Reduce the repetition in json error output

src/libsyntax/json.rs

@@ -153,17 +153,15 @@ impl Diagnostic {
     fn from_diagnostic_builder(db: &DiagnosticBuilder,
                                je: &JsonEmitter)
                                -> Diagnostic {
-        let sugg = db.suggestions.iter().flat_map(|sugg| {
-            je.render(sugg).into_iter().map(move |rendered| {
-                Diagnostic {
-                    message: sugg.msg.clone(),
-                    code: None,
-                    level: "help",
-                    spans: DiagnosticSpan::from_suggestion(sugg, je),
-                    children: vec![],
-                    rendered: Some(rendered),
-                }
-            })
+        let sugg = db.suggestions.iter().map(|sugg| {
+            Diagnostic {
+                message: sugg.msg.clone(),
+                code: None,
+                level: "help",
+                spans: DiagnosticSpan::from_suggestion(sugg, je),
+                children: vec![],
+                rendered: None,
+            }
         });
         Diagnostic {
             message: db.message(),
@@ -356,9 +354,3 @@ impl DiagnosticCode {
         })
     }
 }
-
-impl JsonEmitter {
-    fn render(&self, suggestion: &CodeSuggestion) -> Vec<String> {
-        suggestion.splice_lines(&*self.cm).iter().map(|line| line.0.to_owned()).collect()
-    }
-}

src/test/ui/lint/unused_parens_json_suggestion.stderr

@@ -1 +1 @@
-{"message":"unnecessary parentheses around assigned value","code":null,"level":"warning","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":976,"byte_end":989,"line_start":22,"line_end":22,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[{"message":"#[warn(unused_parens)] on by default","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"remove these parentheses","code":null,"level":"help","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":976,"byte_end":989,"line_start":22,"line_end":22,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":"1 / (2 + 3)","expansion":null}],"children":[],"rendered":"    let _a = 1 / (2 + 3);"}],"rendered":null}
+{"message":"unnecessary parentheses around assigned value","code":null,"level":"warning","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":976,"byte_end":989,"line_start":22,"line_end":22,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[{"message":"#[warn(unused_parens)] on by default","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"remove these parentheses","code":null,"level":"help","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":976,"byte_end":989,"line_start":22,"line_end":22,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":"1 / (2 + 3)","expansion":null}],"children":[],"rendered":null}],"rendered":null}