c++: DECL_FRIEND_P cleanup

DECL_FRIEND_P's meaning has changed over time.  It now (almost) means
the the friend function decl has not been met via an explicit decl.
This completes that transition, renaming it to DECL_UNIQUE_FRIEND_P,
so one doesn't think it is the sole indicator of friendliness (plenty
of friends do not have the flag set).  This allows reduction in the
complexity of managing the field -- all in duplicate_decls now.

	gcc/cp/
	* cp-tree.h (struct lang_decl_fn): Adjust context comment.
	(DECL_FRIEND_P): Replace with ...
	(DECL_UNIQUE_FRIEND_P): ... this.  Only for FUNCTION_DECLs.
	(DECL_FRIEND_CONTEXT): Adjust.
	* class.c (add_implicitly_declared_members): Detect friendly
	spaceship from context.
	* constraint.cc (remove_constraints): Use a checking assert.
	(maybe_substitute_reqs_for): Use DECL_UNIQUE_FRIEND_P.
	* decl.c (check_no_redeclaration_friend_default_args):
	DECL_UNIQUE_FRIEND_P is signficant, not hiddenness.
	(duplicate_decls): Adjust DECL_UNIQUE_FRIEND_P clearing.
	(redeclaration_error_message): Use DECL_UNIQUE_FRIEND_P.
	(start_preparsed_function): Correct in-class friend processing.
	Refactor some initializers.
	(grokmethod): Directly check friend decl-spec.
	* decl2.c (grokfield): Check DECL_UNIQUE_FRIEND_P.
	* friend.c (do_friend): Set DECL_UNIQUE_FRIEND_P first, remove
	extraneous conditions.  Don't re set it afterwards.
	* name-lookup.c (lookup_elaborated_type_1): Simplify revealing
	code.
	(do_pushtag): Likewise.
	* pt.c (optimize_specialization_lookup_p): Check
	DECL_UNIQUE_FRIEND_P.
	(push_template_decl): Likewise.  Drop unneeded friend setting.
	(type_dependent_expression_p): Check DECL_UNIQUE_FRIEND_P.
	libcc1/
	* libcp1plugin.cc (plugin_add_friend): Set DECL_UNIQUE_FRIEND_P.

1 files changed, 15 insertions, 9 deletions

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 4672561..5c06ac3 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -2736,12 +2736,14 @@ struct GTY(()) lang_decl_fn {
      thunked to function decl.  */
   tree befriending_classes;
 
-  /* For a non-virtual FUNCTION_DECL, this is
-     DECL_FRIEND_CONTEXT.  For a virtual FUNCTION_DECL for which
+  /* For a virtual FUNCTION_DECL for which
      DECL_THIS_THUNK_P does not hold, this is DECL_THUNKS. Both
      this pointer and result pointer adjusting thunks are
      chained here.  This pointer thunks to return pointer thunks
-     will be chained on the return pointer thunk.  */
+     will be chained on the return pointer thunk.
+     For a DECL_CONSTUCTOR_P FUNCTION_DECL, this is the base from
+     whence we inherit.  Otherwise, it is the class in which a
+     (namespace-scope) friend is defined (if any).   */
   tree context;
 
   union lang_decl_u5
@@ -3088,10 +3090,14 @@ struct GTY(()) lang_decl {
   (DECL_LANG_SPECIFIC (VAR_OR_FUNCTION_DECL_CHECK (DECL)) \
    ->u.base.odr_used)
 
-/* Nonzero for DECL means that this decl is just a friend declaration,
-   and should not be added to the list of members for this class.  */
-#define DECL_FRIEND_P(NODE) \
-  (DECL_LANG_SPECIFIC (TYPE_FUNCTION_OR_TEMPLATE_DECL_CHECK (NODE)) \
+/* Nonzero for FUNCTION_DECL means that this is a friend that is
+   either not pushed into a namespace/looked up in a class (because it
+   is a dependent type, in an uninstantiated template), or it has
+   /only/ been subject to hidden friend injection from one or more
+   befriending classes.  Once another decl matches, the flag is
+   cleared.  There are requirements on its default parms.  */
+#define DECL_UNIQUE_FRIEND_P(NODE) \
+  (DECL_LANG_SPECIFIC (FUNCTION_DECL_CHECK (NODE)) \
    ->u.base.friend_or_tls)
 
 /* Nonzero if the thread-local variable was declared with __thread as
@@ -3290,8 +3296,8 @@ struct GTY(()) lang_decl {
 
    the DECL_FRIEND_CONTEXT for `f' will be `S'.  */
 #define DECL_FRIEND_CONTEXT(NODE)				\
-  ((DECL_DECLARES_FUNCTION_P (NODE)				\
-    && DECL_FRIEND_P (NODE) && !DECL_FUNCTION_MEMBER_P (NODE))	\
+  ((DECL_DECLARES_FUNCTION_P (NODE) && !DECL_VIRTUAL_P (NODE)	\
+    && !DECL_CONSTRUCTOR_P (NODE))				\
    ? LANG_DECL_FN_CHECK (NODE)->context				\
    : NULL_TREE)