Auto merge of #50997 - michaelwoerister:pre-analyze-filemaps, r=Mark-Simulacrum

 Make FileMap::{lines, multibyte_chars, non_narrow_chars} non-mutable.

This PR removes most of the interior mutability from `FileMap`, which should be beneficial, especially in a multithreaded setting. This is achieved by initializing the state in question when the filemap is constructed instead of during lexing. Hopefully this doesn't degrade performance.

cc @wesleywiser

2 files changed, 9 insertions, 5 deletions

diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 23880c1270f..9cd410d4243 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -1495,9 +1495,11 @@ impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 
                     match String::from_utf8(buf) {
                         Ok(src) => {
+                            let src_interned = Symbol::intern(&src);
+
                             // Add this input file to the code map to make it available as
                             // dependency information
-                            self.cx.codemap().new_filemap_and_lines(&filename, &src);
+                            self.cx.codemap().new_filemap(filename.into(), src);
 
                             let include_info = vec![
                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
@@ -1505,7 +1507,7 @@ impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
                                                                      dummy_spanned(file)))),
                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
                                         attr::mk_name_value_item_str(Ident::from_str("contents"),
-                                                            dummy_spanned(Symbol::intern(&src))))),
+                                                            dummy_spanned(src_interned)))),
                             ];
 
                             let include_ident = Ident::from_str("include");
diff --git a/src/libsyntax/ext/source_util.rs b/src/libsyntax/ext/source_util.rs
index d6dce63ea5e..669536f519c 100644
--- a/src/libsyntax/ext/source_util.rs
+++ b/src/libsyntax/ext/source_util.rs
@@ -150,11 +150,13 @@ pub fn expand_include_str(cx: &mut ExtCtxt, sp: Span, tts: &[tokenstream::TokenT
     };
     match String::from_utf8(bytes) {
         Ok(src) => {
+            let interned_src = Symbol::intern(&src);
+
             // Add this input file to the code map to make it available as
             // dependency information
-            cx.codemap().new_filemap_and_lines(&file, &src);
+            cx.codemap().new_filemap(file.into(), src);
 
-            base::MacEager::expr(cx.expr_str(sp, Symbol::intern(&src)))
+            base::MacEager::expr(cx.expr_str(sp, interned_src))
         }
         Err(_) => {
             cx.span_err(sp,
@@ -182,7 +184,7 @@ pub fn expand_include_bytes(cx: &mut ExtCtxt, sp: Span, tts: &[tokenstream::Toke
         Ok(..) => {
             // Add this input file to the code map to make it available as
             // dependency information, but don't enter it's contents
-            cx.codemap().new_filemap_and_lines(&file, "");
+            cx.codemap().new_filemap(file.into(), "".to_string());
 
             base::MacEager::expr(cx.expr_lit(sp, ast::LitKind::ByteStr(Lrc::new(bytes))))
         }