Implement UDL changes from P0732R2.

Implementing the UDL changes was pretty straightforward; I simplified
cp_parser_userdef_string_literal using the releasing_vec type from mangle.c.

While looking at this, I realized that the string UDL template taking a
character pack that we implemented for C++14 didn't actually make it into
C++14, so I've added a pedwarn for it and no longer suggest it in the
diagnostic about an invalid UDL template.

	* cp-tree.h (struct releasing_vec): Move from mangle.c.
	Add get_ref method.
	* parser.c (cp_parser_userdef_string_literal): Use it.  Handle
	passing the string to a single template parameter of class type.
	(cp_parser_template_declaration_after_parameters): Allow it.
	Pedwarn about the character pack template that was proposed but not
	accepted for C++14, and don't suggest it.

From-SVN: r265790

12 files changed, 121 insertions, 69 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 95149b1..b0dc668 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,14 @@
 2018-11-04  Jason Merrill  <jason@redhat.com>
 
+	Implement UDL changes from P0732R2.
+	* cp-tree.h (struct releasing_vec): Move from mangle.c.
+	Add get_ref method.
+	* parser.c (cp_parser_userdef_string_literal): Use it.  Handle
+	passing the string to a single template parameter of class type.
+	(cp_parser_template_declaration_after_parameters): Allow it.
+	Pedwarn about the character pack template that was proposed but not
+	accepted for C++14, and don't suggest it.
+
 	Implement P0732R2, class types in non-type template parameters.
 	* error.c (dump_simple_decl): Look through a template parm object.
 	* mangle.c (write_template_arg): Likewise.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 61b431e..a895d00 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -871,6 +871,34 @@ struct named_decl_hash : ggc_remove <tree>
   static void mark_deleted (value_type) { gcc_unreachable (); }
 };
 
+/* Simplified unique_ptr clone to release a tree vec on exit.  */
+
+struct releasing_vec
+{
+  typedef vec<tree, va_gc> vec_t;
+
+  releasing_vec (vec_t *v): v(v) { }
+  releasing_vec (): v(make_tree_vector ()) { }
+
+  /* Copy ops are deliberately declared but not defined,
+     copies must always be elided.  */
+  releasing_vec (const releasing_vec &);
+  releasing_vec &operator= (const releasing_vec &);
+
+  vec_t &operator* () const { return *v; }
+  vec_t *operator-> () const { return v; }
+  vec_t *get() const { return v; }
+  operator vec_t *() const { return v; }
+  tree& operator[] (unsigned i) const { return (*v)[i]; }
+
+  /* Necessary for use with vec** and vec*& interfaces.  */
+  vec_t *&get_ref () { return v; }
+
+  ~releasing_vec() { release_tree_vector (v); }
+private:
+  vec_t *v;
+};
+
 struct GTY(()) tree_template_decl {
   struct tree_decl_common common;
   tree arguments;
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 1b32301..b9d8ee2 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -1545,30 +1545,6 @@ write_abi_tags (tree tags)
   release_tree_vector (vec);
 }
 
-/* Simplified unique_ptr clone to release a tree vec on exit.  */
-
-struct releasing_vec
-{
-  typedef vec<tree, va_gc> vec_t;
-
-  releasing_vec (vec_t *v): v(v) { }
-  releasing_vec (): v(make_tree_vector ()) { }
-
-  /* Copy constructor is deliberately declared but not defined,
-     copies must always be elided.  */
-  releasing_vec (const releasing_vec &);
-
-  vec_t &operator* () const { return *v; }
-  vec_t *operator-> () const { return v; }
-  vec_t *get () const { return v; }
-  operator vec_t *() const { return v; }
-  tree& operator[] (unsigned i) const { return (*v)[i]; }
-
-  ~releasing_vec() { release_tree_vector (v); }
-private:
-  vec_t *v;
-};
-
 /* True iff the TREE_LISTS T1 and T2 of ABI tags are equivalent.  */
 
 static bool
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 5ea8e8c..30a4766 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -4565,40 +4565,47 @@ cp_parser_userdef_string_literal (tree literal)
   tree value = USERDEF_LITERAL_VALUE (literal);
   int len = TREE_STRING_LENGTH (value)
 	/ TREE_INT_CST_LOW (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (value)))) - 1;
-  tree decl, result;
-  vec<tree, va_gc> *args;
+  tree decl;
 
