Auto merge of #83813 - cbeuw:remap-std, r=michaelwoerister

Fix `--remap-path-prefix` not correctly remapping `rust-src` component paths and unify handling of path mapping with virtualized paths

This PR fixes #73167 ("Binaries end up containing path to the rust-src component despite `--remap-path-prefix`") by preventing real local filesystem paths from reaching compilation output if the path is supposed to be remapped.

`RealFileName::Named` introduced in #72767 is now renamed as `LocalPath`, because this variant wraps a (most likely) valid local filesystem path.

`RealFileName::Devirtualized` is renamed as `Remapped` to be used for remapped path from a real path via `--remap-path-prefix` argument, as well as real path inferred from a virtualized (during compiler bootstrapping) `/rustc/...` path. The `local_path` field is now an `Option<PathBuf>`, as it will be set to `None` before serialisation, so it never reaches any build output. Attempting to serialise a non-`None` `local_path` will cause an assertion faliure.

When a path is remapped, a `RealFileName::Remapped` variant is created. The original path is preserved in `local_path` field and the remapped path is saved in `virtual_name` field. Previously, the `local_path` is directly modified which goes against its purpose of "suitable for reading from the file system on the local host".

`rustc_span::SourceFile`'s fields `unmapped_path` (introduced by #44940) and `name_was_remapped` (introduced by #41508 when `--remap-path-prefix` feature originally added) are removed, as these two pieces of information can be inferred from the `name` field: if it's anything other than a `FileName::Real(_)`, or if it is a `FileName::Real(RealFileName::LocalPath(_))`, then clearly `name_was_remapped` would've been false and `unmapped_path` would've been `None`. If it is a `FileName::Real(RealFileName::Remapped{local_path, virtual_name})`, then `name_was_remapped` would've been true and `unmapped_path` would've been `Some(local_path)`.

cc `@eddyb` who implemented `/rustc/...` path devirtualisation

compiler/rustc_builtin_macros/src/source_util.rs

@@ -61,7 +61,9 @@ pub fn expand_file(
 
     let topmost = cx.expansion_cause().unwrap_or(sp);
     let loc = cx.source_map().lookup_char_pos(topmost.lo());
-    base::MacEager::expr(cx.expr_str(topmost, Symbol::intern(&loc.file.name.to_string())))
+    base::MacEager::expr(
+        cx.expr_str(topmost, Symbol::intern(&loc.file.name.prefer_remapped().to_string_lossy())),
+    )
 }
 
 pub fn expand_stringify(

compiler/rustc_codegen_cranelift/src/common.rs

@@ -334,7 +334,9 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
         let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
         let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
         let const_loc = self.tcx.const_caller_location((
-            rustc_span::symbol::Symbol::intern(&caller.file.name.to_string()),
+            rustc_span::symbol::Symbol::intern(
+                &caller.file.name.prefer_remapped().to_string_lossy(),
+            ),
             caller.line as u32,
             caller.col_display as u32 + 1,
         ));

compiler/rustc_codegen_cranelift/src/debuginfo/line_info.rs

@@ -66,7 +66,7 @@ fn line_program_add_file(
 ) -> FileId {
     match &file.name {
         FileName::Real(path) => {
-            let (dir_path, file_name) = split_path_dir_and_file(path.stable_name());
+            let (dir_path, file_name) = split_path_dir_and_file(path.remapped_path_if_available());
             let dir_name = osstr_as_utf8_bytes(dir_path.as_os_str());
             let file_name = osstr_as_utf8_bytes(file_name);
 
