PR c++/90572 - wrong disambiguation in friend declaration.

	* parser.c (cp_parser_constructor_declarator_p): Don't allow missing
	typename for friend declarations.

	* g++.dg/cpp2a/typename16.C: New test.
	* g++.dg/parse/friend13.C: New test.

From-SVN: r271620

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 7548b65589c028adeb187590c6771f05976b8b0a..40c920280dc20c3e42067e5d7571fb85c3102762 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2019-05-25  Marek Polacek  <polacek@redhat.com>
+
+       Backported from mainline
+       2019-05-25  Marek Polacek  <polacek@redhat.com>
+
+       PR c++/90572 - wrong disambiguation in friend declaration.
+       * parser.c (cp_parser_constructor_declarator_p): Don't allow missing
+       typename for friend declarations.
+
 2019-05-20  Jonathan Wakely  <jwakely@redhat.com>
 
        Backported from mainline

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 3d908916ae3f7d4c1daaafc3b4858b4d9a94a74a..a7218e752b1670407c7172f1196788ab4ce92e33 100644 (file)
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -27629,9 +27629,19 @@ cp_parser_constructor_declarator_p (cp_parser *parser, cp_parser_flags flags,
          parser->num_template_parameter_lists = 0;
 
          /* Look for the type-specifier.  It's not optional, but its typename
-            might be.  */
+            might be.  Unless this is a friend declaration; we don't want to
+            treat
+
+              friend S (T::fn)(int);
+
+            as a constructor, but with P0634, we might assume a type when
+            looking for the type-specifier.  It is actually a function named
+            `T::fn' that takes one parameter (of type `int') and returns a
+            value of type `S'.  Constructors can be friends, but they must
+            use a qualified name.  */
          cp_parser_type_specifier (parser,
-                                   (flags & ~CP_PARSER_FLAGS_OPTIONAL),
+                                   (friend_p ? CP_PARSER_FLAGS_NONE
+                                    : (flags & ~CP_PARSER_FLAGS_OPTIONAL)),
                                    /*decl_specs=*/NULL,
                                    /*is_declarator=*/true,
                                    /*declares_class_or_enum=*/NULL,

diff --git a/gcc/testsuite/g++.dg/cpp2a/typename16.C b/gcc/testsuite/g++.dg/cpp2a/typename16.C
new file mode 100644 (file)
index 0000000..7f4242a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/typename16.C
@@ -0,0 +1,11 @@
+// PR c++/90572
+// { dg-do compile { target c++2a } }
+
+struct X { X(int); };
+
+template<typename T> struct S {
+  friend X::X(T::t);
+};
+
+struct W { using t = int; };
+S<W> s;

diff --git a/gcc/testsuite/g++.dg/parse/friend13.C b/gcc/testsuite/g++.dg/parse/friend13.C
new file mode 100644 (file)
index 0000000..d716247
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/friend13.C
@@ -0,0 +1,16 @@
+// PR c++/90572
+
+template <typename T> struct C {
+  friend C(T::fn)();
+  friend C(T::fn)(int);
+  friend C(T::fn)(int, int);
+};
+
+struct X { };
+
+template<typename T>
+struct B {
+  friend X(T::fn)();
+  friend X(T::fn)(int);
+  friend X(T::fn)(int, int);
+};