Move logic for making potentially remapped paths absolute into helper method.

Author: michaelwoerister

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -33,18 +33,14 @@ use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_serialize::{opaque, Encodable, Encoder};
 use rustc_session::config::CrateType;
 use rustc_session::cstore::{ForeignModule, LinkagePreference, NativeLib};
+use rustc_span::hygiene::{ExpnIndex, HygieneEncodeContext, MacroKind};
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{
     self, DebuggerVisualizerFile, ExternalSource, FileName, SourceFile, Span, SyntaxContext,
 };
-use rustc_span::{
-    hygiene::{ExpnIndex, HygieneEncodeContext, MacroKind},
-    RealFileName,
-};
 use rustc_target::abi::VariantIdx;
 use std::hash::Hash;
 use std::num::NonZeroUsize;
-use std::path::Path;
 use tracing::{debug, trace};
 
 pub(super) struct EncodeContext<'a, 'tcx> {
@@ -490,6 +486,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         // is done.
         let required_source_files = self.required_source_files.take().unwrap();
 
+        let working_directory = &self.tcx.sess.opts.working_dir;
+
         let adapted = all_source_files
             .iter()
             .enumerate()
@@ -502,76 +500,43 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 (!source_file.is_imported() || self.is_proc_macro)
             })
             .map(|(_, source_file)| {
-                let mut adapted = match source_file.name {
-                    FileName::Real(ref realname) => {
-                        let mut adapted = (**source_file).clone();
-                        adapted.name = FileName::Real(match realname {
-                            RealFileName::LocalPath(path_to_file) => {
-                                // Prepend path of working directory onto potentially
-                                // relative paths, because they could become relative
-                                // to a wrong directory.
-                                // We include `working_dir` as part of the crate hash,
-                                // so it's okay for us to use it as part of the encoded
-                                // metadata.
-                                let working_dir = &self.tcx.sess.opts.working_dir;
-                                match working_dir {
-                                    RealFileName::LocalPath(absolute) => {
-                                        // Although neither working_dir or the file name were subject
-                                        // to path remapping, the concatenation between the two may
-                                        // be. Hence we need to do a remapping here.
-                                        let joined = Path::new(absolute).join(path_to_file);
-                                        let (joined, remapped) =
-                                            source_map.path_mapping().map_prefix(joined);
-                                        if remapped {
-                                            RealFileName::Remapped {
-                                                local_path: None,
-                                                virtual_name: joined,
-                                            }
-                                        } else {
-                                            RealFileName::LocalPath(joined)
-                                        }
-                                    }
-                                    RealFileName::Remapped { local_path: _, virtual_name } => {
-                                        // If working_dir has been remapped, then we emit
-                                        // Remapped variant as the expanded path won't be valid
-                                        RealFileName::Remapped {
-                                            local_path: None,
-                                            virtual_name: Path::new(virtual_name)
-                                                .join(path_to_file),
-                                        }
-                                    }
-                                }
-                            }
-                            RealFileName::Remapped { local_path: _, virtual_name } => {
-                                RealFileName::Remapped {
-                                    // We do not want any local path to be exported into metadata
-                                    local_path: None,
-                                    virtual_name: virtual_name.clone(),
-                                }
-                            }
-                        });
-                        adapted.name_hash = {
-                            let mut hasher: StableHasher = StableHasher::new();
-                            adapted.name.hash(&mut hasher);
-                            hasher.finish::<u128>()
-                        };
-                        Lrc::new(adapted)
+                match source_file.name {
+                    FileName::Real(ref original_file_name) => {
+                        let adapted_file_name =
+                            source_map.path_mapping().to_embeddable_absolute_path(
+                                original_file_name.clone(),
+                                working_directory,
+                            );
+
+                        if adapted_file_name != *original_file_name {
+                            let mut adapted: SourceFile = (**source_file).clone();
+                            adapted.name = FileName::Real(adapted_file_name);
+                            adapted.name_hash = {
+                                let mut hasher: StableHasher = StableHasher::new();
+                                adapted.name.hash(&mut hasher);
+                                hasher.finish::<u128>()
+                            };
+                            Lrc::new(adapted)
+                        } else {
+                            // Nothing to adapt
+                            source_file.clone()
+                        }
                     }
-
                     // expanded code, not from a file
                     _ => source_file.clone(),
-                };
-
+                }
+            })
+            .map(|mut source_file| {
                 // We're serializing this `SourceFile` into our crate metadata,
                 // so mark it as coming from this crate.
                 // This also ensures that we don't try to deserialize the
                 // `CrateNum` for a proc-macro dependency - since proc macro
                 // dependencies aren't loaded when we deserialize a proc-macro,
                 // trying to remap the `CrateNum` would fail.
                 if self.is_proc_macro {
-                    Lrc::make_mut(&mut adapted).cnum = LOCAL_CRATE;
+                    Lrc::make_mut(&mut source_file).cnum = LOCAL_CRATE;
                 }
-                adapted
+                source_file
             })
             .collect::<Vec<_>>();
 

