From a857e6003e3f1ee1023bb8ec50cf652164bf5e11 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Sat, 10 Mar 2018 06:40:25 +0100
Subject: [PATCH] Make CodeMap thread-safe

---
 src/libsyntax/codemap.rs | 39 +++++++++++++++++----------------------
 1 file changed, 17 insertions(+), 22 deletions(-)

diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index 6a5a180fc0a74..829ba386d3528 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -24,8 +24,7 @@ pub use self::ExpnFormat::*;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::StableHasher;
-use rustc_data_structures::sync::Lrc;
-use std::cell::{RefCell, Ref};
+use rustc_data_structures::sync::{Lrc, Lock, LockGuard};
 use std::cmp;
 use std::hash::Hash;
 use std::path::{Path, PathBuf};
@@ -126,12 +125,12 @@ impl StableFilemapId {
 //
 
 pub struct CodeMap {
-    pub(super) files: RefCell<Vec<Lrc<FileMap>>>,
+    pub(super) files: Lock<Vec<Lrc<FileMap>>>,
     file_loader: Box<FileLoader + Sync + Send>,
     // This is used to apply the file path remapping as specified via
     // --remap-path-prefix to all FileMaps allocated within this CodeMap.
     path_mapping: FilePathMapping,
-    stable_id_to_filemap: RefCell<FxHashMap<StableFilemapId, Lrc<FileMap>>>,
+    stable_id_to_filemap: Lock<FxHashMap<StableFilemapId, Lrc<FileMap>>>,
     /// In case we are in a doctest, replace all file names with the PathBuf,
     /// and add the given offsets to the line info
     doctest_offset: Option<(FileName, isize)>,
@@ -140,10 +139,10 @@ pub struct CodeMap {
 impl CodeMap {
     pub fn new(path_mapping: FilePathMapping) -> CodeMap {
         CodeMap {
-            files: RefCell::new(Vec::new()),
+            files: Lock::new(Vec::new()),
             file_loader: Box::new(RealFileLoader),
             path_mapping,
-            stable_id_to_filemap: RefCell::new(FxHashMap()),
+            stable_id_to_filemap: Lock::new(FxHashMap()),
             doctest_offset: None,
         }
     }
@@ -161,10 +160,10 @@ impl CodeMap {
                             path_mapping: FilePathMapping)
                             -> CodeMap {
         CodeMap {
-            files: RefCell::new(Vec::new()),
-            file_loader,
+            files: Lock::new(Vec::new()),
+            file_loader: file_loader,
             path_mapping,
-            stable_id_to_filemap: RefCell::new(FxHashMap()),
+            stable_id_to_filemap: Lock::new(FxHashMap()),
             doctest_offset: None,
         }
     }
@@ -187,7 +186,7 @@ impl CodeMap {
         Ok(self.new_filemap(filename, src))
     }
 
-    pub fn files(&self) -> Ref<Vec<Lrc<FileMap>>> {
+    pub fn files(&self) -> LockGuard<Vec<Lrc<FileMap>>> {
         self.files.borrow()
     }
 
@@ -209,7 +208,6 @@ impl CodeMap {
     /// intend to set the line information yourself, you should use new_filemap_and_lines.
     pub fn new_filemap(&self, filename: FileName, src: String) -> Lrc<FileMap> {
         let start_pos = self.next_start_pos();
-        let mut files = self.files.borrow_mut();
 
         // The path is used to determine the directory for loading submodules and
         // include files, so it must be before remapping.
@@ -233,7 +231,7 @@ impl CodeMap {
             Pos::from_usize(start_pos),
         ));
 
-        files.push(filemap.clone());
+        self.files.borrow_mut().push(filemap.clone());
 
         self.stable_id_to_filemap
             .borrow_mut()
@@ -273,7 +271,6 @@ impl CodeMap {
                                 mut file_local_non_narrow_chars: Vec<NonNarrowChar>)
                                 -> Lrc<FileMap> {
         let start_pos = self.next_start_pos();
-        let mut files = self.files.borrow_mut();
 
         let end_pos = Pos::from_usize(start_pos + source_len);
         let start_pos = Pos::from_usize(start_pos);
@@ -297,16 +294,16 @@ impl CodeMap {
             crate_of_origin,
             src: None,
             src_hash,
-            external_src: RefCell::new(ExternalSource::AbsentOk),
+            external_src: Lock::new(ExternalSource::AbsentOk),
             start_pos,
             end_pos,
-            lines: RefCell::new(file_local_lines),
-            multibyte_chars: RefCell::new(file_local_multibyte_chars),
-            non_narrow_chars: RefCell::new(file_local_non_narrow_chars),
+            lines: Lock::new(file_local_lines),
+            multibyte_chars: Lock::new(file_local_multibyte_chars),
+            non_narrow_chars: Lock::new(file_local_non_narrow_chars),
             name_hash,
         });
 
-        files.push(filemap.clone());
+        self.files.borrow_mut().push(filemap.clone());
 
         self.stable_id_to_filemap
             .borrow_mut()
@@ -401,8 +398,7 @@ impl CodeMap {
     pub fn lookup_line(&self, pos: BytePos) -> Result<FileMapAndLine, Lrc<FileMap>> {
         let idx = self.lookup_filemap_idx(pos);
 
-        let files = self.files.borrow();
-        let f = (*files)[idx].clone();
+        let f = (*self.files.borrow())[idx].clone();
 
         match f.lookup_line(pos) {
             Some(line) => Ok(FileMapAndLine { fm: f, line: line }),
@@ -810,8 +806,7 @@ impl CodeMap {
     /// Converts an absolute BytePos to a CharPos relative to the filemap.
     pub fn bytepos_to_file_charpos(&self, bpos: BytePos) -> CharPos {
         let idx = self.lookup_filemap_idx(bpos);
-        let files = self.files.borrow();
-        let map = &(*files)[idx];
+        let map = &(*self.files.borrow())[idx];
 
         // The number of extra bytes due to multibyte chars in the FileMap
         let mut total_extra_bytes = 0;