Allow deduction guides to look into primary template.

	* cp-tree.h (struct saved_scope): Add deduction_guide_type.
	(struct cp_decl_specifier_seq): Add constructor_p.
	* parser.c (cp_parser_decl_specifier_seq): Set constructor_p.
	(cp_parser_init_declarator): Check it.  Set ctor_dtor_or_conv_p.
	Clear deduction_guide_type.  Don't handle deduction guide names.
	(cp_parser_declarator): Don't clear ctor_dtor_or_conv_p.
	(cp_parser_direct_declarator): Likewise.  Handle deduction guides.
	(cp_parser_member_declaration, cp_parser_cache_defarg)
	(cp_parser_objc_class_ivars): Set ctor_dtor_or_conv_p.
	* pt.c (tsubst_copy, tsubst_copy_and_build): Revert last change.
	(build_deduction_guide): Set deduction_guide_type.
	(dependent_scope_p): Check deduction_guide_type.
	* search.c (lookup_member): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@245858 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 90 insertions, 50 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 04ae0de3260..7b68b139599 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,20 @@
+2017-03-02  Jason Merrill  <jason@redhat.com>
+
+	Allow deduction guides to look into primary template.
+	* cp-tree.h (struct saved_scope): Add deduction_guide_type.
+	(struct cp_decl_specifier_seq): Add constructor_p.
+	* parser.c (cp_parser_decl_specifier_seq): Set constructor_p.
+	(cp_parser_init_declarator): Check it.  Set ctor_dtor_or_conv_p.
+	Clear deduction_guide_type.  Don't handle deduction guide names.
+	(cp_parser_declarator): Don't clear ctor_dtor_or_conv_p.
+	(cp_parser_direct_declarator): Likewise.  Handle deduction guides.
+	(cp_parser_member_declaration, cp_parser_cache_defarg)
+	(cp_parser_objc_class_ivars): Set ctor_dtor_or_conv_p.
+	* pt.c (tsubst_copy, tsubst_copy_and_build): Revert last change.
+	(build_deduction_guide): Set deduction_guide_type.
+	(dependent_scope_p): Check deduction_guide_type.
+	* search.c (lookup_member): Likewise.
+
 2017-03-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/79782
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f53f7442bc9..31edc5f175b 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1272,6 +1272,7 @@ struct GTY(()) saved_scope {
   vec<tree, va_gc> *lang_base;
   tree lang_name;
   tree template_parms;
+  tree deduction_guide_type;
   cp_binding_level *x_previous_class_level;
   tree x_saved_tree;
 
@@ -5422,6 +5423,9 @@ struct cp_decl_specifier_seq {
   BOOL_BITFIELD gnu_thread_keyword_p : 1;
   /* True iff the type is a decltype.  */
   BOOL_BITFIELD decltype_p : 1;
+  /* True iff the declaration declares a constructor or C++17 deduction
+     guide.  */
+  BOOL_BITFIELD constructor_p : 1;
 };
 
 /* The various kinds of declarators.  */
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index e6848701150..fbe864f685a 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -13313,6 +13313,8 @@ cp_parser_decl_specifier_seq (cp_parser* parser,
 	   && constructor_possible_p
 	   && (cp_parser_constructor_declarator_p
 	       (parser, decl_spec_seq_has_spec_p (decl_specs, ds_friend))));
+      if (constructor_p)
+	decl_specs->constructor_p = true;
 
       /* If we don't have a DECL_SPEC yet, then we must be looking at
 	 a type-specifier.  */
@@ -19010,7 +19012,7 @@ cp_parser_init_declarator (cp_parser* parser,
   enum cpp_ttype initialization_kind;
   bool is_direct_init = false;
   bool is_non_constant_init;
-  int ctor_dtor_or_conv_p;
+  int ctor_dtor_or_conv_p = decl_specifiers->constructor_p ? -1 : 0;
   bool friend_p = cp_parser_friend_p (decl_specifiers);
   tree pushed_scope = NULL_TREE;
   bool range_for_decl_p = false;
@@ -19048,6 +19050,9 @@ cp_parser_init_declarator (cp_parser* parser,
 
   parser->default_arg_ok_p = saved_default_arg_ok_p;
 
