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_mir/src/borrow_check/region_infer/dump_mir.rs

@@ -76,7 +76,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         for constraint in &constraints {
             let OutlivesConstraint { sup, sub, locations, category } = constraint;
             let (name, arg) = match locations {
-                Locations::All(span) => ("All", tcx.sess.source_map().span_to_string(*span)),
+                Locations::All(span) => {
+                    ("All", tcx.sess.source_map().span_to_embeddable_string(*span))
+                }
                 Locations::Single(loc) => ("Single", format!("{:?}", loc)),
             };
             with_msg(&format!("{:?}: {:?} due to {:?} at {}({})", sup, sub, category, name, arg))?;

compiler/rustc_mir/src/interpret/eval_context.rs

@@ -263,7 +263,13 @@ impl<'tcx> fmt::Display for FrameInfo<'tcx> {
             }
             if !self.span.is_dummy() {
                 let lo = tcx.sess.source_map().lookup_char_pos(self.span.lo());
-                write!(f, " at {}:{}:{}", lo.file.name, lo.line, lo.col.to_usize() + 1)?;
+                write!(
+                    f,
+                    " at {}:{}:{}",
+                    lo.file.name.prefer_local(),
+                    lo.line,
+                    lo.col.to_usize() + 1
+                )?;
             }
             Ok(())
         })

compiler/rustc_mir/src/interpret/intrinsics/caller_location.rs

@@ -106,7 +106,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
         let caller = self.tcx.sess.source_map().lookup_char_pos(topmost.lo());
         (
-            Symbol::intern(&caller.file.name.to_string()),
+            Symbol::intern(&caller.file.name.prefer_remapped().to_string_lossy()),
             u32::try_from(caller.line).unwrap(),
             u32::try_from(caller.col_display).unwrap().checked_add(1).unwrap(),
         )

compiler/rustc_mir/src/transform/coverage/mod.rs

@@ -169,8 +169,8 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
         debug!(
             "instrumenting {:?}, fn sig span: {}, body span: {}",
             def_id,
-            source_map.span_to_string(fn_sig_span),
-            source_map.span_to_string(body_span)
+            source_map.span_to_diagnostic_string(fn_sig_span),
+            source_map.span_to_diagnostic_string(body_span)
         );
 
         let mut graphviz_data = debug::GraphvizData::new();
@@ -311,7 +311,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
         let tcx = self.tcx;
         let source_map = tcx.sess.source_map();
         let body_span = self.body_span;
-        let file_name = Symbol::intern(&self.source_file.name.to_string());
+        let file_name = Symbol::intern(&self.source_file.name.prefer_remapped().to_string_lossy());
 
         let mut bcb_counters = IndexVec::from_elem_n(None, self.basic_coverage_blocks.num_nodes());
         for covspan in coverage_spans {
@@ -332,8 +332,8 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                 "Calling make_code_region(file_name={}, source_file={:?}, span={}, body_span={})",
                 file_name,
                 self.source_file,
-                source_map.span_to_string(span),
-                source_map.span_to_string(body_span)
+                source_map.span_to_diagnostic_string(span),
+                source_map.span_to_diagnostic_string(body_span)
             );
 
             inject_statement(

compiler/rustc_mir/src/util/pretty.rs

@@ -445,7 +445,10 @@ impl Visitor<'tcx> for ExtraComments<'tcx> {
             ty::Tuple(tys) if tys.is_empty() => {}
             _ => {
                 self.push("mir::Constant");
-                self.push(&format!("+ span: {}", self.tcx.sess.source_map().span_to_string(*span)));
+                self.push(&format!(
+                    "+ span: {}",
+                    self.tcx.sess.source_map().span_to_embeddable_string(*span)
+                ));
                 if let Some(user_ty) = user_ty {
                     self.push(&format!("+ user_ty: {:?}", user_ty));
                 }
@@ -516,7 +519,7 @@ impl Visitor<'tcx> for ExtraComments<'tcx> {
 }
 
 fn comment(tcx: TyCtxt<'_>, SourceInfo { span, scope }: SourceInfo) -> String {
-    format!("scope {} at {}", scope.index(), tcx.sess.source_map().span_to_string(span))
+    format!("scope {} at {}", scope.index(), tcx.sess.source_map().span_to_embeddable_string(span))
 }
 
 /// Prints local variables in a scope tree.
@@ -617,7 +620,7 @@ fn write_scope_tree(
                 "{0:1$} // at {2}",
                 indented_header,
                 ALIGN,
-                tcx.sess.source_map().span_to_string(span),
+                tcx.sess.source_map().span_to_embeddable_string(span),
             )?;
         } else {
             writeln!(w, "{}", indented_header)?;
@@ -1004,7 +1007,7 @@ fn write_user_type_annotations(
             "| {:?}: {:?} at {}",
             index.index(),
             annotation.user_ty,
-            tcx.sess.source_map().span_to_string(annotation.span)
+            tcx.sess.source_map().span_to_embeddable_string(annotation.span)
         )?;
     }
     if !body.user_type_annotations.is_empty() {

compiler/rustc_mir/src/util/spanview.rs

@@ -628,7 +628,7 @@ fn tooltip<'tcx>(
 ) -> String {
     let source_map = tcx.sess.source_map();
     let mut text = Vec::new();
-    text.push(format!("{}: {}:", spanview_id, &source_map.span_to_string(span)));
+    text.push(format!("{}: {}:", spanview_id, &source_map.span_to_embeddable_string(span)));
     for statement in statements {
         let source_range = source_range_no_file(tcx, &statement.source_info.span);
         text.push(format!(