Reintroduce duplicate identifier detection in preparser.

test/preparser/duplicate-parameter.pyt

Index: test/preparser/duplicate-parameter.pyt
diff --git a/test/preparser/duplicate-parameter.pyt b/test/preparser/duplicate-parameter.pyt
new file mode 100644
index 0000000000000000000000000000000000000000..4dfb7d691feead4961cee649bd392e114af88c7b
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+++ b/test/preparser/duplicate-parameter.pyt
@@ -0,0 +1,90 @@
+# Copyright 2011 the V8 project authors. All rights reserved.
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+#       copyright notice, this list of conditions and the following
+#       disclaimer in the documentation and/or other materials provided
+#       with the distribution.
+#     * Neither the name of Google Inc. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# Templatated tests with duplicate parameter names.
+
+# ----------------------------------------------------------------------
+# Constants and utility functions
+
+# A template that performs the same strict-mode test in different
+# scopes (global scope, function scope, and nested function scope),
+# and in non-strict mode too.
+def DuplicateParameterTest(name, source):
+  expectation = "strict_param_dupe"
+  non_selfstrict = {"selfstrict":"", "id":"selfnormal"}
+
+  Template(name, '"use strict";\n' + source)(non_selfstrict, expectation)
+  Template(name + '-infunc',
+           'function foo() {\n "use strict";\n' + source +'\n}\n')(
+               non_selfstrict, expectation)
+  Template(name + '-infunc2',
+           'function foo() {\n "use strict";\n  function bar() {\n' +
+           source +'\n }\n}\n')(non_selfstrict, expectation)
+
+  selfstrict = {"selfstrict": "\"use strict\";", "id": "selfstrict"}
+  nestedstrict = {"selfstrict": "function bar(){\"use strict\";}",
+                  "id": "nestedstrict"}
+  selfstrictnestedclean = {"selfstrict": """
+      "use strict";
+      function bar(){}
+    """, "id": "selfstrictnestedclean"}
+  selftest = Template(name + '-$id', source)
+  selftest(selfstrict, expectation)
+  selftest(selfstrictnestedclean, expectation)
+  selftest(nestedstrict, None)
+  selftest(non_selfstrict, None)
+
+
+# ----------------------------------------------------------------------
+# Test templates
+
+DuplicateParameterTest("dups", """
+  function foo(a, a) { $selfstrict }
+""");
+
+DuplicateParameterTest("dups-apart", """
+  function foo(a, b, c, d, e, f, g, h, i, j, k, l, m, n, a) { $selfstrict }
+""");
+
+DuplicateParameterTest("dups-escaped", """
+  function foo(\u0061, b, c, d, e, f, g, h, i, j, k, l, m, n, a) { $selfstrict }
+""");
+
+DuplicateParameterTest("triples", """
+  function foo(a, b, c, d, e, f, g, h, a, i, j, k, l, m, n, a) { $selfstrict }
+""");
+
+DuplicateParameterTest("escapes", """
+  function foo(a, \u0061) { $selfstrict }
+""");
+
+DuplicateParameterTest("long-names", """
+  function foo(arglebargleglopglyfarglebargleglopglyfarglebargleglopglyfa,
+               arglebargleglopglyfarglebargleglopglyfarglebargleglopglyfa) {
+    $selfstrict
+  }
+""");