[C++ PATCH] __builtin_source_location ()

[David Malcolm]

On Fri, 2019-11-15 at 13:28 +0100, Jakub Jelinek wrote:
> On Thu, Nov 14, 2019 at 08:34:26PM +0100, Jakub Jelinek wrote:
> > The following WIP patch implements __builtin_source_location (),
> > which returns const void pointer to a std::source_location::__impl
> > struct that is required to contain __file, __function, __line and
> > __column
> > fields, the first two with const char * type, the latter some
> > integral type.
> 
> Here is hopefully final version, with the hashing implemented,
> __file renamed to __file_name and __function to __function_name to
> match
> how the standard names the methods and with testsuite coverage.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

[...snip...]

> --- gcc/cp/cp-gimplify.c.jj	2019-11-15 00:37:14.511247252 +0100
> +++ gcc/cp/cp-gimplify.c	2019-11-15 11:23:50.574203292 +0100
[...]
> @@ -2868,4 +2883,246 @@ process_stmt_hotness_attribute (tree std
>    return std_attrs;
>  }
>  
> +/* Helper of fold_builtin_source_location, return the
> +   std::source_location::__impl type after performing verification
> +   on it.  */
> +
> +static tree
> +get_source_location_impl (location_t loc)
> +{

FWIW, I found this function confusing at first, and wondered what the
purpose of LOC was (given that the function is building a type, rather
than an instance of that type).

Maybe add this to the leading comment:
  "LOC is used for reporting any errors."
(and if so, perhaps replace the various "error" with "error_at", though
that's rather academic).

Maybe rename the function to "get_source_location_impl_type" to
emphasize the distinction?

Hope this is constructive
Dave


> +  tree name = get_identifier ("source_location");
> +  tree decl = lookup_qualified_name (std_node, name);
> +  if (TREE_CODE (decl) != TYPE_DECL)
> +    {
> +      auto_diagnostic_group d;
> +      if (decl == error_mark_node || TREE_CODE (decl) == TREE_LIST)
> +	qualified_name_lookup_error (std_node, name, decl, loc);
> +      else
> +	error ("%qD is not a type", decl);
> +      return error_mark_node;
> +    }
> +  name = get_identifier ("__impl");
> +  tree type = TREE_TYPE (decl);
> +  decl = lookup_qualified_name (type, name);
> +  if (TREE_CODE (decl) != TYPE_DECL)
> +    {
> +      auto_diagnostic_group d;
> +      if (decl == error_mark_node || TREE_CODE (decl) == TREE_LIST)
> +	qualified_name_lookup_error (type, name, decl, loc);
> +      else
> +	error ("%qD is not a type", decl);
> +      return error_mark_node;
> +    }
> +  type = TREE_TYPE (decl);
> +  if (TREE_CODE (type) != RECORD_TYPE)
> +    {
> +      error ("%qD is not a class type", decl);
> +      return error_mark_node;
> +    }
> +
> +  int cnt = 0;
> +  for (tree field = TYPE_FIELDS (type);
> +       (field = next_initializable_field (field)) != NULL_TREE;
> +       field = DECL_CHAIN (field))
> +    {
> +      if (DECL_NAME (field) != NULL_TREE)
> +	{
> +	  const char *n = IDENTIFIER_POINTER (DECL_NAME (field));
> +	  if (strcmp (n, "__file_name") == 0
> +	      || strcmp (n, "__function_name") == 0)
> +	    {
> +	      if (TREE_TYPE (field) != const_string_type_node)
> +		{
> +		  error ("%qD does not have %<const char *%> type",
> field);
> +		  return error_mark_node;
> +		}
> +	      cnt++;
> +	      continue;
> +	    }
> +	  else if (strcmp (n, "__line") == 0 || strcmp (n, "__column")
> == 0)
> +	    {
> +	      if (TREE_CODE (TREE_TYPE (field)) != INTEGER_TYPE)
> +		{
> +		  error ("%qD does not have integral type", field);
> +		  return error_mark_node;
> +		}
> +	      cnt++;
> +	      continue;
> +	    }
> +	}
> +      cnt = 0;
> +      break;
> +    }
> +  if (cnt != 4)
> +    {
> +      error ("%<std::source_location::__impl%> does not contain only
> "
> +	     "non-static data members %<__file_name%>,
> %<__function_name%>, "
> +	     "%<__line%> and %<__column%>");
> +      return error_mark_node;
> +    }
> +  return build_qualified_type (type, TYPE_QUAL_CONST);
> +}

[...snip...]