@@ -87,7 +87,7 @@ fn line_program_add_file(
         filename => {
             let dir_id = line_program.default_directory();
             let dummy_file_name = LineString::new(
-                filename.to_string().into_bytes(),
+                filename.prefer_remapped().to_string().into_bytes(),
                 line_program.encoding(),
                 line_strings,
             );

compiler/rustc_codegen_cranelift/src/debuginfo/mod.rs

@@ -64,7 +64,7 @@ impl<'tcx> DebugContext<'tcx> {
         // FIXME: how to get version when building out of tree?
         // Normally this would use option_env!("CFG_VERSION").
         let producer = format!("cg_clif (rustc {})", "unknown version");
-        let comp_dir = tcx.sess.working_dir.0.to_string_lossy().into_owned();
+        let comp_dir = tcx.sess.working_dir.to_string_lossy(false).into_owned();
         let (name, file_info) = match tcx.sess.local_crate_source_file.clone() {
             Some(path) => {
                 let name = path.to_string_lossy().into_owned();

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -760,12 +760,12 @@ fn hex_encode(data: &[u8]) -> String {
 }
 
 pub fn file_metadata(cx: &CodegenCx<'ll, '_>, source_file: &SourceFile) -> &'ll DIFile {
-    debug!("file_metadata: file_name: {}", source_file.name);
+    debug!("file_metadata: file_name: {:?}", source_file.name);
 
     let hash = Some(&source_file.src_hash);
-    let file_name = Some(source_file.name.to_string());
+    let file_name = Some(source_file.name.prefer_remapped().to_string());
     let directory = if source_file.is_real_file() && !source_file.is_imported() {
-        Some(cx.sess().working_dir.0.to_string_lossy().to_string())
+        Some(cx.sess().working_dir.to_string_lossy(false).to_string())
     } else {
         // If the path comes from an upstream crate we assume it has been made
         // independent of the compiler's working directory one way or another.
@@ -993,7 +993,7 @@ pub fn compile_unit_metadata(
     let producer = format!("clang LLVM ({})", rustc_producer);
 
     let name_in_debuginfo = name_in_debuginfo.to_string_lossy();
-    let work_dir = tcx.sess.working_dir.0.to_string_lossy();
+    let work_dir = tcx.sess.working_dir.to_string_lossy(false);
     let flags = "\0";
     let out_dir = &tcx.output_filenames(LOCAL_CRATE).out_directory;
     let split_name = if tcx.sess.target_can_use_split_dwarf() {

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1144,7 +1144,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
             let caller = tcx.sess.source_map().lookup_char_pos(topmost.lo());
             let const_loc = tcx.const_caller_location((
-                Symbol::intern(&caller.file.name.to_string()),
+                Symbol::intern(&caller.file.name.prefer_remapped().to_string_lossy()),
                 caller.line as u32,
                 caller.col_display as u32 + 1,
             ));

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -126,7 +126,8 @@ impl AnnotateSnippetEmitterWriter {
             }
             // owned: line source, line index, annotations
             type Owned = (String, usize, Vec<crate::snippet::Annotation>);
-            let origin = primary_lo.file.name.to_string();
+            let filename = primary_lo.file.name.prefer_local();
+            let origin = filename.to_string_lossy();
             let annotated_files: Vec<Owned> = annotated_files
                 .into_iter()
                 .flat_map(|annotated_file| {

compiler/rustc_errors/src/emitter.rs

@@ -1324,7 +1324,7 @@ impl EmitterWriter {
                         buffer_msg_line_offset,
                         &format!(
                             "{}:{}:{}",
-                            loc.file.name,
+                            loc.file.name.prefer_local(),
                             sm.doctest_offset_line(&loc.file.name, loc.line),
                             loc.col.0 + 1,
                         ),
@@ -1338,7 +1338,7 @@ impl EmitterWriter {
                         0,
                         &format!(
                             "{}:{}:{}: ",
-                            loc.file.name,
+                            loc.file.name.prefer_local(),
                             sm.doctest_offset_line(&loc.file.name, loc.line),
                             loc.col.0 + 1,
                         ),
@@ -1362,12 +1362,12 @@ impl EmitterWriter {
                     };
                     format!(
                         "{}:{}{}",
-                        annotated_file.file.name,
+                        annotated_file.file.name.prefer_local(),
                         sm.doctest_offset_line(&annotated_file.file.name, first_line.line_index),
                         col
                     )
                 } else {
-                    annotated_file.file.name.to_string()
+                    format!("{}", annotated_file.file.name.prefer_local())
                 };
                 buffer.append(buffer_msg_line_offset + 1, &loc, Style::LineAndColumn);
                 for _ in 0..max_line_num_len {

compiler/rustc_errors/src/json.rs

@@ -468,7 +468,7 @@ impl DiagnosticSpan {
         });
 
