Raise error if using ev/to-file on MinGW

src/core/ev.c

@@ -3309,10 +3309,7 @@ static JanetFile *get_file_for_stream(JanetStream *stream) {
     FILE *f = _fdopen(fd_dup, fmt);
     if (NULL == f) {
         /* the stream isn't duplicated so this would close the stream
-        /* _close(fd); */
-        return NULL;
-    }
-    if (setvbuf(f, NULL, _IONBF, 0)) {
+         * _close(fd); */
         return NULL;
     }
 #else
@@ -3323,24 +3320,26 @@ static JanetFile *get_file_for_stream(JanetStream *stream) {
         close(newHandle);
         return NULL;
     }
-    if (setvbuf(f, NULL, _IONBF, 0)) {
-        close(newHandle);
-        return NULL;
-    }
 #endif
     return janet_makejfile(f, flags);
 }
 
 JANET_CORE_FN(janet_cfun_to_file,
               "(ev/to-file)",
               "Create core/file copy of the stream. This value can be used "
-              "when blocking IO behavior is needed. Buffering is turned off "
-              "for the file.") {
+              "when blocking IO behavior is needed.") {
     janet_fixarity(argc, 1);
+#ifdef JANET_MINGW
+    (void) argc;
+    (void) argv;
+    janet_panic("ev/to-file not supported on MinGW");
+    return janet_wrap_nil();
+#else
     JanetStream *stream = janet_getabstract(argv, 0, &janet_stream_type);
     JanetFile *iof = get_file_for_stream(stream);
     if (iof == NULL) janet_panic("cannot make file from stream");
     return janet_wrap_abstract(iof);
+#endif
 }
 
 JANET_CORE_FN(janet_cfun_ev_all_tasks,

test/suite-ev.janet

@@ -420,9 +420,13 @@
 # Now do our telnet chat
 (def bob (net/connect test-host test-port :stream))
 (expect-read bob "Whats your name?\n")
-(def fbob (ev/to-file bob))
-(file/write fbob "bob")
-(:close fbob)
+(if (= :mingw (os/which))
+  (net/write bob "bob")
+  (do
+    (def fbob (ev/to-file bob))
+    (file/write fbob "bob")
+    (file/flush fbob)
+    (:close fbob)))
 (expect-read bob "Welcome bob\n")
 (def alice (net/connect test-host test-port))
 (expect-read alice "Whats your name?\n")