Pretty print json in ui tests

src/librustc/session/config.rs

@@ -155,7 +155,7 @@ impl OutputType {
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum ErrorOutputType {
     HumanReadable(ColorConfig),
-    Json,
+    Json(bool),
     Short(ColorConfig),
 }
 
@@ -1104,6 +1104,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "enable ThinLTO when possible"),
     inline_in_all_cgus: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "control whether #[inline] functions are in all cgus"),
+    pretty_json_error_format: bool = (false, parse_bool, [UNTRACKED],
+          "allow `--error-format=pretty-json` (used for compiletest)"),
 }
 
 pub fn default_lib_output() -> CrateType {
@@ -1433,7 +1435,8 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
     let error_format = if matches.opts_present(&["error-format".to_owned()]) {
         match matches.opt_str("error-format").as_ref().map(|s| &s[..]) {
             Some("human") => ErrorOutputType::HumanReadable(color),
-            Some("json")  => ErrorOutputType::Json,
+            Some("json")  => ErrorOutputType::Json(false),
+            Some("pretty-json") => ErrorOutputType::Json(true),
             Some("short") => ErrorOutputType::Short(color),
 
             None => ErrorOutputType::HumanReadable(color),
@@ -1474,6 +1477,11 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
 
     let debugging_opts = build_debugging_options(matches, error_format);
 
+    if !debugging_opts.pretty_json_error_format && error_format == ErrorOutputType::Json(true) {
+        early_error(ErrorOutputType::Json(false), "--error-format=pretty-json is unstable \
+                                                   (use -Zpretty-json-error-format)");
+    }
+
     let mut output_types = BTreeMap::new();
     if !debugging_opts.parse_only {
         for list in matches.opt_strs("emit") {

src/librustc/session/mod.rs

@@ -372,7 +372,7 @@ impl Session {
         match self.opts.error_format {
             // when outputting JSON for tool consumption, the tool might want
             // the duplicates
-            config::ErrorOutputType::Json => {
+            config::ErrorOutputType::Json(_) => {
                 do_method()
             },
             _ => {
@@ -736,11 +736,11 @@ pub fn build_session_with_codemap(sopts: config::Options,
         (config::ErrorOutputType::HumanReadable(_), Some(dst)) => {
             Box::new(EmitterWriter::new(dst, Some(codemap.clone()), false))
         }
-        (config::ErrorOutputType::Json, None) => {
+        (config::ErrorOutputType::Json(pretty), None) => {
-            Box::new(JsonEmitter::stderr(Some(registry), codemap.clone()))
+            Box::new(JsonEmitter::stderr(Some(registry), codemap.clone(), pretty))
         }
-        (config::ErrorOutputType::Json, Some(dst)) => {
+        (config::ErrorOutputType::Json(pretty), Some(dst)) => {
-            Box::new(JsonEmitter::new(dst, Some(registry), codemap.clone()))
+            Box::new(JsonEmitter::new(dst, Some(registry), codemap.clone(), pretty))
         }
         (config::ErrorOutputType::Short(color_config), None) => {
             Box::new(EmitterWriter::stderr(color_config, Some(codemap.clone()), true))
@@ -918,7 +918,7 @@ pub fn early_error(output: config::ErrorOutputType, msg: &str) -> ! {
         config::ErrorOutputType::HumanReadable(color_config) => {
             Box::new(EmitterWriter::stderr(color_config, None, false))
         }
-        config::ErrorOutputType::Json => Box::new(JsonEmitter::basic()),
+        config::ErrorOutputType::Json(pretty) => Box::new(JsonEmitter::basic(pretty)),
         config::ErrorOutputType::Short(color_config) => {
             Box::new(EmitterWriter::stderr(color_config, None, true))
         }
@@ -933,7 +933,7 @@ pub fn early_warn(output: config::ErrorOutputType, msg: &str) {
         config::ErrorOutputType::HumanReadable(color_config) => {
             Box::new(EmitterWriter::stderr(color_config, None, false))
         }
-        config::ErrorOutputType::Json => Box::new(JsonEmitter::basic()),
+        config::ErrorOutputType::Json(pretty) => Box::new(JsonEmitter::basic(pretty)),
         config::ErrorOutputType::Short(color_config) => {
             Box::new(EmitterWriter::stderr(color_config, None, true))
         }

src/libsyntax/json.rs

@@ -30,36 +30,41 @@ use std::rc::Rc;
 use std::io::{self, Write};
 use std::vec;
 
-use rustc_serialize::json::as_json;
+use rustc_serialize::json::{as_json, as_pretty_json};
 
 pub struct JsonEmitter {
     dst: Box<Write + Send>,
     registry: Option<Registry>,
     cm: Rc<CodeMapper + 'static>,
+    pretty: bool,
 }
 
 impl JsonEmitter {
     pub fn stderr(registry: Option<Registry>,
-                  code_map: Rc<CodeMap>) -> JsonEmitter {
+                  code_map: Rc<CodeMap>,
+                  pretty: bool) -> JsonEmitter {
         JsonEmitter {
             dst: Box::new(io::stderr()),
             registry,
             cm: code_map,
+            pretty,
         }
     }
 
