Rewrite core-no-fp-fmt-parse in Rust

Author: Oneirical

src/tools/run-make-support/src/rustc.rs

@@ -104,6 +104,13 @@ impl Rustc {
         self
     }
 
+    /// Generic file path provider.
+    pub fn arg_path(&mut self, path: &[&str]) -> &mut Self {
+        let path_buf = path.iter().collect::<PathBuf>();
+        self.cmd.arg(path_buf.to_str().unwrap());
+        self
+    }
+
     /// Generic command arguments provider. Use `.arg("-Zname")` over `.arg("-Z").arg("arg")`.
     /// This method will panic if a plain `-Z` or `-C` is passed, or if `-Z <name>` or `-C <name>`
     /// is passed (note the space).