tools/gn: disallow non-canonical integer literals

tools/gn/parse_tree_unittest.cc

Index: tools/gn/parse_tree_unittest.cc
diff --git a/tools/gn/parse_tree_unittest.cc b/tools/gn/parse_tree_unittest.cc
index 827f3d54a5ce55d630a750fdee6163f183646598..51b88f037116f1434ed091568e28e91578aa8a75 100644
--- a/tools/gn/parse_tree_unittest.cc
+++ b/tools/gn/parse_tree_unittest.cc
@@ -212,3 +212,41 @@ TEST(ParseTree, SortRangeExtraction) {
     EXPECT_EQ(3u, ranges[0].end);
   }
 }
+
+TEST(ParseTree, Integers) {
+  const char *good[] = {
+    "0",
+    "10",
+    "-54321",
+    "9223372036854775807",
+    "-9223372036854775808",
+  };
+
+  const char *bad[] = {
+    "-0",
+    "010",
+    "-010",
+    "9223372036854775808",
+    "-9223372036854775809",
+  };
+
+  for (auto s : good) {
+    TestParseInput input(std::string("x = ") + s);
+    EXPECT_FALSE(input.has_error());
+
+    TestWithScope setup;
+    Err err;
+    input.parsed()->Execute(setup.scope(), &err);
+    EXPECT_FALSE(err.has_error());
+  }
+
+  for (auto s : bad) {
+    TestParseInput input(std::string("x = ") + s);
+    EXPECT_FALSE(input.has_error());
+
+    TestWithScope setup;
+    Err err;
+    input.parsed()->Execute(setup.scope(), &err);
+    EXPECT_TRUE(err.has_error());
+  }
+}