Fix windows build

src/main.rs

@@ -38,6 +38,7 @@ mod license;
 use ascii_art::AsciiArt;
 use commit_info::CommitInfo;
 use error::Error;
+#[cfg(target_os = "linux")]
 use image_backends::ImageBackend;
 use info::Info;
 use language::Language;
@@ -100,6 +101,11 @@ fn main() -> Result<()> {
         .map(|language| language.to_string().to_lowercase())
         .collect();
 
+    #[cfg(target_os = "linux")]
+    let possible_backends = ["kitty", "sixel"];
+    #[cfg(not(target_os = "linux"))]
+    let possible_backends = [];
+
     let matches = App::new(crate_name!())
         .version(crate_version!())
         .author("o2sh <[email protected]>")
@@ -197,7 +203,7 @@ Possible values: [{0}{1}{2}{3}{4}{5}{6}{7}{8}{9}{10}{11}{12}{13}{14}{15}]",
             Arg::with_name("image-backend")
                 .long("image-backend")
                 .takes_value(true)
-                .possible_values(&["kitty", "sixel"])
+                .possible_values(&possible_backends)
                 .help("Overrides image backend detection"),
         )
         .arg(
@@ -269,11 +275,14 @@ Possible values: [{0}{1}{2}{3}{4}{5}{6}{7}{8}{9}{10}{11}{12}{13}{14}{15}]",
     let image_backend = if custom_image.is_some() {
         if let Some(backend_name) = matches.value_of("image-backend") {
             #[cfg(target_os = "linux")]
-            Some(match backend_name {
+            let backend = Some(match backend_name {
                 "kitty" => Box::new(image_backends::kitty::KittyBackend::new()) as Box<dyn ImageBackend>,
                 "sixel" => Box::new(image_backends::sixel::SixelBackend::new()) as Box<dyn ImageBackend>,
                 _ => unreachable!()
-            })
+            });
+            #[cfg(not(target_os = "linux"))]
+            let backend = None;
+            backend
         } else {
             crate::image_backends::get_best_backend()
         }