Hi,

another old issue, which should be also relatively easy to fix. The problem is clear, for:

struct S {
  struct T{};
  friend void S(T);
};

cp_parser_direct_declarator sees a name which matches that of a kosher constructor and sets sfk_constructor. Then things go quickly wrong because a constructor cannot have a return type specification, thus check_special_function_return_type, called by grokdeclarator, complains.

I tried various ideas (eg, I'm also attaching an alternate approach passing down the friend information from cp_parser_member_declaration to cp_parser_direct_declarator), but, all in all, I propose to adjust things in grodeclarator itself. Tested x86_64-linux.

Thanks!
Paolo.

//////////////////////////
Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 211389)
+++ cp/decl.c   (working copy)
@@ -8774,7 +8774,8 @@ grokdeclarator (const cp_declarator *declarator,
   tree type = NULL_TREE;
   int longlong = 0;
   int explicit_int128 = 0;
-  int virtualp, explicitp, friendp, inlinep, staticp;
+  int virtualp, explicitp, inlinep, staticp;
+  int friendp = decl_spec_seq_has_spec_p (declspecs, ds_friend);
   int explicit_int = 0;
   int explicit_char = 0;
   int defaulted_int = 0;
@@ -8880,6 +8881,26 @@ grokdeclarator (const cp_declarator *declarator,
              sfk = id_declarator->declarator->u.id.sfk;
              if (sfk == sfk_destructor)
                flags = DTOR_FLAG;
+             else if (sfk == sfk_constructor
+                      && friendp
+                      && declspecs->type)
+               /* cp_parser_direct_declarator doesn't know about the
+                  'friend' specifier and returns sfk_constructor for
+
+                  struct S {
+                    struct T{};
+                    friend void S(T);
+                  };
+
+                  thus adjust it here (c++/19200).  Note: the return
+                  type is checked because with -fpermissive we still
+                  want to accept
+
+                  struct S {
+                    struct T{};
+                    friend S::S(T);
+                  };  */
+               sfk = sfk_none;
            }
          break;
 
@@ -9378,7 +9399,6 @@ grokdeclarator (const cp_declarator *declarator,
       storage_class = sc_none;
       staticp = 0;
     }
-  friendp = decl_spec_seq_has_spec_p (declspecs, ds_friend);
 
   /* Issue errors about use of storage classes for parameters.  */
   if (decl_context == PARM)
Index: testsuite/g++.dg/parse/friend7.C
===================================================================
--- testsuite/g++.dg/parse/friend7.C    (revision 211384)
+++ testsuite/g++.dg/parse/friend7.C    (working copy)
@@ -17,16 +17,16 @@ struct B
 
 struct C
 {
-  friend int C ();             // { dg-error "return type|in friend decl" }
+  friend int C ();
   friend int ~C ();            // { dg-error "return type|in friend decl" }
-  friend int C (const C &);    // { dg-error "return type|in friend decl" }
+  friend int C (const C &);
 };
 
 struct D
 {
-  friend int D () {}           // { dg-error "return type|in friend decl" }
+  friend int D () {}
   friend int ~D () {}          // { dg-error "return type|in friend decl" }
-  friend int D (const D &) {}  // { dg-error "return type|in friend decl" }
+  friend int D (const D &) {}
 };
 