+  if (cxx_dialect >= cxx1z)
+    scope_chain->deduction_guide_type = NULL_TREE;
+
   /* If the DECLARATOR was erroneous, there's no need to go
      further.  */
   if (declarator == cp_error_declarator)
@@ -19095,25 +19100,6 @@ cp_parser_init_declarator (cp_parser* parser,
 
   if (function_declarator_p (declarator))
     {
-      /* Handle C++17 deduction guides.  */
-      if (!decl_specifiers->type
-	  && ctor_dtor_or_conv_p <= 0
-	  && cxx_dialect >= cxx1z)
-	{
-	  cp_declarator *id = get_id_declarator (declarator);
-	  tree name = id->u.id.unqualified_name;
-	  parser->scope = id->u.id.qualifying_scope;
-	  tree tmpl = cp_parser_lookup_name_simple (parser, name, id->id_loc);
-	  if (tmpl
-	      && (DECL_CLASS_TEMPLATE_P (tmpl)
-		  || DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
-	    {
-	      id->u.id.unqualified_name = dguide_name (tmpl);
-	      id->u.id.sfk = sfk_deduction_guide;
-	      ctor_dtor_or_conv_p = 1;
-	    }
-	}
-
       /* Check to see if the token indicates the start of a
 	 function-definition.  */
       if (cp_parser_token_starts_function_definition_p (token))
@@ -19432,8 +19418,10 @@ cp_parser_init_declarator (cp_parser* parser,
 
    If CTOR_DTOR_OR_CONV_P is not NULL, *CTOR_DTOR_OR_CONV_P is used to
    detect constructors, destructors, deduction guides, or conversion operators.
-   It is set to -1 if the declarator is a name, and +1 if it is a
-   function. Otherwise it is set to zero. Usually you just want to
+   The caller should set it before the call, to -1 if parsing the
+   decl-specifier-seq determined that we're declaring a constructor or
+   deduction guide, or 0 otherwise.  This function sets it to -1 if the
+   declarator is a name, and +1 if it is a function. Usually you just want to
    test for >0, but internally the negative value is used.
 
    (The reason for CTOR_DTOR_OR_CONV_P is that a declaration must have
@@ -19464,11 +19452,6 @@ cp_parser_declarator (cp_parser* parser,
   tree class_type;
   tree gnu_attributes = NULL_TREE, std_attributes = NULL_TREE;
 
-  /* Assume this is not a constructor, destructor, or type-conversion
-     operator.  */
-  if (ctor_dtor_or_conv_p)
-    *ctor_dtor_or_conv_p = 0;
-
   if (cp_parser_allow_gnu_extensions_p (parser))
     gnu_attributes = cp_parser_gnu_attributes_opt (parser);
 
@@ -19766,9 +19749,6 @@ cp_parser_direct_declarator (cp_parser* parser,
 	  /* Parse an array-declarator.  */
 	  tree bounds, attrs;
 
-	  if (ctor_dtor_or_conv_p)
-	    *ctor_dtor_or_conv_p = 0;
-
 	  first = false;
 	  parser->default_arg_ok_p = false;
 	  parser->in_declarator_p = true;
@@ -20023,6 +20003,34 @@ cp_parser_direct_declarator (cp_parser* parser,
 		      *ctor_dtor_or_conv_p = -1;
 		  }
 	      }
+
+	    if (cxx_dialect >= cxx1z
+		&& sfk == sfk_none
+		&& ctor_dtor_or_conv_p
+		&& *ctor_dtor_or_conv_p == -1)
+	      {
+		/* If *ctor_dtor_or_conv_p is set and we aren't declaring a
+		   constructor, we must be declaring a deduction guide.  */
+		tree tmpl;
+		if (qualifying_scope)
+		  tmpl = (lookup_qualified_name
+			  (qualifying_scope, unqualified_name,
+			   /*prefer_type*/false, /*complain*/true));
+		else
+		  tmpl = lookup_name (unqualified_name);
+		if (tmpl
+		    && (DECL_CLASS_TEMPLATE_P (tmpl)
+			|| DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
+		  {
+		    unqualified_name = dguide_name (tmpl);
+		    scope_chain->deduction_guide_type
+		      = TREE_TYPE (unqualified_name);
+		    sfk = sfk_deduction_guide;
+		  }
+		else
+		  gcc_checking_assert (false);
+	      }
+
 	    declarator = make_id_declarator (qualifying_scope,
 					     unqualified_name,
 					     sfk);
@@ -23251,7 +23259,7 @@ cp_parser_member_declaration (cp_parser* parser)
 	      cp_declarator *declarator;
 	      tree initializer;
 	      tree asm_specification;
-	      int ctor_dtor_or_conv_p;
+	      int ctor_dtor_or_conv_p = decl_specifiers.constructor_p ? -1 : 0;
 
