED)
> -		    diagnostic->kind = diag_class;
> -		  break;
> -		}
> +	      /* Move on to the next region.  */
> +	      i = hist.option;
> +	      continue;
> +	    }
> +
> +	  int option = hist.option;
> +	  /* The option 0 is for all the diagnostics.  */
> +	  if (option == 0 || option == diagnostic->option_index)
> +	    {
> +	      diagnostic_t kind = hist.kind;
> +	      if (kind != DK_UNSPECIFIED)
> +		diagnostic->kind = kind;
> +	      return kind;
>  	    }
>  	}
>      }
>  
> -  return diag_class;
> +  return DK_UNSPECIFIED;
>  }
>  
>  /* Generate a URL string describing CWE.  The caller is responsible for
> @@ -1129,6 +1171,9 @@ static bool
>  diagnostic_enabled (diagnostic_context *context,
>  		    diagnostic_info *diagnostic)
>  {
> +  /* Update the inlining context for this diagnostic.  */
> +  update_inlining_context (context, diagnostic);

Please rename as described above.

[...]

Dave