make V compilable on Windows with mingw-w64

compiler/main.v

@@ -523,7 +523,7 @@ mut args := ''
 		}
 		println('linux cross compilation done. resulting binary: "$c.out_name"')
 	}
-	// print_time('after gcc')
+	//os.rm('$TmpPath/$c.out_name_c') 
 }
 
 fn (c &V) v_files_from_dir(dir string) []string {
@@ -851,6 +851,10 @@ fn new_v(args[]string) *V {
 }
 
 fn run_repl() []string {
+	if $windows {
+		println('REPL does not work on Windows yet, sorry!') 
+		exit1() 
+	} 
 	println('V $Version')
 	println('Use Ctrl-D to exit')
 	println('For now you have to use println() to print values, this will be fixed soon\n')
@@ -900,6 +904,7 @@ Options:
   -obf              Obfuscate the resulting binary.
   run               Build and execute a V program.
                     You can add arguments after file name.
+
 Files:
   <file>_test.v     Test file.
 '

os/os.v

@@ -271,12 +271,22 @@ pub fn getenv(key string) string {
 }
 
 pub fn setenv(name string, value string, overwrite bool) int {
+$if windows {
+ 
+} 
+$else { 
   return C.setenv(name.cstr(), value.cstr(), overwrite)
 } 
+}
 
 pub fn unsetenv(name string) int {
+$if windows {
+ 
+} 
+$else { 
   return C.unsetenv(name.cstr())
 } 
+}
 
 // `file_exists` returns true if `path` exists.
 pub fn file_exists(path string) bool {
@@ -370,21 +380,30 @@ pub fn filename(path string) string {
 //Otherwise, it would cause a valgrind warning and may be dangerous
 //Malloc takes an int as argument so a cast has to be made
 pub fn get_line() string {
+	$if windows {
+		panic('get_line() not implemented on Windows yet, sorry!') 
+	} 
+	$else { 
 		max := u64(256)
 		buf := malloc(int(max))
 		nr_chars := C.getline(&buf, &max, stdin)
 		if nr_chars == 0 {
 			return ''
 		}
-	if buf[nr_chars - 1] == `\n` /* newline */ {
+		if buf[nr_chars - 1] == `\n` { // newline  
 			return tos(buf, nr_chars - 1)
 		}
-	/* To prevent cutting end of line if no newline */
+		// To prevent cutting end of line if no newline  
 		return tos(buf, nr_chars)
+	} 
 }
 
 // get_raw_line returns a one-line string from stdin along with '\n' if there is any
 pub fn get_raw_line() string {
+	$if windows {
+		panic('get_raw_line() not implemented on Windows yet, sorry!') 
+	} 
+	$else { 
 		max := u64(256)
 		buf := malloc(int(max))
 		nr_chars := C.getline(&buf, &max, stdin)
@@ -392,6 +411,7 @@ pub fn get_raw_line() string {
 			return ''
 		}
 		return tos(buf, nr_chars)
+	} 
 }
 
 pub fn user_os() string {