Rollup of 4 pull requests

src/librustc_ast/ast.rs

@@ -2211,14 +2211,14 @@ rustc_index::newtype_index! {
 }
 
 impl rustc_serialize::Encodable for AttrId {
-    fn encode<S: Encoder>(&self, _: &mut S) -> Result<(), S::Error> {
-        Ok(())
+    fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
+        s.emit_unit()
     }
 }
 
 impl rustc_serialize::Decodable for AttrId {
-    fn decode<D: Decoder>(_: &mut D) -> Result<AttrId, D::Error> {
-        Ok(crate::attr::mk_attr_id())
+    fn decode<D: Decoder>(d: &mut D) -> Result<AttrId, D::Error> {
+        d.read_nil().map(|_| crate::attr::mk_attr_id())
     }
 }
 

src/test/ui/ast-json/ast-json-noexpand-output.rs

@@ -0,0 +1,10 @@
+// Check that AST json printing works.
+#![crate_type = "lib"]
+
+// check-pass
+// compile-flags: -Zast-json-noexpand
+// normalize-stdout-test ":\d+" -> ":0"
+
+// Only include a single item to reduce how often the test output needs
+// updating.
+extern crate core;

src/test/ui/ast-json/ast-json-noexpand-output.stdout

@@ -0,0 +1 @@
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src/test/ui/ast-json/ast-json-output.rs

@@ -1,7 +1,8 @@
 // Check that AST json printing works.
+#![crate_type = "lib"]
 
 // check-pass
-// compile-flags: -Zast-json-noexpand
+// compile-flags: -Zast-json
 // normalize-stdout-test ":\d+" -> ":0"
 
 // Only include a single item to reduce how often the test output needs

src/test/ui/ast-json/ast-json-output.stdout

@@ -1 +1 @@
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