[gcc r11-6592] c++, abi: Fix abi_tag attribute handling [PR98481]

[gcc r11-6592] c++, abi: Fix abi_tag attribute handling [PR98481]

[Jason Merrill]

https://gcc.gnu.org/g:3dd0d3ee1d2a988e7f3a3e8f009fcf328f16d2ed

commit r11-6592-g3dd0d3ee1d2a988e7f3a3e8f009fcf328f16d2ed
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 7 17:47:18 2021 +0100

    c++, abi: Fix abi_tag attribute handling [PR98481]
    
    In GCC10 cp_walk_subtrees has been changed to walk template arguments.
    As the following testcase, that changed the mangling of some functions.
    I believe the previous behavior that find_abi_tags_r doesn't recurse into
    template args has been the correct one, but setting *walk_subtrees = 0
    for the types and handling the types subtree walking manually in
    find_abi_tags_r looks too hard, there are a lot of subtrees and details what
    should and shouldn't be walked, both in tree.c (walk_type_fields there,
    which is static) and in cp_walk_subtrees itself.
    
    The following patch abuses the fact that *walk_subtrees is an int to
    tell cp_walk_subtrees it shouldn't walk the template args.
    
    Co-authored-by: Jason Merrill <jason@redhat.com>
    
    gcc/cp/ChangeLog:
    
            PR c++/98481
            * class.c (find_abi_tags_r): Set *walk_subtrees to 2 instead of 1
            for types.
            (mark_abi_tags_r): Likewise.
            * decl2.c (min_vis_r): Likewise.
            * tree.c (cp_walk_subtrees): If *walk_subtrees_p is 2, look through
            typedefs.
    
    gcc/testsuite/ChangeLog:
    
            PR c++/98481
            * g++.dg/abi/abi-tag24.C: New test.

Diff:
---
 gcc/cp/class.c                       |  8 ++++++++
 gcc/cp/decl2.c                       |  7 ++++---
 gcc/cp/tree.c                        | 22 ++++++++++++++++------
 gcc/testsuite/g++.dg/abi/abi-tag24.C | 17 +++++++++++++++++
 4 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index c41ac7deefe..00c0dba0a55 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -1507,6 +1507,10 @@ mark_or_check_tags (tree t, tree *tp, abi_tag_data *p, bool val)
 static tree
 find_abi_tags_r (tree *tp, int *walk_subtrees, void *data)
 {
+  if (TYPE_P (*tp) && *walk_subtrees == 1)
+    /* Tell cp_walk_subtrees to look though typedefs.  */
+    *walk_subtrees = 2;
+
   if (!OVERLOAD_TYPE_P (*tp))
     return NULL_TREE;
 
@@ -1527,6 +1531,10 @@ find_abi_tags_r (tree *tp, int *walk_subtrees, void *data)
 static tree
 mark_abi_tags_r (tree *tp, int *walk_subtrees, void *data)
 {
+  if (TYPE_P (*tp) && *walk_subtrees == 1)
+    /* Tell cp_walk_subtrees to look though typedefs.  */
+    *walk_subtrees = 2;
+
   if (!OVERLOAD_TYPE_P (*tp))
     return NULL_TREE;
 
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index b10671091b5..b087753cfba 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -2358,9 +2358,6 @@ min_vis_r (tree *tp, int *walk_subtrees, void *data)
   int this_vis = VISIBILITY_DEFAULT;
   if (! TYPE_P (*tp))
     *walk_subtrees = 0;
-  else if (typedef_variant_p (*tp))
-    /* Look through typedefs despite cp_walk_subtrees.  */
-    this_vis = type_visibility (DECL_ORIGINAL_TYPE (TYPE_NAME (*tp)));
   else if (OVERLOAD_TYPE_P (*tp)
 	   && !TREE_PUBLIC (TYPE_MAIN_DECL (*tp)))
     {
@@ -2379,6 +2376,10 @@ min_vis_r (tree *tp, int *walk_subtrees, void *data)
   if (this_vis > *vis_p)
     *vis_p = this_vis;
 
+  /* Tell cp_walk_subtrees to look through typedefs.  */
+  if (*walk_subtrees == 1)
+    *walk_subtrees = 2;
+
   return NULL;
 }
 
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 82027cc9abf..c536eb581a7 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -5146,16 +5146,26 @@ cp_walk_subtrees (tree *tp, int *walk_subtrees_p, walk_tree_fn func,
 
   if (TYPE_P (*tp))
     {
-      /* Walk into template args without looking through typedefs.  */
-      if (tree ti = TYPE_TEMPLATE_INFO_MAYBE_ALIAS (*tp))
-	WALK_SUBTREE (TI_ARGS (ti));
-      /* Don't look through typedefs; walk_tree_fns that want to look through
-	 typedefs (like min_vis_r) need to do that themselves.  */
-      if (typedef_variant_p (*tp))
+      /* If *WALK_SUBTREES_P is 1, we're interested in the syntactic form of
+	 the argument, so don't look through typedefs, but do walk into
+	 template arguments for alias templates (and non-typedefed classes).
+
+	 If *WALK_SUBTREES_P > 1, we're interested in type identity or
+	 equivalence, so look through typedefs, ignoring template arguments for
+	 alias templates, and walk into template args of classes.
+
+	 See find_abi_tags_r for an example of setting *WALK_SUBTREES_P to 2
+	 when that's the behavior the walk_tree_fn wants.  */
+      if (*walk_subtrees_p == 1 && typedef_variant_p (*tp))
 	{
+	  if (tree ti = TYPE_ALIAS_TEMPLATE_INFO (*tp))
+	    WALK_SUBTREE (TI_ARGS (ti));
 	  *walk_subtrees_p = 0;
 	  return NULL_TREE;
 	}
+
+      if (tree ti = TYPE_TEMPLATE_INFO (*tp))
+	WALK_SUBTREE (TI_ARGS (ti));
     }
 
   /* Not one of the easy cases.  We must explicitly go through the
diff --git a/gcc/testsuite/g++.dg/abi/abi-tag24.C b/gcc/testsuite/g++.dg/abi/abi-tag24.C
new file mode 100644
index 00000000000..c758544b090
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/abi-tag24.C
@@ -0,0 +1,17 @@
+// PR c++/98481
+// { dg-do compile { target c++11 } }
+inline namespace N __attribute ((__abi_tag__ ("myabi")))
+{
+  struct A {};
+}
+template <typename T>
+struct B { typedef int size_type; };
+struct S1 { B<A>::size_type foo () const { return 1; } };
+struct S2 { B<A>::size_type foo () const; };
+int S2::foo () const { return 2; }
+int (S1::*f1) () const = &S1::foo;
+int (S2::*f2) () const = &S2::foo;
+
+// { dg-final { scan-assembler "_ZNK2S13fooEv" } }
+// { dg-final { scan-assembler "_ZNK2S23fooEv" } }
+// { dg-final { scan-assembler-not "_ZNK2S13fooB5myabiEv" } }