Link app icon using build script

.cargo/config.toml

@@ -9,9 +9,5 @@
 # ```
 # and checking that the output doesn't contain any MSVCR DLLs
 
-[target.'cfg(all(target_arch = "x86_64", target_os = "windows", target_env = "msvc")']
-rustflags = [
-    "-Ctarget-feature=+crt-static",
-    "-L./icon",
-    "-Clink-args=resources.res",
-]
+[target.x86_64-pc-windows-msvc]
+rustflags = ["-Ctarget-feature=+crt-static"]

cli/build.rs

@@ -0,0 +1,21 @@
+use std::{env, error, fs};
+
+fn link_icon() -> Result<(), Box<dyn error::Error>> {
+	if env::var("TARGET")? == "x86_64-pc-windows-msvc" {
+		println!("cargo::rerun-if-changed=../icon/resources.res");
+		if fs::exists("../icon/resources.res")? {
+			println!("cargo::rustc-link-arg-bins=icon/resources.res");
+		} else {
+			return Err(
+				"could not find `resources.res` file; fend will not have an app icon".into(),
+			);
+		}
+	}
+	Ok(())
+}
+
+fn main() {
+	if let Err(e) = link_icon() {
+		println!("cargo::warning={e}");
+	}
+}