         DiagnosticSpan {
-            file_name: start.file.name.to_string(),
+            file_name: start.file.name.prefer_local().to_string(),
             byte_start: start.file.original_relative_byte_pos(span.lo()).0,
             byte_end: start.file.original_relative_byte_pos(span.hi()).0,
             line_start: start.line,

compiler/rustc_expand/src/base.rs

@@ -1084,13 +1084,18 @@ impl<'a> ExtCtxt<'a> {
         // after macro expansion (that is, they are unhygienic).
         if !path.is_absolute() {
             let callsite = span.source_callsite();
-            let mut result = match self.source_map().span_to_unmapped_path(callsite) {
-                FileName::Real(name) => name.into_local_path(),
+            let mut result = match self.source_map().span_to_filename(callsite) {
+                FileName::Real(name) => name
+                    .into_local_path()
+                    .expect("attempting to resolve a file path in an external file"),
                 FileName::DocTest(path, _) => path,
                 other => {
                     return Err(self.struct_span_err(
                         span,
-                        &format!("cannot resolve relative path in non-file source `{}`", other),
+                        &format!(
+                            "cannot resolve relative path in non-file source `{}`",
+                            other.prefer_local()
+                        ),
                     ));
                 }
             };

compiler/rustc_expand/src/expand.rs

@@ -361,9 +361,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
     // FIXME: Avoid visiting the crate as a `Mod` item,
     // make crate a first class expansion target instead.
     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
-        let file_path = match self.cx.source_map().span_to_unmapped_path(krate.span) {
-            FileName::Real(name) => name.into_local_path(),
-            other => PathBuf::from(other.to_string()),
+        let file_path = match self.cx.source_map().span_to_filename(krate.span) {
+            FileName::Real(name) => name
+                .into_local_path()
+                .expect("attempting to resolve a file path in an external file"),
+            other => PathBuf::from(other.prefer_local().to_string()),
         };
         let dir_path = file_path.parent().unwrap_or(&file_path).to_owned();
         self.cx.root_path = dir_path.clone();

compiler/rustc_expand/src/proc_macro_server.rs

@@ -638,10 +638,11 @@ impl server::SourceFile for Rustc<'_> {
         match file.name {
             FileName::Real(ref name) => name
                 .local_path()
+                .expect("attempting to get a file path in an imported file in `proc_macro::SourceFile::path`")
                 .to_str()
                 .expect("non-UTF8 file path in `proc_macro::SourceFile::path`")
                 .to_string(),
-            _ => file.name.to_string(),
+            _ => file.name.prefer_local().to_string(),
         }
     }
     fn is_real(&mut self, file: &Self::SourceFile) -> bool {
@@ -785,7 +786,7 @@ fn ident_name_compatibility_hack(
         if let ExpnKind::Macro { name: macro_name, .. } = orig_span.ctxt().outer_expn_data().kind {
             let source_map = rustc.sess.source_map();
             let filename = source_map.span_to_filename(orig_span);
-            if let FileName::Real(RealFileName::Named(path)) = filename {
+            if let FileName::Real(RealFileName::LocalPath(path)) = filename {
                 let matches_prefix = |prefix, filename| {
                     // Check for a path that ends with 'prefix*/src/<filename>'
                     let mut iter = path.components().rev();
@@ -848,7 +849,7 @@ fn ident_name_compatibility_hack(
                 if macro_name == sym::tuple_from_req && matches_prefix("actix-web", "extract.rs") {
                     let snippet = source_map.span_to_snippet(orig_span);
                     if snippet.as_deref() == Ok("$T") {
-                        if let FileName::Real(RealFileName::Named(macro_path)) =
+                        if let FileName::Real(RealFileName::LocalPath(macro_path)) =
                             source_map.span_to_filename(rustc.def_site)
                         {
                             if macro_path.to_string_lossy().contains("pin-project-internal-0.") {

