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.

src/librustc/ich/impls_syntax.rs

@@ -336,6 +336,7 @@ fn hash_stable<W: StableHasherResult>(&self,
             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 @@ fn hash_stable<W: StableHasherResult>(&self,
             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 @@ pub fn imported_filemaps(&'a self,
             // containing the information we need.
             let syntax_pos::FileMap { name,
                                       name_was_remapped,
+                                      src_hash,
                                       start_pos,
                                       end_pos,
                                       lines,
@@ -1173,6 +1174,7 @@ pub fn imported_filemaps(&'a self,
             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::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 @@ pub fn new_filemap(&self, filename: FileName, mut src: String) -> Rc<FileMap> {
 
         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 @@ pub fn new_imported_filemap(&self,
                                 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 @@ pub fn new_imported_filemap(&self,
             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::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 @@ fn decode<D: Decoder>(d: &mut D) -> Result<FileMap, D::Error> {
             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 @@ fn decode<D: Decoder>(d: &mut D) -> Result<FileMap, D::Error> {
                 start_pos: start_pos,
                 end_pos: end_pos,
                 src: None,
+                src_hash: src_hash,
                 lines: RefCell::new(lines),
                 multibyte_chars: RefCell::new(multibyte_chars)
             })