1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! A JSON emitter for errors.
13 //! This works by converting errors to a simplified structural format (see the
14 //! structs at the start of the file) and then serializing them. These should
15 //! contain as much information about the error as possible.
17 //! The format of the JSON output should be considered *unstable*. For now the
18 //! structs at the end of this file (Diagnostic*) specify the error format.
20 // FIXME spec the JSON output properly.
22 use codemap::{CodeMap, FilePathMapping};
23 use syntax_pos::{self, MacroBacktrace, Span, SpanLabel, MultiSpan};
24 use errors::registry::Registry;
25 use errors::{DiagnosticBuilder, SubDiagnostic, RenderSpan, CodeSuggestion, CodeMapper};
26 use errors::emitter::Emitter;
29 use std::io::{self, Write};
32 use rustc_serialize::json::as_json;
34 pub struct JsonEmitter {
35 dst: Box<Write + Send>,
36 registry: Option<Registry>,
37 cm: Rc<CodeMapper + 'static>,
41 pub fn stderr(registry: Option<Registry>,
42 code_map: Rc<CodeMap>) -> JsonEmitter {
44 dst: Box::new(io::stderr()),
50 pub fn basic() -> JsonEmitter {
51 let file_path_mapping = FilePathMapping::empty();
52 JsonEmitter::stderr(None, Rc::new(CodeMap::new(file_path_mapping)))
55 pub fn new(dst: Box<Write + Send>,
56 registry: Option<Registry>,
57 code_map: Rc<CodeMap>) -> JsonEmitter {
66 impl Emitter for JsonEmitter {
67 fn emit(&mut self, db: &DiagnosticBuilder) {
68 let data = Diagnostic::from_diagnostic_builder(db, self);
69 if let Err(e) = writeln!(&mut self.dst, "{}", as_json(&data)) {
70 panic!("failed to print diagnostics: {:?}", e);
75 // The following data types are provided just for serialisation.
77 #[derive(RustcEncodable)]
79 /// The primary error message.
81 code: Option<DiagnosticCode>,
82 /// "error: internal compiler error", "error", "warning", "note", "help".
84 spans: Vec<DiagnosticSpan>,
85 /// Associated diagnostic messages.
86 children: Vec<Diagnostic>,
87 /// The message as rustc would render it. Currently this is only
88 /// `Some` for "suggestions", but eventually it will include all
90 rendered: Option<String>,
93 #[derive(RustcEncodable)]
94 struct DiagnosticSpan {
101 /// 1-based, character offset.
104 /// Is this a "primary" span -- meaning the point, or one of the points,
105 /// where the error occurred?
107 /// Source text from the start of line_start to the end of line_end.
108 text: Vec<DiagnosticSpanLine>,
109 /// Label that should be placed at this location (if any)
110 label: Option<String>,
111 /// If we are suggesting a replacement, this will contain text
112 /// that should be sliced in atop this span. You may prefer to
113 /// load the fully rendered version from the parent `Diagnostic`,
115 suggested_replacement: Option<String>,
116 /// Macro invocations that created the code at this span, if any.
117 expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
120 #[derive(RustcEncodable)]
121 struct DiagnosticSpanLine {
124 /// 1-based, character offset in self.text.
125 highlight_start: usize,
127 highlight_end: usize,
130 #[derive(RustcEncodable)]
131 struct DiagnosticSpanMacroExpansion {
132 /// span where macro was applied to generate this code; note that
133 /// this may itself derive from a macro (if
134 /// `span.expansion.is_some()`)
135 span: DiagnosticSpan,
137 /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
138 macro_decl_name: String,
140 /// span where macro was defined (if known)
141 def_site_span: Option<DiagnosticSpan>,
144 #[derive(RustcEncodable)]
145 struct DiagnosticCode {
148 /// An explanation for the code.
