c++: using macros around user types breaks when they include comma

We may generate code such as

    basic_symbol (typename Base::kind_type t, YY_RVREF (std::pair<int,int>) v);

which, of course, breaks, because YY_RVREF sees two arguments.  Let's
not play tricks with _VA_ARGS__, I'm unsure about it portability.
Anyway, I plan to change more things in this area.

Reported by Sébastien Villemot.
http://lists.gnu.org/archive/html/bug-bison/2018-11/msg00014.html

* data/variant.hh (b4_basic_symbol_constructor_declare)
(b4_basic_symbol_constructor_define): Don't use macro on user types.
* tests/types.at: Check that we support pairs.

THANKS

@@ -151,6 +151,7 @@ Roland Levillain          roland@lrde.epita.fr
 Satya Kiran Popuri        satyakiran@gmail.com
 Sebastian Setzer          sebastian.setzer.ext@siemens.com
 Sebastien Fricker         sebastien.fricker@gmail.com
+Sébastien Villemot        sebastien@debian.org
 Sergei Steshenko          sergstesh@yahoo.com
 Shura                     debil_urod@ngs.ru
 Simon Sobisch             simonsobisch@web.de

data/variant.hh

@@ -379,26 +379,44 @@ b4_join(b4_symbol_if([$1], [has_type],
 # -----------------------------------
 # Generate a constructor declaration for basic_symbol from given type.
 m4_define([b4_basic_symbol_constructor_declare],
-[[      basic_symbol (]b4_join(
+[[# if 201103L <= YY_CPLUSPLUS
+      basic_symbol (]b4_join(
           [typename Base::kind_type t],
-          b4_symbol_if([$1], [has_type], [YY_RVREF (b4_symbol([$1], [type])) v]),
+          b4_symbol_if([$1], [has_type], [b4_symbol([$1], [type])&& v]),
-          b4_locations_if([YY_RVREF (location_type) l]))[);
+          b4_locations_if([location_type&& l]))[);
+#else
+      basic_symbol (]b4_join(
+          [typename Base::kind_type t],
+          b4_symbol_if([$1], [has_type], [const b4_symbol([$1], [type])& v]),
+          b4_locations_if([const location_type& l]))[);
+#endif
 ]])
 
 # b4_basic_symbol_constructor_define
 # ----------------------------------
 # Generate a constructor implementation for basic_symbol from given type.
 m4_define([b4_basic_symbol_constructor_define],
-[[  template <typename Base>
+[[# if 201103L <= YY_CPLUSPLUS
+  template <typename Base>
   ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
           [typename Base::kind_type t],
-          b4_symbol_if([$1], [has_type], [YY_RVREF (b4_symbol([$1], [type])) v]),
+          b4_symbol_if([$1], [has_type], [b4_symbol([$1], [type])&& v]),
-          b4_locations_if([YY_RVREF (location_type) l]))[)
+          b4_locations_if([location_type&& l]))[)
     : Base (t)]b4_symbol_if([$1], [has_type], [
-    , value (YY_MOVE (v))])[]b4_locations_if([
+    , value (std::move (v))])[]b4_locations_if([
-    , location (YY_MOVE (l))])[
+    , location (std::move (l))])[
   {}
-
+#else
+  template <typename Base>
+  ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
+          [typename Base::kind_type t],
+          b4_symbol_if([$1], [has_type], [const b4_symbol([$1], [type])& v]),
+          b4_locations_if([const location_type& l]))[)
+    : Base (t)]b4_symbol_if([$1], [has_type], [
+    , value (v)])[]b4_locations_if([
+    , location (l)])[
+  {}
+#endif
 ]])
 
 # b4_symbol_constructor_define

tests/types.at

@@ -270,6 +270,24 @@ m4_foreach([b4_skel], [[yacc.c], [glr.c], [lalr1.cc], [glr.cc]],
                AT_VAL.build<std::string> ("two");],
             [10, two])
 
+    # Test a regression where we passed user types (we can include
+    # commas) to a CPP macro.
+    AT_TEST([%skeleton "]b4_skel["
+             %define api.value.type variant],
+            [%token <std::pair<int, int>> '1';
+             %token <std::pair<std::string, std::string>> '2';],
+            ['1' '2'
+              {
+                std::cout << $1.first << ':' << $1.second << ", "
+                          << $2.first << ':' << $2.second << '\n';
+              }],
+            ["12"],
+            [if (res == '1')
+               AT_VAL.build (std::make_pair (10, 11));
+             else if (res == '2')
+               AT_VAL.build (std::make_pair<std::string, std::string> ("two", "deux"));],
+            [10:11, two:deux])
+
     # Move-only types.
     AT_TEST([%skeleton "]b4_skel["
              %code requires { #include <memory> }