Retire Options::working_dir in favor SourceMap::working_dir

Only keep the local path to the working directory for incr comp and
directory users towards `SourceMap::working_dir` instead.

Author: Urgau

compiler/rustc_session/src/config.rs

@@ -1398,7 +1398,7 @@ impl Default for Options {
             json_unused_externs: JsonUnusedExterns::No,
             json_future_incompat: false,
             pretty: None,
-            working_dir: RealFileName::LocalPath(std::env::current_dir().unwrap()),
+            working_dir: std::env::current_dir().unwrap(),
             color: ColorConfig::Auto,
             logical_env: FxIndexMap::default(),
             verbose: false,
@@ -2756,9 +2756,6 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         early_dcx.early_fatal(format!("Current directory is invalid: {e}"));
     });
 
-    let file_mapping = file_path_mapping(remap_path_prefix.clone(), &unstable_opts);
-    let working_dir = file_mapping.to_real_filename(&working_dir);
-
     let verbose = matches.opt_present("verbose") || unstable_opts.verbose_internals;
 
     Options {

compiler/rustc_session/src/options.rs

@@ -491,8 +491,10 @@ top_level_options!(
 
         pretty: Option<PpMode> [UNTRACKED],
 
-        /// The (potentially remapped) working directory
-        working_dir: RealFileName [TRACKED],
+        /// The local working directory
+        #[rustc_lint_opt_deny_field_access("use `SourceMap::working_dir` instead of this field")]
+        working_dir: PathBuf [TRACKED],
+
         color: ColorConfig [UNTRACKED],
 
         verbose: bool [TRACKED_NO_CRATE_HASH],