Fix signed vs unsigned comparisons in string_util unit tests (#742)

Unit-tests fail to build due to the following errors:

/home/cfx/Dev/google-benchmark/benchmark.git/test/string_util_gtest.cc:12:5: required from here
/home/cfx/Applications/googletest-1.8.1/include/gtest/gtest.h:1444:11: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
   if (lhs == rhs) {
       ~~~~^~~~~~

Fixes #741

CONTRIBUTORS

@@ -27,6 +27,7 @@ Arne Beer <arne@twobeer.de>
 Billy Robert O'Neal III <billy.oneal@gmail.com> <bion@microsoft.com>
 Chris Kennelly <ckennelly@google.com> <ckennelly@ckennelly.com>
 Christopher Seymour <chris.j.seymour@hotmail.com>
+Cyrille Faucheux <cyrille.faucheux@gmail.com>
 David Coeurjolly <david.coeurjolly@liris.cnrs.fr>
 Deniz Evrenci <denizevrenci@gmail.com>
 Dominic Hamon <dma@stripysock.com> <dominic@google.com>

test/string_util_gtest.cc

@@ -9,56 +9,56 @@ namespace {
 TEST(StringUtilTest, stoul) {
   {
     size_t pos = 0;
-    EXPECT_EQ(0, benchmark::stoul("0", &pos));
+    EXPECT_EQ(0ul, benchmark::stoul("0", &pos));
-    EXPECT_EQ(1, pos);
+    EXPECT_EQ(1ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(7, benchmark::stoul("7", &pos));
+    EXPECT_EQ(7ul, benchmark::stoul("7", &pos));
-    EXPECT_EQ(1, pos);
+    EXPECT_EQ(1ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(135, benchmark::stoul("135", &pos));
+    EXPECT_EQ(135ul, benchmark::stoul("135", &pos));
-    EXPECT_EQ(3, pos);
+    EXPECT_EQ(3ul, pos);
   }
 #if ULONG_MAX == 0xFFFFFFFFul
   {
     size_t pos = 0;
     EXPECT_EQ(0xFFFFFFFFul, benchmark::stoul("4294967295", &pos));
-    EXPECT_EQ(10, pos);
+    EXPECT_EQ(10ul, pos);
   }
 #elif ULONG_MAX == 0xFFFFFFFFFFFFFFFFul
   {
     size_t pos = 0;
     EXPECT_EQ(0xFFFFFFFFFFFFFFFFul, benchmark::stoul("18446744073709551615", &pos));
-    EXPECT_EQ(20, pos);
+    EXPECT_EQ(20ul, pos);
   }
 #endif
   {
     size_t pos = 0;
-    EXPECT_EQ(10, benchmark::stoul("1010", &pos, 2));
+    EXPECT_EQ(10ul, benchmark::stoul("1010", &pos, 2));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(520, benchmark::stoul("1010", &pos, 8));
+    EXPECT_EQ(520ul, benchmark::stoul("1010", &pos, 8));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(1010, benchmark::stoul("1010", &pos, 10));
+    EXPECT_EQ(1010ul, benchmark::stoul("1010", &pos, 10));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(4112, benchmark::stoul("1010", &pos, 16));
+    EXPECT_EQ(4112ul, benchmark::stoul("1010", &pos, 16));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
-    EXPECT_EQ(0xBEEF, benchmark::stoul("BEEF", &pos, 16));
+    EXPECT_EQ(0xBEEFul, benchmark::stoul("BEEF", &pos, 16));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     ASSERT_THROW(benchmark::stoul("this is a test"), std::invalid_argument);
@@ -69,42 +69,42 @@ TEST(StringUtilTest, stoi) {
   {
     size_t pos = 0;
     EXPECT_EQ(0, benchmark::stoi("0", &pos));
-    EXPECT_EQ(1, pos);
+    EXPECT_EQ(1ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(-17, benchmark::stoi("-17", &pos));
-    EXPECT_EQ(3, pos);
+    EXPECT_EQ(3ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(1357, benchmark::stoi("1357", &pos));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(10, benchmark::stoi("1010", &pos, 2));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(520, benchmark::stoi("1010", &pos, 8));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(1010, benchmark::stoi("1010", &pos, 10));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(4112, benchmark::stoi("1010", &pos, 16));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(0xBEEF, benchmark::stoi("BEEF", &pos, 16));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     ASSERT_THROW(benchmark::stoi("this is a test"), std::invalid_argument);
@@ -115,28 +115,28 @@ TEST(StringUtilTest, stod) {
   {
     size_t pos = 0;
     EXPECT_EQ(0.0, benchmark::stod("0", &pos));
-    EXPECT_EQ(1, pos);
+    EXPECT_EQ(1ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(-84.0, benchmark::stod("-84", &pos));
-    EXPECT_EQ(3, pos);
+    EXPECT_EQ(3ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(1234.0, benchmark::stod("1234", &pos));
-    EXPECT_EQ(4, pos);
+    EXPECT_EQ(4ul, pos);
   }
   {
     size_t pos = 0;
     EXPECT_EQ(1.5, benchmark::stod("1.5", &pos));
-    EXPECT_EQ(3, pos);
+    EXPECT_EQ(3ul, pos);
   }
   {
     size_t pos = 0;
     /* Note: exactly representable as double */
     EXPECT_EQ(-1.25e+9, benchmark::stod("-1.25e+9", &pos));
-    EXPECT_EQ(8, pos);
+    EXPECT_EQ(8ul, pos);
   }
   {
     ASSERT_THROW(benchmark::stod("this is a test"), std::invalid_argument);