[gcc(refs/users/aoliva/heads/strub)] Improve integration of strub with type systems

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:cffad65eee42ae93fc6b46c119facce5e626f67d

commit cffad65eee42ae93fc6b46c119facce5e626f67d
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Sat Oct 30 07:06:41 2021 -0300

    Improve integration of strub with type systems
    
    This is a patch that complements changes to front-end and back-end,
    adjusting the build system to build a newly-added package, and
    improving handling of the strub attribute to warn on composite types.
    
    [changelog]
            * gcc-interface/Make-lang.in: (GNAT_ADA_OBJS): Add
            ada/strub.o.
            * gcc-interface/utils.c (handle_strub_attribute): Simplify
            check for pointer-to-function types.  Warn when applied to
            composite types.
    
    TN: U611-048
    Change-Id: I05a28cbe8186a33d810a9d2adadc0aa4905c5ddc

Diff:
---
 gcc/ada/gcc-interface/Make-lang.in |  1 +
 gcc/ada/gcc-interface/utils.c      | 20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/gcc/ada/gcc-interface/Make-lang.in b/gcc/ada/gcc-interface/Make-lang.in
index ab5fb72623b..ae5158a5484 100644
--- a/gcc/ada/gcc-interface/Make-lang.in
+++ b/gcc/ada/gcc-interface/Make-lang.in
@@ -440,6 +440,7 @@ GNAT_ADA_OBJS =	\
  ada/sprint.o	\
  ada/stand.o	\
  ada/stringt.o	\
+ ada/strub.o	\
  ada/style.o	\
  ada/styleg.o	\
  ada/stylesw.o	\
diff --git a/gcc/ada/gcc-interface/utils.c b/gcc/ada/gcc-interface/utils.c
index fb9efb23eb9..54fb88a1ad7 100644
--- a/gcc/ada/gcc-interface/utils.c
+++ b/gcc/ada/gcc-interface/utils.c
@@ -6616,9 +6616,7 @@ handle_strub_attribute (tree *node, tree name,
 {
   bool enable = true;
 
-  if (args
-      && POINTER_TYPE_P (*node)
-      && FUNC_OR_METHOD_TYPE_P (TREE_TYPE (*node)))
+  if (args && FUNCTION_POINTER_TYPE_P (*node))
     *node = TREE_TYPE (*node);
 
   if (args && FUNC_OR_METHOD_TYPE_P (*node))
@@ -6660,6 +6658,22 @@ handle_strub_attribute (tree *node, tree name,
       enable = false;
     }
 
+  /* Warn about unmet expectations that the strub attribute works like a
+     qualifier.  ??? Could/should we extend it to the element/field types
+     here?  */
+  if (TREE_CODE (*node) == ARRAY_TYPE
+      || VECTOR_TYPE_P (*node)
+      || TREE_CODE (*node) == COMPLEX_TYPE)
+    warning (OPT_Wattributes,
+	     "attribute %qE does not apply to elements"
+	     " of non-scalar type %qT",
+	     name, *node);
+  else if (RECORD_OR_UNION_TYPE_P (*node))
+    warning (OPT_Wattributes,
+	     "attribute %qE does not apply to fields"
+	     " of aggregate type %qT",
+	     name, *node);
+
   /* If we see a strub-enabling attribute, and we're at the default setting,
      implicitly or explicitly, note that the attribute was seen, so that we can
      reduce the compile-time overhead to nearly zero when the strub feature is