Fix path slashes on Windows

src/main.rs

@@ -262,8 +262,7 @@ fn list_files(tool: &dyn Tool, source: &Utf8Path, options: &Options, json: bool)
                 .iter()
                 .map(|source_file| {
                     json!({
-                        // to_string so that we get it with slashes.
-                        "path": source_file.tree_relative_path.to_string(),
+                        "path": source_file.tree_relative_path.to_slash_path(),
                         "package": source_file.package.name,
                     })
                 })
@@ -273,7 +272,7 @@ fn list_files(tool: &dyn Tool, source: &Utf8Path, options: &Options, json: bool)
         writeln!(out)?;
     } else {
         for file in files {
-            writeln!(out, "{}", file.tree_relative_path)?;
+            writeln!(out, "{}", file.tree_relative_path.to_slash_path())?;
         }
     }
     Ok(())

src/source.rs

@@ -9,6 +9,8 @@ use camino::{Utf8Path, Utf8PathBuf};
 #[allow(unused_imports)]
 use tracing::{debug, info, warn};
 
+use crate::path::Utf8PathSlashes;
+
 /// A Rust source file within a source tree.
 ///
 /// It can be viewed either relative to the source tree (for display)
@@ -50,7 +52,7 @@ impl SourceFile {
 
     /// Return the path of this file relative to the tree root, with forward slashes.
     pub fn tree_relative_slashes(&self) -> String {
-        self.tree_relative_path.to_string()
+        self.tree_relative_path.to_slash_path()
     }
 
     /// Return the path of this file relative to the base of the source tree.