1 //! Validates syntax inside Rust code blocks (\`\`\`rust).
2 use rustc_data_structures::sync::{Lock, Lrc};
4 emitter::Emitter, Applicability, Diagnostic, Handler, LazyFallbackBundle, LintDiagnosticBuilder,
6 use rustc_parse::parse_stream_from_source_str;
7 use rustc_session::parse::ParseSess;
8 use rustc_span::hygiene::{AstPass, ExpnData, ExpnKind, LocalExpnId};
9 use rustc_span::source_map::{FilePathMapping, SourceMap};
10 use rustc_span::{FileName, InnerSpan, DUMMY_SP};
13 use crate::core::DocContext;
14 use crate::html::markdown::{self, RustCodeBlock};
15 use crate::passes::Pass;
16 use crate::visit::DocVisitor;
18 pub(crate) const CHECK_CODE_BLOCK_SYNTAX: Pass = Pass {
19 name: "check-code-block-syntax",
20 run: check_code_block_syntax,
21 description: "validates syntax inside Rust code blocks",
24 pub(crate) fn check_code_block_syntax(
26 cx: &mut DocContext<'_>,
28 SyntaxChecker { cx }.visit_crate(&krate);
32 struct SyntaxChecker<'a, 'tcx> {
33 cx: &'a DocContext<'tcx>,
36 impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
37 fn check_rust_syntax(&self, item: &clean::Item, dox: &str, code_block: RustCodeBlock) {
38 let buffer = Lrc::new(Lock::new(Buffer::default()));
40 rustc_errors::fallback_fluent_bundle(rustc_errors::DEFAULT_LOCALE_RESOURCES, false);
41 let emitter = BufferEmitter { buffer: Lrc::clone(&buffer), fallback_bundle };
43 let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
44 let handler = Handler::with_emitter(false, None, Box::new(emitter));
45 let source = dox[code_block.code].to_owned();
46 let sess = ParseSess::with_span_handler(handler, sm);
48 let edition = code_block.lang_string.edition.unwrap_or_else(|| self.cx.tcx.sess.edition());
49 let expn_data = ExpnData::default(
50 ExpnKind::AstPass(AstPass::TestHarness),
57 self.cx.tcx.with_stable_hashing_context(|hcx| LocalExpnId::fresh(expn_data, hcx));
58 let span = DUMMY_SP.fresh_expansion(expn_id);
60 let is_empty = rustc_driver::catch_fatal_errors(|| {
61 parse_stream_from_source_str(
62 FileName::Custom(String::from("doctest")),
70 let buffer = buffer.borrow();
72 if !buffer.has_errors && !is_empty {
73 // No errors in a non-empty program.
77 let Some(local_id) = item.item_id.as_def_id().and_then(|x| x.as_local())
79 // We don't need to check the syntax for other crates so returning
80 // without doing anything should not be a problem.
84 let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_id);
85 let empty_block = code_block.lang_string == Default::default() && code_block.is_fenced;
86 let is_ignore = code_block.lang_string.ignore != markdown::Ignore::None;
88 // The span and whether it is precise or not.
89 let (sp, precise_span) = match super::source_span_for_markdown_range(
95 Some(sp) => (sp, true),
96 None => (item.attr_span(self.cx.tcx), false),
99 // lambda that will use the lint to start a new diagnostic and add
100 // a suggestion to it when needed.
101 let diag_builder = |lint: LintDiagnosticBuilder<'_, ()>| {
102 let explanation = if is_ignore {
103 "`ignore` code blocks require valid Rust code for syntax highlighting; \
104 mark blocks that do not contain Rust code as text"
106 "mark blocks that do not contain Rust code as text"
108 let msg = if buffer.has_errors {
109 "could not parse code block as Rust code"
111 "Rust code block is empty"
113 let mut diag = lint.build(msg);
117 // giving an accurate suggestion is hard because `ignore` might not have come first in the list.
118 // just give a `help` instead.
120 sp.from_inner(InnerSpan::new(0, 3)),
121 &format!("{}: ```text", explanation),
123 } else if empty_block {
124 diag.span_suggestion(
125 sp.from_inner(InnerSpan::new(0, 3)).shrink_to_hi(),
128 Applicability::MachineApplicable,
131 } else if empty_block || is_ignore {
132 diag.help(&format!("{}: ```text", explanation));
135 // FIXME(#67563): Provide more context for these errors by displaying the spans inline.
136 for message in buffer.messages.iter() {
143 // Finally build and emit the completed diagnostic.
144 // All points of divergence have been handled earlier so this can be
145 // done the same way whether the span is precise or not.
146 self.cx.tcx.struct_span_lint_hir(
147 crate::lint::INVALID_RUST_CODEBLOCKS,
155 impl<'a, 'tcx> DocVisitor for SyntaxChecker<'a, 'tcx> {
156 fn visit_item(&mut self, item: &clean::Item) {
157 if let Some(dox) = &item.attrs.collapsed_doc_value() {
158 let sp = item.attr_span(self.cx.tcx);
159 let extra = crate::html::markdown::ExtraInfo::new_did(
161 item.item_id.expect_def_id(),
164 for code_block in markdown::rust_code_blocks(dox, &extra) {
165 self.check_rust_syntax(item, dox, code_block);
169 self.visit_item_recur(item)
175 messages: Vec<String>,
179 struct BufferEmitter {
180 buffer: Lrc<Lock<Buffer>>,
181 fallback_bundle: LazyFallbackBundle,
184 impl Emitter for BufferEmitter {
185 fn emit_diagnostic(&mut self, diag: &Diagnostic) {
186 let mut buffer = self.buffer.borrow_mut();
187 // FIXME(davidtwco): need to support translation here eventually
188 buffer.messages.push(format!("error from rustc: {}", diag.message[0].0.expect_str()));
190 buffer.has_errors = true;
194 fn source_map(&self) -> Option<&Lrc<SourceMap>> {
198 fn fluent_bundle(&self) -> Option<&Lrc<rustc_errors::FluentBundle>> {
202 fn fallback_fluent_bundle(&self) -> &rustc_errors::FluentBundle {
203 &**self.fallback_bundle