[SYCL] Fix regression introduced in #11517 (#12002)

This patch fixes a regression caused by refactoring of `split_string`
function in #11517.
The regression is the following: the delimiter is a space, input string
is `"A B C "` - which has a space at the end.
Before #11517 `split_string` returned
`{"A", "B", "C"}` but with #11517 it
returns `{"A", "B", "C", ""}`.
This regression affects multiple CTS tests, verified the fix locally,
and also unit tests for `split_string` function were added to this
patch. This log shows that one of the unit tests failed before applying
the fix:
https://github.com/intel/llvm/actions/runs/6974175043/job/18979466747#step:11:372.
With the fix it passes.

Fixes #11996

Author: dm-vodopyanov

sycl/source/detail/common.cpp

@@ -72,18 +72,24 @@ const char *stringifyErrorCode(pi_int32 error) {
 }
 
 std::vector<std::string> split_string(const std::string &str, char delimeter) {
-  std::vector<std::string> result;
-  size_t beg = 0;
-  size_t end = 0;
-  while ((end = str.find(delimeter, beg)) != std::string::npos) {
-    result.push_back(str.substr(beg, end - beg));
-    beg = end + 1;
+  std::vector<std::string> Result;
+  size_t Start = 0;
+  size_t End = 0;
+  while ((End = str.find(delimeter, Start)) != std::string::npos) {
+    Result.push_back(str.substr(Start, End - Start));
+    Start = End + 1;
   }
-  end = str.find('\0');
-  if (beg < end) {
-    result.push_back(str.substr(beg, end - beg));
+  // Get the last substring and ignore the null character so we wouldn't get
+  // double null characters \0\0 at the end of the substring
+  End = str.find('\0');
+  if (Start < End) {
+    std::string LastSubStr(str.substr(Start, End - Start));
+    // In case str has a delimeter at the end, the substring will be empty, so
+    // we shouldn't add it to the final vector
+    if (!LastSubStr.empty())
+      Result.push_back(LastSubStr);
   }
-  return result;
+  return Result;
 }
 
 } // namespace detail

sycl/unittests/kernel-and-program/DeviceInfo.cpp

@@ -235,3 +235,28 @@ TEST_F(DeviceInfoNegativeTest, TestAspectNotSupported) {
   EXPECT_EQ(Dev.has(aspect::ext_intel_memory_clock_rate), false);
   EXPECT_EQ(Dev.has(aspect::ext_intel_memory_bus_width), false);
 }
+
+TEST_F(DeviceInfoTest, SplitStringDelimeterSpace) {
+  std::string InputString("V1 V2 V3");
+  std::vector<std::string> Expected{"V1", "V2", "V3"};
+  EXPECT_EQ(detail::split_string(InputString, ' '), Expected);
+}
+
+TEST_F(DeviceInfoTest, SplitStringDelimeterSpaceAtTheEnd) {
+  std::string InputString("V1 V2 V3 ");
+  std::vector<std::string> Expected{"V1", "V2", "V3"};
+  EXPECT_EQ(detail::split_string(InputString, ' '), Expected);
+}
+
+TEST_F(DeviceInfoTest, SplitStringDelimeterSemicolon) {
+  std::string InputString("V1;V2;V3");
+  std::vector<std::string> Expected{"V1", "V2", "V3"};
+  EXPECT_EQ(detail::split_string(InputString, ';'), Expected);
+}
+
+TEST_F(DeviceInfoTest, SplitStringCheckNoDoubleNullCharacters) {
+  std::string InputString("V1;V23");
+  std::vector<std::string> Result = detail::split_string(InputString, ';');
+  EXPECT_EQ(Result[0].length(), (unsigned)2);
+  EXPECT_EQ(Result[1].length(), (unsigned)3);
+}