os: return the long path for os.temp_dir() on windows, even for folders like c:\someth~1 (#17623)

vlib/os/os.v

@@ -716,6 +716,7 @@ pub fn temp_dir() string {
 				path = 'C:/tmp'
 			}
 		}
+		path = get_long_path(path) or { path }
 	}
 	$if macos {
 		// avoid /var/folders/6j/cmsk8gd90pd.... on macs

vlib/os/os_js.js.v

@@ -183,3 +183,9 @@ pub fn is_readable(path string) bool {
 		return false
 	}
 }
+
+// get_long_path has no meaning for *nix, but has for windows, where `c:\folder\some~1` for example
+// can be the equivalent of `c:\folder\some spa ces`. On *nix, it just returns a copy of the input path.
+fn get_long_path(path string) !string {
+	return path
+}

vlib/os/os_nix.c.v

@@ -500,3 +500,9 @@ pub fn posix_set_permission_bit(path_s string, mode u32, enable bool) {
 	}
 	C.chmod(path, int(new_mode))
 }
+
+// get_long_path has no meaning for *nix, but has for windows, where `c:\folder\some~1` for example
+// can be the equivalent of `c:\folder\some spa ces`. On *nix, it just returns a copy of the input path.
+fn get_long_path(path string) !string {
+	return path
+}

vlib/os/os_windows.c.v

@@ -558,3 +558,24 @@ pub fn (mut c Command) read_line() string {
 pub fn (mut c Command) close() ! {
 	panic('not implemented')
 }
+
+fn C.GetLongPathName(short_path &u16, long_path &u16, long_path_bufsize u32) u32
+
+// get_long_path has no meaning for *nix, but has for windows, where `c:\folder\some~1` for example
+// can be the equivalent of `c:\folder\some spa ces`. On *nix, it just returns a copy of the input path.
+fn get_long_path(path string) !string {
+	if !path.contains('~') {
+		return path
+	}
+	input_short_path := path.to_wide()
+	defer {
+		unsafe { free(input_short_path) }
+	}
+	long_path_buf := [4096]u16{}
+	res := C.GetLongPathName(input_short_path, &long_path_buf[0], sizeof(long_path_buf))
+	if res == 0 {
+		return error(get_error_msg(int(C.GetLastError())))
+	}
+	long_path := unsafe { string_from_wide(&long_path_buf[0]) }
+	return long_path
+}

vlib/os/signal.js.v

@@ -115,7 +115,7 @@ fn signal_from_str(str JS.String) Signal {
 // - Browser: Will use `window.addEventListener` for handling signal
 //
 // TODO: Add signal events implementation for browser backend
-pub fn signal_opt(signum Signal, handler SignalHandler) ?SignalHandler {
+pub fn signal_opt(signum Signal, handler SignalHandler) !SignalHandler {
 	signame := signal_str(signum)
 	_ := signame
 	$if js_node {