compiler/rustc_span/src/source_map.rs

@@ -1155,4 +1155,83 @@ impl FilePathMapping {
             other => (other.clone(), false),
         }
     }
+
+    /// Expand a relative path to an absolute path with remapping taken into account.
+    /// Use this when absolute paths are required (e.g. debuginfo or crate metadata).
+    ///
+    /// The resulting `RealFileName` will have its `local_path` portion erased if
+    /// possible (i.e. if there's also a remapped path).
+    pub fn to_embeddable_absolute_path(
+        &self,
+        file_path: RealFileName,
+        working_directory: &RealFileName,
+    ) -> RealFileName {
+        match file_path {
+            // Anything that's already remapped we don't modify, except for erasing
+            // the `local_path` portion.
+            RealFileName::Remapped { local_path: _, virtual_name } => {
+                RealFileName::Remapped {
+                    // We do not want any local path to be exported into metadata
+                    local_path: None,
+                    // We use the remapped name verbatim, even if it looks like a relative
+                    // path. The assumption is that the user doesn't want us to further
+                    // process paths that have gone through remapping.
+                    virtual_name,
+                }
+            }
+
+            RealFileName::LocalPath(unmapped_file_path) => {
+                // If no remapping has been applied yet, try to do so
+                let (new_path, was_remapped) = self.map_prefix(unmapped_file_path);
+                if was_remapped {
+                    // It was remapped, so don't modify further
+                    return RealFileName::Remapped { local_path: None, virtual_name: new_path };
+                }
+
+                if new_path.is_absolute() {
+                    // No remapping has applied to this path and it is absolute,
+                    // so the working directory cannot influence it either, so
+                    // we are done.
+                    return RealFileName::LocalPath(new_path);
+                }
+
+                debug_assert!(new_path.is_relative());
+                let unmapped_file_path_rel = new_path;
+
+                match working_directory {
+                    RealFileName::LocalPath(unmapped_working_dir_abs) => {
+                        let file_path_abs = unmapped_working_dir_abs.join(unmapped_file_path_rel);
+
+                        // Although neither `working_directory` nor the file name were subject
+                        // to path remapping, the concatenation between the two may be. Hence
+                        // we need to do a remapping here.
+                        let (file_path_abs, was_remapped) = self.map_prefix(file_path_abs);
+                        if was_remapped {
+                            RealFileName::Remapped {
+                                // Erase the actual path
+                                local_path: None,
+                                virtual_name: file_path_abs,
+                            }
+                        } else {
+                            // No kind of remapping applied to this path, so
+                            // we leave it as it is.
+                            RealFileName::LocalPath(file_path_abs)
+                        }
+                    }
+                    RealFileName::Remapped {
+                        local_path: _,
+                        virtual_name: remapped_working_dir_abs,
+                    } => {
+                        // If working_directory has been remapped, then we emit
+                        // Remapped variant as the expanded path won't be valid
+                        RealFileName::Remapped {
+                            local_path: None,
+                            virtual_name: Path::new(remapped_working_dir_abs)
+                                .join(unmapped_file_path_rel),
+                        }
+                    }
+                }
+            }
+        }
+    }
 }