Implement debuginfo path remapping

src/librustc/session/config.rs

@@ -253,6 +253,7 @@ top_level_options!(
         // Include the debug_assertions flag into dependency tracking, since it
         // can influence whether overflow checks are done or not.
         debug_assertions: bool [TRACKED],
+        debug_prefix_map: Option<(String, String)> [TRACKED],
         debuginfo: DebugInfoLevel [TRACKED],
         lint_opts: Vec<(String, lint::Level)> [TRACKED],
         lint_cap: Option<lint::Level> [TRACKED],
@@ -445,6 +446,7 @@ pub fn basic_options() -> Options {
         libs: Vec::new(),
         unstable_features: UnstableFeatures::Disallow,
         debug_assertions: true,
+        debug_prefix_map: None,
         actually_rustdoc: false,
     }
 }
@@ -801,6 +803,8 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
         "optimize with possible levels 0-3, s, or z"),
     debug_assertions: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "explicitly enable the cfg(debug_assertions) directive"),
+    debug_prefix_map: String = ("".to_string(), parse_string, [TRACKED],
+        "remap OLD to NEW in debug info (OLD=NEW)"),
     inline_threshold: Option<usize> = (None, parse_opt_uint, [TRACKED],
         "set the inlining threshold for"),
     panic: Option<PanicStrategy> = (None, parse_panic_strategy,
@@ -1423,6 +1427,20 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
         }
     };
     let debug_assertions = cg.debug_assertions.unwrap_or(opt_level == OptLevel::No);
+
+    let debug_prefix_map = if !cg.debug_prefix_map.is_empty() {
+        let mut parts = cg.debug_prefix_map.splitn(2, '=');
+        let old = parts.next().unwrap();
+        let new = match parts.next() {
+            Some(new) => new,
+            None => early_error(error_format,
+                                "-C debug-prefix-map value must be of the format `OLD=NEW`"),
+        };
+        Some((old.to_string(), new.to_string()))
+    } else {
+        None
+    };
+
     let debuginfo = if matches.opt_present("g") {
         if cg.debuginfo.is_some() {
             early_error(error_format, "-g and -C debuginfo both provided");
@@ -1539,6 +1557,7 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
         libs: libs,
         unstable_features: UnstableFeatures::from_environment(),
         debug_assertions: debug_assertions,
+        debug_prefix_map: debug_prefix_map,
         actually_rustdoc: false,
     },
     cfg)
@@ -1714,6 +1733,7 @@ mod dep_tracking {
     impl_dep_tracking_hash_via_hash!(Option<bool>);
     impl_dep_tracking_hash_via_hash!(Option<usize>);
     impl_dep_tracking_hash_via_hash!(Option<String>);
+    impl_dep_tracking_hash_via_hash!(Option<(String, String)>);
     impl_dep_tracking_hash_via_hash!(Option<PanicStrategy>);
     impl_dep_tracking_hash_via_hash!(Option<lint::Level>);
     impl_dep_tracking_hash_via_hash!(Option<PathBuf>);

src/librustc_trans/debuginfo/metadata.rs

@@ -657,6 +657,15 @@ pub fn type_metadata<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
     metadata
 }
 
+fn remap_path(sess: &Session, path: &str) -> String {
+    for (old, new) in sess.opts.debug_prefix_map.clone() {
+        if path.starts_with(&old) {
+            return new + &path[old.len()..];
+        }
+    }
+    path.to_string()
+}
+
 pub fn file_metadata(cx: &CrateContext, path: &str, full_path: &Option<String>) -> DIFile {
     // FIXME (#9639): This needs to handle non-utf8 paths
     let work_dir = cx.sess().working_dir.to_str().unwrap();
@@ -669,7 +678,10 @@ pub fn file_metadata(cx: &CrateContext, path: &str, full_path: &Option<String>)
             }
         });
 
-    file_metadata_(cx, path, file_name, &work_dir)
+    let sess = cx.sess();
+    let remap_file_name = remap_path(sess, file_name);
+    let remap_dir = remap_path(sess, work_dir);
+    file_metadata_(cx, path, &remap_file_name, &remap_dir)
 }
 
 pub fn unknown_file_metadata(cx: &CrateContext) -> DIFile {
@@ -759,7 +771,7 @@ pub fn compile_unit_metadata(scc: &SharedCrateContext,
                              debug_context: &CrateDebugContext,
                              sess: &Session)
                              -> DIDescriptor {
-    let work_dir = &sess.working_dir;
+    let work_dir = sess.working_dir.to_str().unwrap();
     let compile_unit_name = match sess.local_crate_source_file {
         None => fallback_path(scc),
         Some(ref abs_path) => {
@@ -781,12 +793,14 @@ pub fn compile_unit_metadata(scc: &SharedCrateContext,
         }
     };
 
+    let work_dir = remap_path(sess, work_dir);
+
     debug!("compile_unit_metadata: {:?}", compile_unit_name);
     let producer = format!("rustc version {}",
                            (option_env!("CFG_VERSION")).expect("CFG_VERSION"));
 
     let compile_unit_name = compile_unit_name.as_ptr();
-    let work_dir = path2cstr(&work_dir);
+    let work_dir = CString::new(work_dir).unwrap();
     let producer = CString::new(producer).unwrap();
     let flags = "\0";
     let split_name = "\0";