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1604,13 +1604,19 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             match (&terr, expected == found) {
                 (TypeError::Sorts(values), extra) => {
                     let sort_string = |ty: Ty<'tcx>| match (extra, ty.kind()) {
-                        (true, ty::Opaque(def_id, _)) => format!(
-                            " (opaque type at {})",
-                            self.tcx
+                        (true, ty::Opaque(def_id, _)) => {
+                            let pos = self
+                                .tcx
                                 .sess
                                 .source_map()
-                                .mk_substr_filename(self.tcx.def_span(*def_id)),
-                        ),
+                                .lookup_char_pos(self.tcx.def_span(*def_id).lo());
+                            format!(
+                                " (opaque type at <{}:{}:{}>)",
+                                pos.file.name.prefer_local(),
+                                pos.line,
+                                pos.col.to_usize() + 1,
+                            )
+                        }
                         (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
                         (false, _) => "".to_string(),
                     };

compiler/rustc_interface/src/passes.rs

@@ -35,7 +35,6 @@ use rustc_session::output::{filename_for_input, filename_for_metadata};
 use rustc_session::search_paths::PathKind;
 use rustc_session::Session;
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_span::{FileName, RealFileName};
 use rustc_trait_selection::traits;
 use rustc_typeck as typeck;
 use tracing::{info, warn};
@@ -531,10 +530,10 @@ fn output_conflicts_with_dir(output_paths: &[PathBuf]) -> Option<PathBuf> {
     check_output(output_paths, check)
 }
 
-fn escape_dep_filename(filename: &FileName) -> String {
+fn escape_dep_filename(filename: &String) -> String {
     // Apparently clang and gcc *only* escape spaces:
     // http://llvm.org/klaus/clang/commit/9d50634cfc268ecc9a7250226dd5ca0e945240d4
-    filename.to_string().replace(" ", "\\ ")
+    filename.replace(" ", "\\ ")
 }
 
 // Makefile comments only need escaping newlines and `\`.
@@ -574,7 +573,7 @@ fn write_out_deps(
             .iter()
             .filter(|fmap| fmap.is_real_file())
             .filter(|fmap| !fmap.is_imported())
-            .map(|fmap| escape_dep_filename(&fmap.unmapped_path.as_ref().unwrap_or(&fmap.name)))
+            .map(|fmap| escape_dep_filename(&fmap.name.prefer_local().to_string()))
             .collect();
 
         if let Some(ref backend) = sess.opts.debugging_opts.codegen_backend {
@@ -586,16 +585,13 @@ fn write_out_deps(
                 for cnum in resolver.cstore().crates_untracked() {
                     let source = resolver.cstore().crate_source_untracked(cnum);
                     if let Some((path, _)) = source.dylib {
-                        let file_name = FileName::Real(RealFileName::Named(path));
-                        files.push(escape_dep_filename(&file_name));
+                        files.push(escape_dep_filename(&path.display().to_string()));
                     }
                     if let Some((path, _)) = source.rlib {
-                        let file_name = FileName::Real(RealFileName::Named(path));
-                        files.push(escape_dep_filename(&file_name));
+                        files.push(escape_dep_filename(&path.display().to_string()));
                     }
                     if let Some((path, _)) = source.rmeta {
-                        let file_name = FileName::Real(RealFileName::Named(path));
-                        files.push(escape_dep_filename(&file_name));
+                        files.push(escape_dep_filename(&path.display().to_string()));
                     }
                 }
             });

compiler/rustc_interface/src/tests.rs

@@ -724,6 +724,7 @@ fn test_debugging_options_tracking_hash() {
     tracked!(profile_emit, Some(PathBuf::from("abc")));
     tracked!(relax_elf_relocations, Some(true));
     tracked!(relro_level, Some(RelroLevel::Full));
+    tracked!(simulate_remapped_rust_src_base, Some(PathBuf::from("/rustc/abc")));
     tracked!(report_delayed_bugs, true);
     tracked!(sanitizer, SanitizerSet::ADDRESS);
     tracked!(sanitizer_memory_track_origins, 2);