 	      /* Parse the declarator.  */
 	      declarator
@@ -28334,7 +28342,7 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
 		     declarator.  */
 		  do
 		    {
-		      int ctor_dtor_or_conv_p;
+		      int ctor_dtor_or_conv_p = 0;
 		      cp_lexer_consume_token (parser->lexer);
 		      cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
 					    &ctor_dtor_or_conv_p,
@@ -29655,7 +29663,7 @@ cp_parser_objc_class_ivars (cp_parser* parser)
 	{
 	  tree width = NULL_TREE, attributes, first_attribute, decl;
 	  cp_declarator *declarator = NULL;
-	  int ctor_dtor_or_conv_p;
+	  int ctor_dtor_or_conv_p = 0;
 
 	  /* Check for a (possibly unnamed) bitfield declaration.  */
 	  token = cp_lexer_peek_token (parser->lexer);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 8144ca66a01..3b320fc2b48 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14641,15 +14641,6 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	     have to substitute this with one having context `D<int>'.  */
 
 	  tree context = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
-	  if (dependent_scope_p (context))
-	    {
-	      /* When rewriting a constructor into a deduction guide, a
-		 non-dependent name can become dependent, so memtmpl<args>
-		 becomes context::template memtmpl<args>.  */
-	      tree type = tsubst (TREE_TYPE (t), args, complain, in_decl);
-	      return build_qualified_name (type, context, DECL_NAME (t),
-					   /*template*/true);
-	    }
 	  return lookup_field (context, DECL_NAME(t), 0, false);
 	}
       else
@@ -16633,14 +16624,6 @@ tsubst_copy_and_build (tree t,
 	if (targs == error_mark_node)
 	  return error_mark_node;
 
-	if (TREE_CODE (templ) == SCOPE_REF)
-	  {
-	    tree name = TREE_OPERAND (templ, 1);
-	    tree tid = lookup_template_function (name, targs);
-	    TREE_OPERAND (templ, 1) = tid;
-	    return templ;
-	  }
-
 	if (variable_template_p (templ))
 	  RETURN (lookup_and_finish_template_variable (templ, targs, complain));
 
@@ -23476,6 +23459,9 @@ bool
 dependent_scope_p (tree scope)
 {
   return (scope && TYPE_P (scope) && dependent_type_p (scope)
+	  && !(cxx_dialect >= cxx1z
+	       && scope_chain->deduction_guide_type
+	       && same_type_p (scope, scope_chain->deduction_guide_type))
 	  && !currently_open_class (scope));
 }
 
@@ -24997,6 +24983,7 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
       if (outer_args)
 	ctor = tsubst (ctor, outer_args, complain, ctor);
       type = DECL_CONTEXT (ctor);
+      scope_chain->deduction_guide_type = type;
       tree fn_tmpl;
       if (TREE_CODE (ctor) == TEMPLATE_DECL)
 	{
@@ -25089,6 +25076,7 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
 	  current_template_parms = save_parms;
 	  --processing_template_decl;
 	}
+      scope_chain->deduction_guide_type = NULL_TREE;
     }
 
   if (!memtmpl)
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 09c1b4e6456..6eb41243814 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -1279,6 +1279,13 @@ lookup_member (tree xbasetype, tree name, int protect, bool want_type,
     if (tree t = currently_open_class (type))
       type = t;
 
+  /* Declaration of a deduction guide can look inside the primary class
+     template; replace a compatible type with the real one.  */
+  if (cxx_dialect >= cxx1z
+      && scope_chain->deduction_guide_type
+      && same_type_p (type, scope_chain->deduction_guide_type))
+    type = scope_chain->deduction_guide_type;
+
   if (!basetype_path)
     basetype_path = TYPE_BINFO (type);
 
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
new file mode 100644
index 00000000000..ee21d147fd6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
@@ -0,0 +1,16 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A
+{
+  using value_t = T;
+  A(value_t);
+};
+
+template <class T>
+A(typename A<T>::value_t) -> A<double>;
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+
+A a(42);
+same<decltype(a),A<double>> s1;