From 5ef8c456834cf39134980fee42601825d6f30387 Mon Sep 17 00:00:00 2001
From: Ryan Harrison <rharrison@chromium.org>
Date: Tue, 31 Aug 2021 18:00:17 +0000
Subject: [PATCH] Check for leading zeros on decimal integer literals

Fixes:tint:1124
Change-Id: I6cab684423081889d27b266628089c55918e1f9f
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/62320
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
---
 src/reader/wgsl/lexer.cc      | 21 ++++++++++++++-------
 src/reader/wgsl/lexer_test.cc |  7 ++++++-
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/reader/wgsl/lexer.cc b/src/reader/wgsl/lexer.cc
index e4be0bc09c..74afcf6b66 100644
--- a/src/reader/wgsl/lexer.cc
+++ b/src/reader/wgsl/lexer.cc
@@ -593,9 +593,19 @@ Token Lexer::try_integer() {
   }
 
   auto first = end;
-  while (end < len_ && is_digit(content_->data[end])) {
-    end++;
+  // If the first digit is a zero this must only be zero as leading zeros
+  // are not allowed.
+  auto next = first + 1;
+  if (next < len_) {
+    if (content_->data[first] == '0' && is_digit(content_->data[next])) {
+      return {Token::Type::kError, source,
+              "integer literal (" +
+                  content_->data.substr(start, end - 1 - start) +
+                  "...) has leading 0s"};
+    }
+  }
 
+  while (end < len_ && is_digit(content_->data[end])) {
     auto digits = end - first;
     if (digits > kMaxDigits) {
       return {Token::Type::kError, source,
@@ -603,12 +613,9 @@ Token Lexer::try_integer() {
                   content_->data.substr(start, end - 1 - start) +
                   "...) has too many digits"};
     }
-  }
 
-  // If the first digit is a zero this must only be zero as leading zeros
-  // are not allowed.
-  if (content_->data[first] == '0' && (end - first != 1))
-    return {};
+    end++;
+  }
 
   pos_ = end;
   location_.column += (end - start);
diff --git a/src/reader/wgsl/lexer_test.cc b/src/reader/wgsl/lexer_test.cc
index 38482d1dc7..2bc076586a 100644
--- a/src/reader/wgsl/lexer_test.cc
+++ b/src/reader/wgsl/lexer_test.cc
@@ -407,7 +407,12 @@ TEST_P(IntegerTest_Invalid, Parses) {
 }
 INSTANTIATE_TEST_SUITE_P(LexerTest,
                          IntegerTest_Invalid,
-                         testing::Values("2147483648", "4294967296u"));
+                         testing::Values("2147483648",
+                                         "4294967296u",
+                                         "01234",
+                                         "0000",
+                                         "-00",
+                                         "00u"));
 
 struct TokenData {
   const char* input;