Added source hashes to FileMap

We can use these to perform lazy loading of source files belonging to
external crates. That way we will be able to show the source code of
external spans that have been translated.

Author: ibabushkin

src/librustc/ich/impls_syntax.rs

@@ -336,6 +336,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for FileMa
             crate_of_origin,
             // Do not hash the source as it is not encoded
             src: _,
+            src_hash,
             start_pos,
             end_pos: _,
             ref lines,
@@ -350,6 +351,8 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for FileMa
             index: CRATE_DEF_INDEX,
         }.hash_stable(hcx, hasher);
 
+        src_hash.hash_stable(hcx, hasher);
+
         // We only hash the relative position within this filemap
         let lines = lines.borrow();
         lines.len().hash_stable(hcx, hasher);

src/librustc_metadata/decoder.rs

@@ -1148,6 +1148,7 @@ impl<'a, 'tcx> CrateMetadata {
             // containing the information we need.
             let syntax_pos::FileMap { name,
                                       name_was_remapped,
+                                      src_hash,
                                       start_pos,
                                       end_pos,
                                       lines,
@@ -1173,6 +1174,7 @@ impl<'a, 'tcx> CrateMetadata {
             let local_version = local_codemap.new_imported_filemap(name,
                                                                    name_was_remapped,
                                                                    self.cnum.as_u32(),
+                                                                   src_hash,
                                                                    source_length,
                                                                    lines,
                                                                    multibyte_chars);

src/libsyntax/codemap.rs

@@ -27,9 +27,12 @@ use std::rc::Rc;
 
 use std::env;
 use std::fs;
+use std::hash::Hasher;
 use std::io::{self, Read};
 use errors::CodeMapper;
 
+use rustc_data_structures::stable_hasher::StableHasher;
+
 /// Return the span itself if it doesn't come from a macro expansion,
 /// otherwise return the call site span up to the `enclosing_sp` by
 /// following the `expn_info` chain.
@@ -171,11 +174,16 @@ impl CodeMap {
 
         let (filename, was_remapped) = self.path_mapping.map_prefix(filename);
 
+        let mut hasher: StableHasher<u128> = StableHasher::new();
+        hasher.write(src.as_bytes());
+        let src_hash = hasher.finish();
+
         let filemap = Rc::new(FileMap {
             name: filename,
             name_was_remapped: was_remapped,
             crate_of_origin: 0,
             src: Some(Rc::new(src)),
+            src_hash: src_hash,
             start_pos: Pos::from_usize(start_pos),
             end_pos: Pos::from_usize(end_pos),
             lines: RefCell::new(Vec::new()),
@@ -210,6 +218,7 @@ impl CodeMap {
                                 filename: FileName,
                                 name_was_remapped: bool,
                                 crate_of_origin: u32,
+                                src_hash: u128,
                                 source_len: usize,
                                 mut file_local_lines: Vec<BytePos>,
                                 mut file_local_multibyte_chars: Vec<MultiByteChar>)
@@ -233,6 +242,7 @@ impl CodeMap {
             name_was_remapped: name_was_remapped,
             crate_of_origin: crate_of_origin,
             src: None,
+            src_hash: src_hash,
             start_pos: start_pos,
             end_pos: end_pos,
             lines: RefCell::new(file_local_lines),

src/libsyntax_pos/lib.rs

@@ -24,6 +24,7 @@
 
 #![feature(const_fn)]
 #![feature(custom_attribute)]
+#![feature(i128_type)]
 #![feature(optin_builtin_traits)]
 #![allow(unused_attributes)]
 #![feature(specialization)]
@@ -36,7 +37,6 @@ use std::cell::{Cell, RefCell};
 use std::ops::{Add, Sub};
 use std::rc::Rc;
 use std::cmp;
-
 use std::fmt;
 
 use serialize::{Encodable, Decodable, Encoder, Decoder};
@@ -382,6 +382,8 @@ pub struct FileMap {
     pub crate_of_origin: u32,
     /// The complete source code
     pub src: Option<Rc<String>>,
+    /// The source code's hash
+    pub src_hash: u128,
     /// The start position of this source in the CodeMap
     pub start_pos: BytePos,
     /// The end position of this source in the CodeMap
@@ -394,9 +396,10 @@ pub struct FileMap {
 
 impl Encodable for FileMap {
     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_struct("FileMap", 6, |s| {
+        s.emit_struct("FileMap", 7, |s| {
             s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
             s.emit_struct_field("name_was_remapped", 1, |s| self.name_was_remapped.encode(s))?;
+            s.emit_struct_field("src_hash", 6, |s| self.src_hash.encode(s))?;
             s.emit_struct_field("start_pos", 2, |s| self.start_pos.encode(s))?;
             s.emit_struct_field("end_pos", 3, |s| self.end_pos.encode(s))?;
             s.emit_struct_field("lines", 4, |s| {
@@ -459,7 +462,10 @@ impl Decodable for FileMap {
             let name: String = d.read_struct_field("name", 0, |d| Decodable::decode(d))?;
             let name_was_remapped: bool =
                 d.read_struct_field("name_was_remapped", 1, |d| Decodable::decode(d))?;
-            let start_pos: BytePos = d.read_struct_field("start_pos", 2, |d| Decodable::decode(d))?;
+            let src_hash: u128 =
+                d.read_struct_field("src_hash", 6, |d| Decodable::decode(d))?;
+            let start_pos: BytePos =
+                d.read_struct_field("start_pos", 2, |d| Decodable::decode(d))?;
             let end_pos: BytePos = d.read_struct_field("end_pos", 3, |d| Decodable::decode(d))?;
             let lines: Vec<BytePos> = d.read_struct_field("lines", 4, |d| {
                 let num_lines: u32 = Decodable::decode(d)?;
@@ -501,6 +507,7 @@ impl Decodable for FileMap {
                 start_pos: start_pos,
                 end_pos: end_pos,
                 src: None,
+                src_hash: src_hash,
                 lines: RefCell::new(lines),
                 multibyte_chars: RefCell::new(multibyte_chars)
             })