 struct E
Index: testsuite/g++.dg/parse/friend9.C
===================================================================
--- testsuite/g++.dg/parse/friend9.C    (revision 0)
+++ testsuite/g++.dg/parse/friend9.C    (working copy)
@@ -0,0 +1,6 @@
+// PR c++/19200
+
+struct S {
+  struct T{};
+  friend void S(T);
+};
Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 211384)
+++ cp/parser.c (working copy)
@@ -2078,9 +2078,9 @@ static tree cp_parser_decltype
 static tree cp_parser_init_declarator
   (cp_parser *, cp_decl_specifier_seq *, vec<deferred_access_check, va_gc> *, 
bool, bool, int, bool *, tree *);
 static cp_declarator *cp_parser_declarator
-  (cp_parser *, cp_parser_declarator_kind, int *, bool *, bool);
+  (cp_parser *, cp_parser_declarator_kind, int *, bool *, bool, bool);
 static cp_declarator *cp_parser_direct_declarator
-  (cp_parser *, cp_parser_declarator_kind, int *, bool);
+  (cp_parser *, cp_parser_declarator_kind, int *, bool, bool);
 static enum tree_code cp_parser_ptr_operator
   (cp_parser *, tree *, cp_cv_quals *, tree *);
 static cp_cv_quals cp_parser_cv_qualifier_seq_opt
@@ -10014,7 +10014,8 @@ cp_parser_condition (cp_parser* parser)
       declarator = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                                         /*ctor_dtor_or_conv_p=*/NULL,
                                         /*parenthesized_p=*/NULL,
-                                        /*member_p=*/false);
+                                        /*member_p=*/false,
+                                        /*friend_p=*/false);
       /* Parse the attributes.  */
       attributes = cp_parser_attributes_opt (parser);
       /* Parse the asm-specification.  */
@@ -14160,7 +14161,8 @@ cp_parser_explicit_instantiation (cp_parser* parse
        = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                                /*ctor_dtor_or_conv_p=*/NULL,
                                /*parenthesized_p=*/NULL,
-                               /*member_p=*/false);
+                               /*member_p=*/false,
+                               /*friend_p=*/false);
       if (declares_class_or_enum & 2)
        cp_parser_check_for_definition_in_return_type (declarator,
                                                       decl_specifiers.type,
@@ -16570,7 +16572,7 @@ cp_parser_init_declarator (cp_parser* parser,
     = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                            &ctor_dtor_or_conv_p,
                            /*parenthesized_p=*/NULL,
-                           member_p);
+                           member_p, /*friend_p=*/false);
   /* Gather up the deferred checks.  */
   stop_deferring_access_checks ();
 
@@ -16958,14 +16960,17 @@ cp_parser_init_declarator (cp_parser* parser,
    If PARENTHESIZED_P is non-NULL, *PARENTHESIZED_P is set to true iff
    the declarator is a direct-declarator of the form "(...)".
 
-   MEMBER_P is true iff this declarator is a member-declarator.  */
+   MEMBER_P is true iff this declarator is a member-declarator.
 
+   If FRIEND_P is true, the declarator is preceded by the `friend'
+   specifier.  */
+
 static cp_declarator *
 cp_parser_declarator (cp_parser* parser,
                      cp_parser_declarator_kind dcl_kind,
                      int* ctor_dtor_or_conv_p,
                      bool* parenthesized_p,
-                     bool member_p)
+                     bool member_p, bool friend_p)
 {
   cp_declarator *declarator;
   enum tree_code code;
@@ -17005,7 +17010,8 @@ cp_parser_declarator (cp_parser* parser,
       declarator = cp_parser_declarator (parser, dcl_kind,
                                         /*ctor_dtor_or_conv_p=*/NULL,
                                         /*parenthesized_p=*/NULL,
-                                        /*member_p=*/false);
+                                        /*member_p=*/false,
+                                        friend_p);
 
       /* If we are parsing an abstract-declarator, we must handle the
         case where the dependent declarator is absent.  */
@@ -17024,7 +17030,7 @@ cp_parser_declarator (cp_parser* parser,
                                                   CPP_OPEN_PAREN);
       declarator = cp_parser_direct_declarator (parser, dcl_kind,
                                                ctor_dtor_or_conv_p,
-                                               member_p);
+                                               member_p, friend_p);
     }
 
   if (gnu_attributes && declarator && declarator != cp_error_declarator)
@@ -17058,14 +17064,14 @@ cp_parser_declarator (cp_parser* parser,
    we are parsing a direct-declarator.  It is
    CP_PARSER_DECLARATOR_EITHER, if we can accept either - in the case
    of ambiguity we prefer an abstract declarator, as per
-   [dcl.ambig.res].  CTOR_DTOR_OR_CONV_P and MEMBER_P are as for
-   cp_parser_declarator.  */
+   [dcl.ambig.res].  CTOR_DTOR_OR_CONV_P, MEMBER_P, and FRIEND_P are
+   as for cp_parser_declarator.  */
 