   /* Build up a call to the user-defined operator.  */
   /* Lookup the name we got back from the id-expression.  */
-  args = make_tree_vector ();
+  releasing_vec rargs;
+  vec<tree, va_gc> *&args = rargs.get_ref();
   vec_safe_push (args, value);
   vec_safe_push (args, build_int_cst (size_type_node, len));
   decl = lookup_literal_operator (name, args);
 
   if (decl && decl != error_mark_node)
-    {
-      result = finish_call_expr (decl, &args, false, true,
-				 tf_warning_or_error);
-      release_tree_vector (args);
-      return result;
-    }
-  release_tree_vector (args);
+    return finish_call_expr (decl, &args, false, true,
+			     tf_warning_or_error);
 
-  /* Look for a template function with typename parameter CharT
-     and parameter pack CharT...  Call the function with
-     template parameter characters representing the string.  */
-  args = make_tree_vector ();
+  /* Look for a suitable template function, either (C++20) with a single
+     parameter of class type, or (N3599) with typename parameter CharT and
+     parameter pack CharT...  */
+  args->truncate (0);
   decl = lookup_literal_operator (name, args);
   if (decl && decl != error_mark_node)
     {
-      tree tmpl_args = make_string_pack (value);
+      /* Use resolve_nondeduced_context to try to choose one form of template
+	 or the other.  */
+      tree tmpl_args = make_tree_vec (1);
+      TREE_VEC_ELT (tmpl_args, 0) = value;
       decl = lookup_template_function (decl, tmpl_args);
-      result = finish_call_expr (decl, &args, false, true,
-				 tf_warning_or_error);
-      release_tree_vector (args);
-      return result;
+      tree res = resolve_nondeduced_context (decl, tf_none);
+      if (DECL_P (res))
+	decl = res;
+      else
+	{
+	  TREE_OPERAND (decl, 1) = make_string_pack (value);
+	  res = resolve_nondeduced_context (decl, tf_none);
+	  if (DECL_P (res))
+	    decl = res;
+	}
+      if (!DECL_P (decl) && cxx_dialect > cxx17)
+	TREE_OPERAND (decl, 1) = tmpl_args;
+      return finish_call_expr (decl, &args, false, true,
+			       tf_warning_or_error);
     }
-  release_tree_vector (args);
 
   error ("unable to find string literal operator %qD with %qT, %qT arguments",
 	 name, TREE_TYPE (value), size_type_node);
@@ -27222,8 +27229,12 @@ cp_parser_template_declaration_after_parameters (cp_parser* parser,
 	    {
 	      tree parm_list = TREE_VEC_ELT (parameter_list, 0);
 	      tree parm = INNERMOST_TEMPLATE_PARMS (parm_list);
-	      if (TREE_TYPE (parm) != char_type_node
-		  || !TEMPLATE_PARM_PARAMETER_PACK (DECL_INITIAL (parm)))
+	      if (CLASS_TYPE_P (TREE_TYPE (parm)))
+		/* OK, C++20 string literal operator template.  We don't need
+		   to warn in lower dialects here because we will have already
+		   warned about the template parameter.  */;
+	      else if (TREE_TYPE (parm) != char_type_node
+		       || !TEMPLATE_PARM_PARAMETER_PACK (DECL_INITIAL (parm)))
 		ok = false;
 	    }
 	  else if (num_parms == 2 && cxx_dialect >= cxx14)
@@ -27236,20 +27247,25 @@ cp_parser_template_declaration_after_parameters (cp_parser* parser,
 		  || TREE_TYPE (parm) != TREE_TYPE (type)
 		  || !TEMPLATE_PARM_PARAMETER_PACK (DECL_INITIAL (parm)))
 		ok = false;
+	      else
+		/* http://cplusplus.github.io/EWG/ewg-active.html#66  */
+		pedwarn (DECL_SOURCE_LOCATION (decl), OPT_Wpedantic,
+			 "ISO C++ did not adopt string literal operator templa"
+			 "tes taking an argument pack of characters");
 	    }
 	  else
 	    ok = false;
 	}
       if (!ok)
 	{
-	  if (cxx_dialect >= cxx14)
-	    error ("literal operator template %qD has invalid parameter list."
-		   "  Expected non-type template argument pack <char...>"
-		   " or <typename CharT, CharT...>",
+	  if (cxx_dialect > cxx17)
+	    error ("literal operator template %qD has invalid parameter list;"
+		   "  Expected non-type template parameter pack <char...> "
+		   "  or single non-type parameter of class type",
 		   decl);
 	  else
 	    error ("literal operator template %qD has invalid parameter list."
-		   "  Expected non-type template argument pack <char...>",
+		   "  Expected non-type template parameter pack <char...>",
 		   decl);
 	}
     }
diff --git a/gcc/testsuite/g++.dg/cpp0x/udlit-overflow.C b/gcc/testsuite/g++.dg/cpp0x/udlit-overflow.C
index 057978c..1b9888b 100644
--- a/gcc/testsuite/g++.dg/cpp0x/udlit-overflow.C
+++ b/gcc/testsuite/g++.dg/cpp0x/udlit-overflow.C
@@ -1,19 +1,19 @@
 // { dg-do compile { target c++11 } }
-// PR c++/52654

