Remove automatic Bison invocation for blink's xpath_grammar.y

To avoid targeting many versions of Bison, we will now require editors
of xpath_grammar.y to manually regenerate the generated files. See
xpath_grammar.y for instructions on running Bison.

Since we're only targeting new versions of Bison, we can now replace
the %pure-parser directive with the equivalent %define. As a result,
we no longer need to silence the warning about %pure-parser.

Also removing //third_party/bison from DEPS, which contains a snapshot
of a Windows fork of Bison 2.4.1 (from 2012).

Bug: 1028421
Change-Id: I8deb986f0cafb8e7f093c5def71d427709a4a845
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954609Reviewed-by: Chris Palmer <palmer@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722623}

DEPS

@@ -797,11 +797,6 @@ deps = {
       'dep_type': 'cipd',
   },
 
-  'src/third_party/bison': {
-      'url': Var('chromium_git') + '/chromium/deps/bison.git' + '@' + '083c9a45e4affdd5464ee2b224c2df649c6e26c3',
-      'condition': 'checkout_win',
-  },
-
   'src/third_party/boringssl/src':
     Var('boringssl_git') + '/boringssl.git' + '@' +  Var('boringssl_revision'),
 

third_party/blink/PRESUBMIT.py

@@ -4,13 +4,14 @@
 
 """Top-level presubmit script for Blink.
 
-See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+See https://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
 import imp
 import inspect
 import os
+import re
 
 try:
     # pylint: disable=C0103
@@ -103,6 +104,10 @@ def _FilterPaths(input_api):
             continue
         if '/PRESUBMIT' in file_path:
             continue
+        # Skip files that were generated by bison.
+        if re.search('third_party/blink/renderer/' +
+                     'core/xml/xpath_grammar_generated\.(cc|h)$', file_path):
+          continue
         files.append(input_api.os_path.join('..', '..', file_path))
     return files
 

third_party/blink/renderer/build/scripts/rule_bison.py

@@ -62,13 +62,14 @@ assert inputName == 'xpath_grammar.y'
 prefix = {'xpath_grammar.y': 'xpathyy'}[inputName]
 
 (inputRoot, inputExt) = os.path.splitext(inputName)
+newInputRoot = inputRoot + '_generated'
 
 # The generated .h will be in a different location depending on the bison
 # version.
 outputHTries = [
-    os.path.join(outputDir, inputRoot + '.cpp.h'),
-    os.path.join(outputDir, inputRoot + '.hpp'),
-    os.path.join(outputDir, inputRoot + '.hh'),
+    os.path.join(outputDir, newInputRoot + '.cpp.h'),
+    os.path.join(outputDir, newInputRoot + '.hpp'),
+    os.path.join(outputDir, newInputRoot + '.hh'),
 ]
 
 for outputHTry in outputHTries:
@@ -78,7 +79,7 @@ for outputHTry in outputHTries:
         if e.errno != errno.ENOENT:
             raise
 
-outputCpp = os.path.join(outputDir, inputRoot + '.cc')
+outputCpp = os.path.join(outputDir, newInputRoot + '.cc')
 
 returnCode = subprocess.call([bisonExe, '-d', '-p', prefix, inputFile, '-o', outputCpp])
 assert returnCode == 0
@@ -96,21 +97,26 @@ for outputHTry in outputHTries:
 
 assert outputHTmp != None
 
-# Read the header file in under the generated name and remove it.
-outputHFile = open(outputHTmp)
-outputHContents = outputHFile.read()
-outputHFile.close()
-os.unlink(outputHTmp)
 
-# Rewrite the generated header with #include guards.
-outputH = os.path.join(outputDir, inputRoot + '.h')
-
-outputHInGen = outputH.replace('gen/', '')
-headerGuard = NameStyleConverter(outputHInGen).to_header_guard()
+def modifyFile(path, prefixLines, suffixLines):
+    prefixLines = map(lambda s: s + '\n', prefixLines)
+    suffixLines = map(lambda s: s + '\n', suffixLines)
+    with open(path, 'r') as f:
+        oldLines = f.readlines()
+    newLines = prefixLines + oldLines + suffixLines
+    with open(path, 'w') as f:
+        f.writelines(newLines)
 
