From b45ed217c61cd69eee2eafd9dbf5798520685538 Mon Sep 17 00:00:00 2001
From: mdempsky <mdempsky@chromium.org>
Date: Tue, 31 Mar 2015 16:58:20 -0700
Subject: [PATCH] tools/gn: disallow non-canonical integer literals

In most languages familiar to Chromium developers (e.g., C++,
JavaScript, Python, Java, Go, Bash, Perl, Ruby), a leading 0 in an
integer literal indicates an octal number.  For example, "010" and
"-010" represent 8 and -8, respectively.

GN doesn't have any use for octal integer literals, so reject integers
with leading zeros to avoid confusion rather than interpreting them as
decimal values.

While here, "-0" isn't useful either since it's equivalent to "0", so
reject that too.

No Chromium BUILD.gn files are affected by this change.

Review URL: https://codereview.chromium.org/1038233002

Cr-Commit-Position: refs/heads/master@{#323142}
---
 tools/gn/parse_tree.cc          | 10 +++++++++-
 tools/gn/parse_tree_unittest.cc | 36 ++++++++++++++++++++++++++++++++++++
 tools/gn/parser.cc              |  2 ++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/tools/gn/parse_tree.cc b/tools/gn/parse_tree.cc
index f5897065548f..5e5b9ea01b71 100644
--- a/tools/gn/parse_tree.cc
+++ b/tools/gn/parse_tree.cc
@@ -634,8 +634,16 @@ Value LiteralNode::Execute(Scope* scope, Err* err) const {
     case Token::FALSE_TOKEN:
       return Value(this, false);
     case Token::INTEGER: {
+      base::StringPiece s = value_.value();
+      if ((s.starts_with("0") && s.size() > 1) || s.starts_with("-0")) {
+        if (s == "-0")
+          *err = MakeErrorDescribing("Negative zero doesn't make sense");
+        else
+          *err = MakeErrorDescribing("Leading zeros not allowed");
+        return Value();
+      }
       int64 result_int;
-      if (!base::StringToInt64(value_.value(), &result_int)) {
+      if (!base::StringToInt64(s, &result_int)) {
         *err = MakeErrorDescribing("This does not look like an integer");
         return Value();
       }
diff --git a/tools/gn/parse_tree_unittest.cc b/tools/gn/parse_tree_unittest.cc
index 827f3d54a5ce..29a0faf36f95 100644
--- a/tools/gn/parse_tree_unittest.cc
+++ b/tools/gn/parse_tree_unittest.cc
@@ -212,3 +212,39 @@ TEST(ParseTree, SortRangeExtraction) {
     EXPECT_EQ(3u, ranges[0].end);
   }
 }
+
+TEST(ParseTree, Integers) {
+  static const char* const kGood[] = {
+      "0",
+      "10",
+      "-54321",
+      "9223372036854775807",   // INT64_MAX
+      "-9223372036854775808",  // INT64_MIN
+  };
+  for (auto s : kGood) {
+    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());
+  }
+
+  static const char* const kBad[] = {
+      "-0",
+      "010",
+      "-010",
+      "9223372036854775808",   // INT64_MAX + 1
+      "-9223372036854775809",  // INT64_MIN - 1
+  };
+  for (auto s : kBad) {
+    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());
+  }
+}
diff --git a/tools/gn/parser.cc b/tools/gn/parser.cc
index 1fa432e3a806..05aab74227bc 100644
--- a/tools/gn/parser.cc
+++ b/tools/gn/parser.cc
@@ -49,6 +49,8 @@ const char kGrammar_Help[] =
     "\n"
     "      integer = [ \"-\" ] digit { digit } .\n"
     "\n"
+    "  Leading zeros and negative zero are disallowed.\n"
+    "\n"
     "String literals\n"
     "\n"
     "  A string literal represents a string value consisting of the quoted\n"
-- 
2.11.4.GIT