 static cp_declarator *
 cp_parser_direct_declarator (cp_parser* parser,
                             cp_parser_declarator_kind dcl_kind,
                             int* ctor_dtor_or_conv_p,
-                            bool member_p)
+                            bool member_p, bool friend_p)
 {
   cp_token *token;
   cp_declarator *declarator = NULL;
@@ -17246,7 +17252,7 @@ cp_parser_direct_declarator (cp_parser* parser,
              declarator
                = cp_parser_declarator (parser, dcl_kind, ctor_dtor_or_conv_p,
                                        /*parenthesized_p=*/NULL,
-                                       member_p);
+                                       member_p, friend_p);
              parser->in_type_id_in_expr_p = saved_in_type_id_in_expr_p;
              first = false;
              /* Expect a `)'.  */
@@ -17492,6 +17498,7 @@ cp_parser_direct_declarator (cp_parser* parser,
                                for an anonymous type, even if the type
                                got a name for linkage purposes.  */
                             !TYPE_WAS_ANONYMOUS (class_type)
+                            && !friend_p
                             && constructor_name_p (unqualified_name,
                                                    class_type))
                      {
@@ -18035,7 +18042,8 @@ cp_parser_type_id_1 (cp_parser* parser, bool is_te
   abstract_declarator
     = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_ABSTRACT, NULL,
                            /*parenthesized_p=*/NULL,
-                           /*member_p=*/false);
+                           /*member_p=*/false,
+                           /*friend_p=*/false);
   /* Check to see if there really was a declarator.  */
   if (!cp_parser_parse_definitely (parser))
     abstract_declarator = NULL;
@@ -18610,7 +18618,8 @@ cp_parser_parameter_declaration (cp_parser *parser
                                         CP_PARSER_DECLARATOR_EITHER,
                                         /*ctor_dtor_or_conv_p=*/NULL,
                                         parenthesized_p,
-                                        /*member_p=*/false);
+                                        /*member_p=*/false,
+                                        /*friend_p=*/false);
       parser->default_arg_ok_p = saved_default_arg_ok_p;
       /* After the declarator, allow more attributes.  */
       decl_specifiers.attributes
@@ -20446,8 +20455,20 @@ cp_parser_member_declaration (cp_parser* parser)
                = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                                        &ctor_dtor_or_conv_p,
                                        /*parenthesized_p=*/NULL,
-                                       /*member_p=*/true);
+                                       /*member_p=*/true,
+                                       friend_p
+                                       /* With -fpermissive we want to accept:
 
+                                          struct S {
+                                            struct T{};
+                                            friend S::S(T);
+                                          };
+
+                                          thus also check the return type
+                                          to do the right thing later in
+                                          cp_parser_direct_declarator.  */
+                                       && decl_specifiers.type);
+
              /* If something went wrong parsing the declarator, make sure
                 that we at least consume some tokens.  */
              if (declarator == cp_error_declarator)
@@ -21274,7 +21295,8 @@ cp_parser_exception_declaration (cp_parser* parser
     declarator = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_EITHER,
                                       /*ctor_dtor_or_conv_p=*/NULL,
                                       /*parenthesized_p=*/NULL,
-                                      /*member_p=*/false);
+                                      /*member_p=*/false,
+                                      /*friend_p=*/false);
 
   /* Restore the saved message.  */
   parser->type_definition_forbidden_message = saved_message;
@@ -24820,7 +24842,8 @@ cp_parser_cache_defarg (cp_parser *parser, bool ns
                  cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                                        &ctor_dtor_or_conv_p,
                                        /*parenthesized_p=*/NULL,
-                                       /*member_p=*/true);
+                                       /*member_p=*/true,
+                                       /*friend_p=*/false);
                }
              else
                {
@@ -26106,7 +26129,8 @@ cp_parser_objc_class_ivars (cp_parser* parser)
                = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
                                        &ctor_dtor_or_conv_p,
                                        /*parenthesized_p=*/NULL,
-                                       /*member_p=*/false);
+                                       /*member_p=*/false,
+                                       /*friend_p=*/false);
            }
 
          /* Look for attributes that apply to the ivar.  */
@@ -26657,7 +26681,7 @@ cp_parser_objc_struct_declaration (cp_parser *pars
 
       /* Parse the declarator.  */
       declarator = cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
-                                        NULL, NULL, false);
+                                        NULL, NULL, false, false);
 
       /* Look for attributes that apply to the ivar.  */
       attributes = cp_parser_attributes_opt (parser);
@@ -29170,7 +29194,8 @@ cp_parser_omp_for_loop_init (cp_parser *parser,
                                         CP_PARSER_DECLARATOR_NAMED,
                                         /*ctor_dtor_or_conv_p=*/NULL,
                                         /*parenthesized_p=*/NULL,
-                                        /*member_p=*/false);
+                                        /*member_p=*/false,
+                                        /*friend_p=*/false);
       attributes = cp_parser_attributes_opt (parser);
       asm_specification = cp_parser_asm_specification_opt (parser);
 

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