-

-int

-operator"" _w(const char*)

-{ return 0; }

-

-template<char...>

-  int

-  operator"" _tw()

-  { return 0; }

-

-int i = 12345678901234567890123456789012345678901234567890_w;

-int j = 12345678901234567890123456789.012345678901234567890e+1234567890_w;

-int k = 12345678901234567890123456789.012345678901234567890e-1234567890_w;

-

-int ti = 12345678901234567890123456789012345678901234567890_tw;

-int tj = 12345678901234567890123456789.012345678901234567890e+1234567890_tw;

-int tk = 12345678901234567890123456789.012345678901234567890e-1234567890_tw;

+// PR c++/52654
+
+int
+operator"" _w(const char*)
+{ return 0; }
+
+template<char...>
+  int
+  operator"" _tw()
+  { return 0; }
+
+int i = 12345678901234567890123456789012345678901234567890_w;
+int j = 12345678901234567890123456789.012345678901234567890e+1234567890_w;
+int k = 12345678901234567890123456789.012345678901234567890e-1234567890_w;
+
+int ti = 12345678901234567890123456789012345678901234567890_tw;
+int tj = 12345678901234567890123456789.012345678901234567890e+1234567890_tw;
+int tk = 12345678901234567890123456789.012345678901234567890e-1234567890_tw;
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr58708.C b/gcc/testsuite/g++.dg/cpp1y/pr58708.C
index b46e54b..f1fc3b4 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr58708.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr58708.C
@@ -1,4 +1,5 @@
 // { dg-do run { target c++14 } }
+// { dg-options -w }
 
 template<typename, typename>
   struct is_same
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr59867.C b/gcc/testsuite/g++.dg/cpp1y/pr59867.C
index 2c4f1d0..ee468aa 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr59867.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr59867.C
@@ -1,5 +1,6 @@
 // PR c++/59867
 // { dg-do compile { target c++14 } }
+// { dg-options -w }
 
 using namespace std;
 
diff --git a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-sfinae.C b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-sfinae.C
index a9c577f..b523858 100644
--- a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-sfinae.C
+++ b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-sfinae.C
@@ -1,4 +1,5 @@
 // { dg-do run { target c++14 } }
+// { dg-options -w }
 
 #include <cassert>
 
diff --git a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-vs-std-literal-operator.C b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-vs-std-literal-operator.C
index 6e3ffe4..c5a67c9 100644
--- a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-vs-std-literal-operator.C
+++ b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template-vs-std-literal-operator.C
@@ -1,4 +1,5 @@
 // { dg-do run { target c++14 } }
+// { dg-options -w }
 
 #include <cassert>
 
diff --git a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template.C b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template.C
index 989b9ba..6b7b5ec 100644
--- a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template.C
+++ b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template.C
@@ -1,4 +1,5 @@
 // { dg-do compile { target c++14 } }
+// { dg-options -w }
 
 template<typename CharT, CharT... String>
   int
diff --git a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template2.C b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template2.C
index 06c1326..d3c4c67 100644
--- a/gcc/testsuite/g++.dg/cpp1y/udlit-char-template2.C
+++ b/gcc/testsuite/g++.dg/cpp1y/udlit-char-template2.C
@@ -1,5 +1,6 @@
 // PR c++/85864
 // { dg-do compile { target c++14 } }
+// { dg-options -w }
 
 template<class T, T... S> struct String_template {};
 
diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class6.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class6.C
new file mode 100644
index 0000000..246fab6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class6.C
@@ -0,0 +1,17 @@
+// { dg-do compile { target c++2a } }
+
+struct A {
+  char ar[10];
+  constexpr A (const char *p) : ar()
+  {
+    for (int i = 0; i < 10; ++i)
+      if ((ar[i] = p[i]) == 0)
+	break;
+  }
+  // auto operator<=> (const A&) = default;
+};
+
+template <A a> constexpr A operator "" _sh() { return a; }
+
+constexpr auto a = "foo"_sh;
+static_assert (a.ar[0] == 'f');