-outputHFile = open(outputH, 'w')
-print >>outputHFile, '#ifndef %s' % headerGuard
-print >>outputHFile, '#define %s' % headerGuard
-print >>outputHFile, outputHContents
-print >>outputHFile, '#endif  // %s' % headerGuard
-outputHFile.close()
+# Rewrite the generated header with #include guards.
+kClangFormatDisableLine = "// clang-format off"
+outputH = os.path.join(outputDir, newInputRoot + '.h')
+headerGuard = NameStyleConverter(outputH).to_header_guard()
+modifyFile(outputHTmp,
+           [kClangFormatDisableLine,
+            '#ifndef %s' % headerGuard,
+            '#define %s' % headerGuard,
+            ], ['#endif  // %s' % headerGuard]
+           )
+os.rename(outputHTmp, outputH)
+
+modifyFile(outputCpp, [kClangFormatDisableLine], [])

third_party/blink/renderer/build/scripts/scripts.gni

@@ -71,13 +71,10 @@ make_trie_helpers_files =
 # on Posix we want to run the system one on the path.
 if (host_os == "win") {
   gperf_exe = rebase_path("//third_party/gperf/bin/gperf.exe", root_build_dir)
-  bison_exe = rebase_path("//third_party/bison/bin/bison.exe", root_build_dir)
 } else if (is_mac) {
   gperf_exe = mac_bin_path + "gperf"
-  bison_exe = mac_bin_path + "bison"
 } else {
   gperf_exe = "gperf"
-  bison_exe = "bison"
 }
 
 # Templates --------------------------------------------------------------------

third_party/blink/renderer/core/BUILD.gn

@@ -944,30 +944,11 @@ blink_python_runner("make_core_generated_web_origin_trials") {
   ]
 }
 
-action_foreach("make_core_generated_bison") {
-  script = "../build/scripts/rule_bison.py"
-  sources = [
-    "xml/xpath_grammar.y",
-  ]
-  outputs = [
-    "$blink_core_output_dir/{{source_name_part}}.cc",
-    "$blink_core_output_dir/{{source_name_part}}.h",
-  ]
-  args = [
-    "{{source}}",
-    rel_blink_core_gen_dir,
-    bison_exe,
-  ]
-
-  deps = make_core_generated_deps
-}
-
 # Targets from above that generate outputs that need to be compiled.
 # All sources declared as outputs from these targets will be compiled into one
 # target.
 targets_generating_sources = [
   ":make_core_generated_atrule_names",
-  ":make_core_generated_bison",
   ":make_core_generated_css_primitive_value_unit_trie",
   ":make_core_generated_computed_style_initial_values",
   ":make_core_generated_computed_style_base",

third_party/blink/renderer/core/xml/BUILD.gn

@@ -35,6 +35,8 @@ blink_core_sources("xml") {
     "xpath_expression_node.h",
     "xpath_functions.cc",
     "xpath_functions.h",
+    "xpath_grammar_generated.cc",
+    "xpath_grammar_generated.h",
     "xpath_node_set.cc",
     "xpath_node_set.h",
     "xpath_ns_resolver.h",
@@ -64,11 +66,4 @@ blink_core_sources("xml") {
     "xslt_unicode_sort.cc",
     "xslt_unicode_sort.h",
   ]
-
-  # XCode's ancient bison (v2.3 from 2006) prevents us from updating a
-  # deprecated bison directive. This will silence the warning.
-  # See https://crbug.com/1028421.
-  if (!is_mac) {
-    cflags = [ "-Wno-deprecated" ]
-  }
 }

third_party/blink/renderer/core/xml/xpath_grammar.y

@@ -25,6 +25,21 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+/* === NOTA BENE ===
+ * If you modify this file, you must run bison to regenerate the corresponding
+ * .cc and .h files. From chromium's root directory, run the following command
+ * on a system with a modern version of bison (>= 3.4.1):
+ *
+ *   $ third_party/blink/renderer/build/scripts/rule_bison.py \
+ *       third_party/blink/renderer/core/xml/xpath_grammar.y \
+ *       third_party/blink/renderer/core/xml/ \
+ *       bison
+ *
+ * This process is not automated because newer bison releases have diverged from
+ * (1) the version included with Xcode and (2) the Windows binary checked into
+ * //third_party/bison. See https://crbug.com/1028421.
+ */
+
 %{
 
 #include "third_party/blink/renderer/core/xml/xpath_functions.h"
@@ -51,7 +66,7 @@
 using blink::xpath::Step;
 %}
 
