From: Johannes Schindelin <redacted>

Johannes Sixt pointed out that the `err_win_to_posix()` function
mishandles `ERROR_SUCCESS`: it maps it to `ENOSYS`.

The only purpose of this function is to map Win32 API errors to `errno`
ones, and there is actually no equivalent to `ERROR_SUCCESS`: the idea
of `errno` is that it will only be set in case of an error, and left
alone in case of success.

Therefore, as pointed out by Junio Hamano, it is a bug to call this
function when there was not even any error to map.

Signed-off-by: Johannes Schindelin <redacted>
---
 compat/mingw.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/compat/mingw.c b/compat/mingw.c
index 432adc1aed..827065d96d 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c

@@ -114,6 +114,7 @@ int err_win_to_posix(DWORD winerr)
 	case ERROR_SHARING_BUFFER_EXCEEDED: error = ENFILE; break;
 	case ERROR_SHARING_VIOLATION: error = EACCES; break;
 	case ERROR_STACK_OVERFLOW: error = ENOMEM; break;
+	case ERROR_SUCCESS: BUG("err_win_to_posix() called without an error!");
 	case ERROR_SWAPERROR: error = ENOENT; break;
 	case ERROR_TOO_MANY_MODULES: error = EMFILE; break;
 	case ERROR_TOO_MANY_OPEN_FILES: error = EMFILE; break;

-- 
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