[PATCH v4 1/2] msvcrt: Don't set error in wcstombs_s_l if no characters to convert.

[Piotr Caban]

On 2/5/20 3:39 PM, Daniel Lehman wrote:
      if(!mbstr) {
          tmp = WideCharToMultiByte(locinfo->lc_codepage, 
WC_NO_BEST_FIT_CHARS,
-                *wcstr, -1, NULL, 0, NULL, &used_default)-1;
-        if(!tmp || used_default) {
+                *wcstr, -1, NULL, 0, NULL, &used_default);
+        if(used_default) {
              *MSVCRT__errno() = MSVCRT_EILSEQ;
              return -1;
          }

I think we should still set errno when WideCharToMultiByte fails (the 
!tmp case).

Thanks,
Piotr