-%pure-parser
+%define api.pure full
 %parse-param { blink::xpath::Parser* parser }
 
 %union

third_party/blink/renderer/core/xml/xpath_grammar_generated.h

+// clang-format off
+#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_H_
+#define THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_H_
+/* A Bison parser, made by GNU Bison 3.4.1.  */
+
+/* Bison interface for Yacc-like parsers in C
+
+   Copyright (C) 1984, 1989-1990, 2000-2015, 2018-2019 Free Software Foundation,
+   Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* As a special exception, you may create a larger work that contains
+   part or all of the Bison parser skeleton and distribute that work
+   under terms of your choice, so long as that work isn't itself a
+   parser generator using the skeleton or a modified version thereof
+   as a parser skeleton.  Alternatively, if you modify or redistribute
+   the parser skeleton itself, you may (at your option) remove this
+   special exception, which will cause the skeleton and the resulting
+   Bison output files to be licensed under the GNU General Public
+   License without this special exception.
+
+   This special exception was added by the Free Software Foundation in
+   version 2.2 of Bison.  */
+
+/* Undocumented macros, especially those whose name start with YY_,
+   are private implementation details.  Do not rely on them.  */
+
+#ifndef YY_XPATHYY_THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_HH_INCLUDED
+# define YY_XPATHYY_THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_HH_INCLUDED
+/* Debug traces.  */
+#ifndef YYDEBUG
+# define YYDEBUG 0
+#endif
+#if YYDEBUG
+extern int xpathyydebug;
+#endif
+
+/* Token type.  */
+#ifndef YYTOKENTYPE
+# define YYTOKENTYPE
+  enum yytokentype
+  {
+    MULOP = 258,
+    EQOP = 259,
+    RELOP = 260,
+    PLUS = 261,
+    MINUS = 262,
+    OR = 263,
+    AND = 264,
+    AXISNAME = 265,
+    NODETYPE = 266,
+    PI = 267,
+    FUNCTIONNAME = 268,
+    LITERAL = 269,
+    VARIABLEREFERENCE = 270,
+    NUMBER = 271,
+    DOTDOT = 272,
+    SLASHSLASH = 273,
+    NAMETEST = 274,
+    XPATH_ERROR = 275
+  };
+#endif
+
+/* Value type.  */
+#if ! defined YYSTYPE && ! defined YYSTYPE_IS_DECLARED
+union YYSTYPE
+{
+#line 73 "third_party/blink/renderer/core/xml/xpath_grammar.y"
+
+  blink::xpath::Step::Axis axis;
+  blink::xpath::Step::NodeTest* node_test;
+  blink::xpath::NumericOp::Opcode num_op;
+  blink::xpath::EqTestOp::Opcode eq_op;
+  String* str;
+  blink::xpath::Expression* expr;
+  blink::HeapVector<blink::Member<blink::xpath::Predicate>>* pred_list;
+  blink::HeapVector<blink::Member<blink::xpath::Expression>>* arg_list;
+  blink::xpath::Step* step;
+  blink::xpath::LocationPath* location_path;
+
+#line 91 "third_party/blink/renderer/core/xml/xpath_grammar_generated.hh"
+
+};
+typedef union YYSTYPE YYSTYPE;
+# define YYSTYPE_IS_TRIVIAL 1
+# define YYSTYPE_IS_DECLARED 1
+#endif
+
+
+
+int xpathyyparse (blink::xpath::Parser* parser);
+
+#endif /* !YY_XPATHYY_THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_HH_INCLUDED  */
+#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_GRAMMAR_GENERATED_H_

third_party/blink/renderer/core/xml/xpath_parser.cc

@@ -29,9 +29,9 @@
 
 #include "base/memory/ptr_util.h"
 #include "third_party/blink/renderer/core/xml/xpath_evaluator.h"
+#include "third_party/blink/renderer/core/xml/xpath_grammar_generated.h"
 #include "third_party/blink/renderer/core/xml/xpath_ns_resolver.h"
 #include "third_party/blink/renderer/core/xml/xpath_path.h"
-#include "third_party/blink/renderer/core/xpath_grammar.h"
 #include "third_party/blink/renderer/platform/bindings/exception_state.h"
 #include "third_party/blink/renderer/platform/wtf/std_lib_extras.h"
 #include "third_party/blink/renderer/platform/wtf/text/string_hash.h"