c++: make stack.hh completely useless

Let's completely deprecate stack.hh.  Don't provide a means to give it
a new name, allow only its removal.

See https://lists.gnu.org/archive/html/bison-patches/2018-09/msg00151.html
and https://lists.gnu.org/archive/html/bison-patches/2018-09/msg00182.html.

* data/stack.hh: Reduce stack.hh to a simple comment explaining how to
get rid of it.
* data/lalr1.cc: Adjust
* tests/input.at (%define file variables): Adjust.
* tests/output.at: Remove cases where stack.hh was removed.

data/lalr1.cc

@@ -163,8 +163,6 @@ m4_define([b4_shared_declarations],
 # include <vector>
 
 ]b4_cxx_portability[
-]m4_ifdef([b4_stack_file],
-          [[# include "]b4_stack_file["]])[
 ]m4_ifdef([b4_position_file],
           [[# include "]b4_position_file["]])[
 ]m4_ifdef([b4_location_file],
@@ -178,7 +176,7 @@ m4_define([b4_shared_declarations],
 
 ]b4_namespace_open[
 
-]m4_ifndef([b4_stack_file], [b4_stack_define])[
+]b4_stack_define[
 ]b4_bison_locations_if([m4_ifndef([b4_location_file],
                                   [m4_ifndef([b4_position_file], [b4_position_define
 

data/stack.hh

@@ -15,15 +15,14 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-m4_pushdef([b4_copyright_years],
-           [2002-2015, 2018])
 
 # b4_stack_file
 # -------------
 # Name of the file containing the stack class, if we want this file.
-b4_percent_define_check_file([b4_stack_file],
+b4_percent_define_ifdef([[api.stack.file]],
-                             [[api.stack.file]],
+[b4_percent_define_check_values([[[[api.stack.file]],
-                             b4_defines_if([[stack.hh]]))
+                                  [[none]]]])],
+[b4_defines_if([m4_define([b4_stack_file], [stack.hh])])])
 
 
 # b4_stack_define
@@ -140,25 +139,13 @@ m4_define([b4_stack_define],
 
 m4_ifdef([b4_stack_file],
 [b4_output_begin([b4_dir_prefix[]b4_stack_file])[
-]b4_copyright([Stack handling for Bison parsers in C++])[
+// Starting with Bison 3.2, this file is useless: the structure it
+// used to define is now defined with the parser itself.
+//
+// To get rid of this file:
+// 1. add '%define api.stack.file none' to your grammar file
+// 2. add 'require "3.2"' to your grammar file
+// 3. remove references to this file from your build system.
 
-/**
- ** \file ]b4_dir_prefix[]b4_stack_file[
- ** Define the ]b4_namespace_ref[::stack class.
- */
-
-]b4_cpp_guard_open([b4_dir_prefix[]b4_stack_file])[
-
-# include <vector>
-
-]b4_cxx_portability[
-
-]b4_namespace_open[
-]b4_stack_define[
-]b4_namespace_close[
-
-]b4_cpp_guard_close([b4_dir_prefix[]b4_stack_file])[
 ]b4_output_end[
 ]])
-
-m4_popdef([b4_copyright_years])

tests/calc.at

@@ -694,10 +694,8 @@ AT_CHECK_CALC_LALR1_CC([%defines %locations %define parse.error verbose %debug %
 AT_CHECK_CALC_LALR1_CC([%define parse.error verbose %debug %define api.prefix {calc} %verbose %yacc %parse-param {semantic_value *result} %parse-param {int *count}])
 AT_CHECK_CALC_LALR1_CC([%defines %locations %define parse.error verbose %debug %define api.prefix {calc} %verbose %yacc %parse-param {semantic_value *result} %parse-param {int *count}])
 
-AT_CHECK_CALC_LALR1_CC([%locations %define api.stack.file "my-stack.hh"])
 AT_CHECK_CALC_LALR1_CC([%locations %defines %define api.stack.file none %define api.location.file none %define api.position.file none])
-AT_CHECK_CALC_LALR1_CC([%defines %locations %define api.stack.file "my-stack.hh"])
+AT_CHECK_CALC_LALR1_CC([%defines %locations %define api.stack.file none %define api.position.file none %define api.location.file "my-location.hh"])
-AT_CHECK_CALC_LALR1_CC([%defines %locations %define api.stack.file "my-stack.hh" %define api.position.file none %define api.location.file "my-location.hh"])
 
 
 # --------------------------- #

tests/input.at

@@ -1673,9 +1673,10 @@ AT_BISON_CHECK([[-fcaret input.y]], [[1]], [[]],
 input.y:4.9-25: error: %define variable 'api.location.file' requires 'none' or '"..."' values
  %define api.location.file {bogus}
          ^^^^^^^^^^^^^^^^^
-input.y:3.9-22: error: %define variable 'api.stack.file' requires 'none' or '"..."' values
+input.y:3.9-22: error: invalid value for %define variable 'api.stack.file': 'bogus'
  %define api.stack.file bogus
          ^^^^^^^^^^^^^^
+input.y:3.9-22:     accepted value: 'none'
 ]])
 
 AT_CLEANUP

tests/output.at

@@ -180,11 +180,6 @@ AT_CHECK_OUTPUT([gram_dir/foo.yy],
                 [output_dir/foo.output output_dir/foo.tab.cc output_dir/foo.tab.hh output_dir/location.hh output_dir/position.hh output_dir/stack.hh])
 
 # api.stack.file.
-AT_CHECK_OUTPUT([foo.yy],
-                [%skeleton "lalr1.cc" %define api.stack.file "foo.sta.hh"],
-                [],
-                [foo.sta.hh foo.tab.cc])
-
 AT_CHECK_OUTPUT([foo.yy],
                 [%skeleton "lalr1.cc" %defines %define api.stack.file none],
                 [],
@@ -216,9 +211,9 @@ AT_CHECK_OUTPUT([foo.yy],
                 [foo.loc.hh foo.pos.hh foo.tab.cc foo.tab.hh])
 
 AT_CHECK_OUTPUT([gram_dir/foo.yy],
-                [%skeleton "lalr1.cc" %verbose %defines %define api.stack.file "foo.sta.hh" %file-prefix "output_dir/foo"],
+                [%skeleton "lalr1.cc" %verbose %defines %file-prefix "output_dir/foo"],
                 [],
-                [output_dir/foo.output output_dir/foo.sta.hh output_dir/foo.tab.cc output_dir/foo.tab.hh])
+                [output_dir/foo.output output_dir/foo.tab.cc output_dir/foo.tab.hh])
 
 
 # AT_CHECK_CONFLICTING_OUTPUT(INPUT-FILE, DIRECTIVES, FLAGS, STDERR,