[Fuzzer] Update of SetThreadName for Windows

[devnexen]

Summary

After trying out, it is safe to assume it goes further than a buffer of 16, also now needs to account the terminator.

[vitalybuka]

Please abandon this one, let's try https://reviews.llvm.org/D156317 again

[devnexen]

• advices from vitalybuka.

[devnexen]

AH did not notice your comment do you still want me to move back to the other diff ?

[vitalybuka]

In D156418#4540287, @devnexen wrote:

AH did not notice your comment do you still want me to move back to the other diff ?

That's how we usually do: revert and reopen

compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp

242

Looks like you also didn't compile on windows?

name.data, name.size -> name.data(), name.size()

Make sure that uploaded patch is on top of origin/main, pre-merge checks has Windows

242

Looks like you also didn't compile on windows?

That's fine, just make "pre-merge checks" happy

[vitalybuka]

I guess we don't need this one

compiler-rt/lib/fuzzer/FuzzerUtilWindows.cpp

 }
 
 void SetThreadName(std::thread &thread, const std::string &name) {
-  wchar_t wname[16];
-  if (MultiByteToWideChar(CP_UTF8, 0, name.c_str(), -1, wname, 16) > 0)
-    (void)SetThreadDescription(thread.native_handle(), wname);
+  auto sz = MultiByteToWideChar(CP_UTF8, 0, name.data(), name.size(), nullptr, 0);
+  if (sz > 0) {
+    std::wstring wname(sz);
+    if (MultiByteToWideChar(CP_UTF8, 0, name.data, name.size, &wname[0], sz) > 0) {
+      wname.resize(sz - 1);
+      (void)SetThreadDescription(thread.native_handle(), wname.c_str());
+    }
+  }
 }
 
 } // namespace fuzzer