Allow supplying an error destination via the compiler driver

Allows replacing stderr with a buffer from the client.

Also, some refactoring around run_compiler.

1 files changed, 13 insertions, 3 deletions

diff --git a/src/libsyntax/json.rs b/src/libsyntax/json.rs
index a40c30b3e33..a1c273baeea 100644
--- a/src/libsyntax/json.rs
+++ b/src/libsyntax/json.rs
@@ -38,14 +38,24 @@ pub struct JsonEmitter {
 }
 
 impl JsonEmitter {
+    pub fn stderr(registry: Option<Registry>,
+                  code_map: Rc<CodeMap>) -> JsonEmitter {
+        JsonEmitter {
+            dst: Box::new(io::stderr()),
+            registry: registry,
+            cm: code_map,
+        }
+    }
+
     pub fn basic() -> JsonEmitter {
         JsonEmitter::stderr(None, Rc::new(CodeMap::new()))
     }
 
-    pub fn stderr(registry: Option<Registry>,
-                  code_map: Rc<CodeMap>) -> JsonEmitter {
+    pub fn new(dst: Box<Write + Send>,
+               registry: Option<Registry>,
+               code_map: Rc<CodeMap>) -> JsonEmitter {
         JsonEmitter {
-            dst: Box::new(io::stderr()),
+            dst: dst,
             registry: registry,
             cm: code_map,
         }