-    pub fn basic() -> JsonEmitter {
+    pub fn basic(pretty: bool) -> JsonEmitter {
         let file_path_mapping = FilePathMapping::empty();
-        JsonEmitter::stderr(None, Rc::new(CodeMap::new(file_path_mapping)))
+        JsonEmitter::stderr(None, Rc::new(CodeMap::new(file_path_mapping)), pretty)
     }
 
     pub fn new(dst: Box<Write + Send>,
                registry: Option<Registry>,
-               code_map: Rc<CodeMap>) -> JsonEmitter {
+               code_map: Rc<CodeMap>,
+               pretty: bool) -> JsonEmitter {
         JsonEmitter {
             dst,
             registry,
             cm: code_map,
+            pretty,
         }
     }
 }
@@ -67,7 +72,12 @@ impl JsonEmitter {
 impl Emitter for JsonEmitter {
     fn emit(&mut self, db: &DiagnosticBuilder) {
         let data = Diagnostic::from_diagnostic_builder(db, self);
-        if let Err(e) = writeln!(&mut self.dst, "{}", as_json(&data)) {
+        let result = if self.pretty {
+            writeln!(&mut self.dst, "{}", as_pretty_json(&data))
+        } else {
+            writeln!(&mut self.dst, "{}", as_json(&data))
+        };
+        if let Err(e) = result {
             panic!("failed to print diagnostics: {:?}", e);
         }
     }

src/test/ui/lint/unused_parens_json_suggestion.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: --error-format json
+// compile-flags: --error-format pretty-json -Zpretty_json_error_format
 
 // The output for humans should just highlight the whole span without showing
 // the suggested replacement, but we also want to test that suggested

src/test/ui/lint/unused_parens_json_suggestion.stderr

@@ -1 +1,91 @@
-{"message":"unnecessary parentheses around assigned value","code":{"code":"unused_parens","explanation":null},"level":"warning","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":1001,"byte_end":1014,"line_start":24,"line_end":24,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[{"message":"lint level defined here","code":null,"level":"note","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":847,"byte_end":860,"line_start":19,"line_end":19,"column_start":9,"column_end":22,"is_primary":true,"text":[{"text":"#![warn(unused_parens)]","highlight_start":9,"highlight_end":22}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[],"rendered":null},{"message":"remove these parentheses","code":null,"level":"help","spans":[{"file_name":"$DIR/unused_parens_json_suggestion.rs","byte_start":1001,"byte_end":1014,"line_start":24,"line_end":24,"column_start":14,"column_end":27,"is_primary":true,"text":[{"text":"    let _a = (1 / (2 + 3));","highlight_start":14,"highlight_end":27}],"label":null,"suggested_replacement":"1 / (2 + 3)","expansion":null}],"children":[],"rendered":null}],"rendered":null}
+{
+  "message": "unnecessary parentheses around assigned value",
+  "code": {
+    "code": "unused_parens",
+    "explanation": null
+  },
+  "level": "warning",
+  "spans": [
+    {
+      "file_name": "$DIR/unused_parens_json_suggestion.rs",
+      "byte_start": 1035,
+      "byte_end": 1048,
+      "line_start": 24,
+      "line_end": 24,
+      "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": "lint level defined here",
+      "code": null,
+      "level": "note",
+      "spans": [
+        {
+          "file_name": "$DIR/unused_parens_json_suggestion.rs",
+          "byte_start": 881,
+          "byte_end": 894,
+          "line_start": 19,
+          "line_end": 19,
+          "column_start": 9,
+          "column_end": 22,
+          "is_primary": true,
+          "text": [
+            {
+              "text": "#![warn(unused_parens)]",
+              "highlight_start": 9,
+              "highlight_end": 22
+            }
+          ],
+          "label": null,
+          "suggested_replacement": null,
+          "expansion": null
+        }
+      ],
+      "children": [],
+      "rendered": null
+    },
+    {
+      "message": "remove these parentheses",
+      "code": null,
+      "level": "help",
+      "spans": [
+        {
+          "file_name": "$DIR/unused_parens_json_suggestion.rs",
+          "byte_start": 1035,
+          "byte_end": 1048,
+          "line_start": 24,
+          "line_end": 24,
+          "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
+}

src/test/ui/lint/use_suggestion_json.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// compile-flags: --error-format json
+// compile-flags: --error-format pretty-json -Zpretty_json_error_format
 
 // The output for humans should just highlight the whole span without showing
 // the suggested replacement, but we also want to test that suggested

src/tools/compiletest/src/runtest.rs

@@ -2378,7 +2378,8 @@ actual:\n\
     fn normalize_output(&self, output: &str, custom_rules: &[(String, String)]) -> String {
         let parent_dir = self.testpaths.file.parent().unwrap();
         let cflags = self.props.compile_flags.join(" ");
-        let parent_dir_str = if cflags.contains("--error-format json") {
+        let parent_dir_str = if cflags.contains("--error-format json")
+                             || cflags.contains("--error-format pretty-json") {
             parent_dir.display().to_string().replace("\\", "\\\\")
         } else {
             parent_dir.display().to_string()