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1651,9 +1651,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             if let Some(virtual_dir) = virtual_rust_source_base_dir {
                 if let Some(real_dir) = &sess.opts.real_rust_source_base_dir {
                     if let rustc_span::FileName::Real(old_name) = name {
-                        if let rustc_span::RealFileName::Named(one_path) = old_name {
-                            if let Ok(rest) = one_path.strip_prefix(virtual_dir) {
-                                let virtual_name = one_path.clone();
+                        if let rustc_span::RealFileName::Remapped { local_path: _, virtual_name } =
+                            old_name
+                        {
+                            if let Ok(rest) = virtual_name.strip_prefix(virtual_dir) {
+                                let virtual_name = virtual_name.clone();
 
                                 // The std library crates are in
                                 // `$sysroot/lib/rustlib/src/rust/library`, whereas other crates
@@ -1689,8 +1691,8 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                                     virtual_name.display(),
                                     new_path.display(),
                                 );
-                                let new_name = rustc_span::RealFileName::Devirtualized {
-                                    local_path: new_path,
+                                let new_name = rustc_span::RealFileName::Remapped {
+                                    local_path: Some(new_path),
                                     virtual_name,
                                 };
                                 *old_name = new_name;
@@ -1710,7 +1712,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                     // containing the information we need.
                     let rustc_span::SourceFile {
                         mut name,
-                        name_was_remapped,
                         src_hash,
                         start_pos,
                         end_pos,
@@ -1722,11 +1723,34 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                         ..
                     } = source_file_to_import;
 
+                    // If this file is under $sysroot/lib/rustlib/src/ but has not been remapped
+                    // during rust bootstrapping by `remap-debuginfo = true`, and the user
+                    // wish to simulate that behaviour by -Z simulate-remapped-rust-src-base,
+                    // then we change `name` to a similar state as if the rust was bootstrapped
+                    // with `remap-debuginfo = true`.
+                    // This is useful for testing so that tests about the effects of
+                    // `try_to_translate_virtual_to_real` don't have to worry about how the
+                    // compiler is bootstrapped.
+                    if let Some(virtual_dir) =
+                        &sess.opts.debugging_opts.simulate_remapped_rust_src_base
+                    {
+                        if let Some(real_dir) = &sess.opts.real_rust_source_base_dir {
+                            if let rustc_span::FileName::Real(ref mut old_name) = name {
+                                if let rustc_span::RealFileName::LocalPath(local) = old_name {
+                                    if let Ok(rest) = local.strip_prefix(real_dir) {
+                                        *old_name = rustc_span::RealFileName::Remapped {
+                                            local_path: None,
+                                            virtual_name: virtual_dir.join(rest),
+                                        };
+                                    }
+                                }
+                            }
+                        }
+                    }
+
                     // If this file's path has been remapped to `/rustc/$hash`,
                     // we might be able to reverse that (also see comments above,
                     // on `try_to_translate_virtual_to_real`).
-                    // FIXME(eddyb) we could check `name_was_remapped` here,
-                    // but in practice it seems to be always `false`.
                     try_to_translate_virtual_to_real(&mut name);
 
                     let source_length = (end_pos - start_pos).to_usize();
@@ -1751,7 +1775,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
 
                     let local_version = sess.source_map().new_imported_source_file(
                         name,
-                        name_was_remapped,
                         src_hash,
                         name_hash,
                         source_length,