-Wmissing-attributes: check that we avoid duplicates and false positives

The initial patch for PR 81824 fixed various possibilities of
-Wmissing-attributes reporting duplicates and false positives.  The
test that avoided them was a little obscure, though, so this patch
rewrites it into a more self-evident form.

The patch also adds a testcase that already passed, but that
explicitly covers some of the possibilities of reporting duplicates
and false positives that preexisting tests did not cover.


for  gcc/ChangeLog

	PR middle-end/81824
	* attribs.c (decls_mismatched_attributes): Simplify the logic
	that avoids duplicates and false positives.

for  gcc/testsuite/ChangeLog

	PR middle-end/81824
	* g++.dg/Wmissing-attributes-1.C: New.  Some of its fragments
	are from Martin Sebor.

From-SVN: r273563

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2019-07-17  Alexandre Oliva <oliva@adacore.com>
+
+	PR middle-end/81824
+	* attribs.c (decls_mismatched_attributes): Simplify the logic
+	that avoids duplicates and false positives.
+
 2019-07-17  John David Anglin  <danglin@gcc.gnu.org>
 
 	* config/pa/pa.c (pa_som_asm_init_sections): Don't force all constant

gcc/attribs.c

@@ -1931,15 +1931,19 @@ decls_mismatched_attributes (tree tmpl, tree decl, tree attrlist,
 	  if (!has_attribute (tmpls[j], tmpl_attrs[j], blacklist[i]))
 	    continue;
 
+	  bool found = false;
 	  unsigned kmax = 1 + !!decl_attrs[1];
 	  for (unsigned k = 0; k != kmax; ++k)
 	    {
 	      if (has_attribute (decls[k], decl_attrs[k], blacklist[i]))
-		break;
-
-	      if (!k && kmax > 1)
-		continue;
+		{
+		  found = true;
+		  break;
+		}
+	    }
 
+	  if (!found)
+	    {
 	      if (nattrs)
 		pp_string (attrstr, ", ");
 	      pp_begin_quote (attrstr, pp_show_color (global_dc->printer));
@@ -1947,6 +1951,8 @@ decls_mismatched_attributes (tree tmpl, tree decl, tree attrlist,
 	      pp_end_quote (attrstr, pp_show_color (global_dc->printer));
 	      ++nattrs;
 	    }
+
+	  break;
 	}
     }
 

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2019-07-17  Alexandre Oliva <oliva@adacore.com>
+
+	PR middle-end/81824
+	* g++.dg/Wmissing-attributes-1.C: New.  Some of its fragments
+	are from Martin Sebor.
+
 2019-07-17  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/90455

gcc/testsuite/g++.dg/Wmissing-attributes-1.C

@@ -0,0 +1,66 @@
+// { dg-do compile }
+// { dg-options "-Wmissing-attributes" }
+
+#define ATTR(list)   __attribute__ (list)
+
+/* Type attributes are normally absent in template functions, and the
+   mere presence of any such attribute used to cause the
+   -Wmissing-attributes checks, that checked for attributes typically
+   associated with functions rather than types, to report any missing
+   attributes twice: once for the specialization attribute list, once
+   for its type attribute list.
+
+   This test uses both decl and type attributes to exercise the code
+   that avoids reporting duplicates, in ways that failed in the past
+   but that were not covered in other tests.  */
+typedef void* ATTR ((alloc_size (1))) f_type (int);
+
+template <class T>
+f_type
+ATTR ((malloc))
+missing_malloc;            // { dg-message "missing primary template attribute .malloc." }
+
+template <>
+f_type
+missing_malloc<char>;      // { dg-warning "explicit specialization .\[^\n\r\]+. may be missing attributes" }
+
+
+/* Check that even an attribute that appears in both lists (decl and
+   type) in a template declaration is reported as missing only
+   once.  */
+
+template <class T>
+f_type
+ATTR ((alloc_size (1))) // In both attr lists, decl's and type's.
+missing_alloc_size;            // { dg-message "missing primary template attribute .alloc_size." }
+
+template <>
+void *
+missing_alloc_size<char>(int); // { dg-warning "explicit specialization .\[^\n\r\]+. may be missing attributes" }
+
+
+/* Check that even an attribute that appears in both lists (decl and
+   type) is not reported as missing if it's present only in the type
+   list.  */
+
+template <class T>
+f_type
+ATTR ((alloc_size (1))) // In both attr lists, decl's and type's.
+missing_nothing;
+
+template <>
+f_type
+missing_nothing<char>;
+
+
+/* For completeness, check that a type attribute is matched by a decl
+   attribute in the specialization.  */
+
+template <class T>
+f_type
+missing_nothing2;
+
+template <>
+void *
+ATTR ((alloc_size (1)))
+missing_nothing2<char>(int);