c++: Fix implicit friend operator==.

It seems that in writing testcases for the operator<=> proposal I didn't
include any tests for implicitly declared friend operator==, and
consequently it didn't work.

2020-02-11  Jason Merrill  <jason@redhat.com>

	PR c++/93675
	* class.c (add_implicitly_declared_members): Use do_friend.
	* method.c (implicitly_declare_fn): Fix friend handling.
	(decl_remember_implicit_trigger_p): New.
	(synthesize_method): Use it.
	* decl2.c (mark_used): Use it.

1 files changed, 38 insertions, 9 deletions

diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index cfc37bc..790d570 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -1463,6 +1463,22 @@ build_comparison_op (tree fndecl, tsubst_flags_t complain)
     --cp_unevaluated_operand;
 }
 
+/* True iff DECL is an implicitly-declared special member function with no real
+   source location, so we can use its DECL_SOURCE_LOCATION to remember where we
+   triggered its synthesis.  */
+
+bool
+decl_remember_implicit_trigger_p (tree decl)
+{
+  if (!DECL_ARTIFICIAL (decl))
+    return false;
+  special_function_kind sfk = special_function_p (decl);
+  /* Inherited constructors have the location of their using-declaration, and
+     operator== has the location of the corresponding operator<=>.  */
+  return (sfk != sfk_inheriting_constructor
+	  && sfk != sfk_comparison);
+}
+
 /* Synthesize FNDECL, a non-static member function.   */
 
 void
@@ -1479,7 +1495,7 @@ synthesize_method (tree fndecl)
 
   /* Reset the source location, we might have been previously
      deferred, and thus have saved where we were first needed.  */
-  if (DECL_ARTIFICIAL (fndecl) && !DECL_INHERITED_CTOR (fndecl))
+  if (decl_remember_implicit_trigger_p (fndecl))
     DECL_SOURCE_LOCATION (fndecl)
       = DECL_SOURCE_LOCATION (TYPE_NAME (DECL_CONTEXT (fndecl)));
 
@@ -2717,9 +2733,15 @@ implicitly_declare_fn (special_function_kind kind, tree type,
     type_set_nontrivial_flag (type, kind);
 
   /* Create the function.  */
-  tree this_type = cp_build_qualified_type (type, this_quals);
-  fn_type = build_method_type_directly (this_type, return_type,
-					parameter_types);
+  if (friend_p)
+    fn_type = build_function_type (return_type, parameter_types);
+  else
+    {
+      tree this_type = cp_build_qualified_type (type, this_quals);
+      fn_type = build_method_type_directly (this_type, return_type,
+					    parameter_types);
+    }
+
   if (raises)
     {
       if (raises != error_mark_node)
@@ -2794,12 +2816,19 @@ implicitly_declare_fn (special_function_kind kind, tree type,
 	 inheriting constructor doesn't satisfy the requirements.  */
       constexpr_p = DECL_DECLARED_CONSTEXPR_P (inherited_ctor);
     }
-  /* Add the "this" parameter.  */
-  this_parm = build_this_parm (fn, fn_type, this_quals);
-  DECL_CHAIN (this_parm) = DECL_ARGUMENTS (fn);
-  DECL_ARGUMENTS (fn) = this_parm;
 
-  grokclassfn (type, fn, kind == sfk_destructor ? DTOR_FLAG : NO_SPECIAL);
+  if (friend_p)
+    DECL_CONTEXT (fn) = DECL_CONTEXT (pattern_fn);
+  else
+    {
+      /* Add the "this" parameter.  */
+      this_parm = build_this_parm (fn, fn_type, this_quals);
+      DECL_CHAIN (this_parm) = DECL_ARGUMENTS (fn);
+      DECL_ARGUMENTS (fn) = this_parm;
+
+      grokclassfn (type, fn, kind == sfk_destructor ? DTOR_FLAG : NO_SPECIAL);
+    }
+
   DECL_IN_AGGR_P (fn) = 1;
   DECL_ARTIFICIAL (fn) = 1;
   DECL_DEFAULTED_FN (fn) = 1;