149 explanation: Option<&'static str>,
153 fn from_diagnostic_builder(db: &DiagnosticBuilder,
156 let sugg = db.suggestions.iter().flat_map(|sugg| {
157 je.render(sugg).into_iter().map(move |rendered| {
159 message: sugg.msg.clone(),
162 spans: DiagnosticSpan::from_suggestion(sugg, je),
164 rendered: Some(rendered),
169 message: db.message(),
170 code: DiagnosticCode::map_opt_string(db.code.clone(), je),
171 level: db.level.to_str(),
172 spans: DiagnosticSpan::from_multispan(&db.span, je),
173 children: db.children.iter().map(|c| {
174 Diagnostic::from_sub_diagnostic(c, je)
175 }).chain(sugg).collect(),
180 fn from_sub_diagnostic(db: &SubDiagnostic, je: &JsonEmitter) -> Diagnostic {
182 message: db.message(),
184 level: db.level.to_str(),
185 spans: db.render_span.as_ref()
186 .map(|sp| DiagnosticSpan::from_render_span(sp, je))
187 .unwrap_or_else(|| DiagnosticSpan::from_multispan(&db.span, je)),
194 impl DiagnosticSpan {
195 fn from_span_label(span: SpanLabel,
196 suggestion: Option<&String>,
199 Self::from_span_etc(span.span,
206 fn from_span_etc(span: Span,
208 label: Option<String>,
209 suggestion: Option<&String>,
212 // obtain the full backtrace from the `macro_backtrace`
213 // helper; in some ways, it'd be better to expand the
214 // backtrace ourselves, but the `macro_backtrace` helper makes
215 // some decision, such as dropping some frames, and I don't
216 // want to duplicate that logic here.
217 let backtrace = span.macro_backtrace().into_iter();
218 DiagnosticSpan::from_span_full(span,
226 fn from_span_full(span: Span,
228 label: Option<String>,
229 suggestion: Option<&String>,
230 mut backtrace: vec::IntoIter<MacroBacktrace>,
233 let start = je.cm.lookup_char_pos(span.lo);
234 let end = je.cm.lookup_char_pos(span.hi);
235 let backtrace_step = backtrace.next().map(|bt| {
237 Self::from_span_full(bt.call_site,
243 let def_site_span = bt.def_site_span.map(|sp| {
244 Self::from_span_full(sp,
251 Box::new(DiagnosticSpanMacroExpansion {
253 macro_decl_name: bt.macro_decl_name,
258 file_name: start.file.name.clone(),
259 byte_start: span.lo.0 - start.file.start_pos.0,
260 byte_end: span.hi.0 - start.file.start_pos.0,
261 line_start: start.line,
263 column_start: start.col.0 + 1,
264 column_end: end.col.0 + 1,
266 text: DiagnosticSpanLine::from_span(span, je),
267 suggested_replacement: suggestion.cloned(),
268 expansion: backtrace_step,
273 fn from_multispan(msp: &MultiSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
276 .map(|span_str| Self::from_span_label(span_str, None, je))
280 fn from_suggestion(suggestion: &CodeSuggestion, je: &JsonEmitter)
281 -> Vec<DiagnosticSpan> {
282 suggestion.substitution_parts
284 .flat_map(|substitution| {
285 substitution.substitutions.iter().map(move |suggestion| {
286 let span_label = SpanLabel {
287 span: substitution.span,
291 DiagnosticSpan::from_span_label(span_label,
299 fn from_render_span(rsp: &RenderSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
301 RenderSpan::FullSpan(ref msp) =>
302 DiagnosticSpan::from_multispan(msp, je),
303 // regular diagnostics don't produce this anymore
304 // FIXME(oli_obk): remove it entirely
305 RenderSpan::Suggestion(_) => unreachable!(),
310 impl DiagnosticSpanLine {
311 fn line_from_filemap(fm: &syntax_pos::FileMap,
315 -> DiagnosticSpanLine {
317 text: fm.get_line(index).map_or(String::new(), |l| l.into_owned()),
318 highlight_start: h_start,
319 highlight_end: h_end,
323 /// Create a list of DiagnosticSpanLines from span - each line with any part
324 /// of `span` gets a DiagnosticSpanLine, with the highlight indicating the
325 /// `span` within the line.
326 fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
327 je.cm.span_to_lines(span)
329 let fm = &*lines.file;
333 DiagnosticSpanLine::line_from_filemap(fm,
335 line.start_col.0 + 1,
340 .unwrap_or_else(|_| vec![])
344 impl DiagnosticCode {
345 fn map_opt_string(s: Option<String>, je: &JsonEmitter) -> Option<DiagnosticCode> {
348 let explanation = je.registry
350 .and_then(|registry| registry.find_description(&s));
361 fn render(&self, suggestion: &CodeSuggestion) -> Vec<String> {
362 suggestion.splice_lines(&*self.cm).iter().map(|line| line.0.to_owned()).collect()