1 //! Validates syntax inside Rust code blocks (\`\`\`rust).
2 use rustc_data_structures::sync::{Lock, Lrc};
3 use rustc_errors::{emitter::Emitter, Applicability, Diagnostic, Handler};
4 use rustc_middle::lint::LintDiagnosticBuilder;
5 use rustc_parse::parse_stream_from_source_str;
6 use rustc_session::parse::ParseSess;
7 use rustc_span::hygiene::{AstPass, ExpnData, ExpnKind, LocalExpnId};
8 use rustc_span::source_map::{FilePathMapping, SourceMap};
9 use rustc_span::{FileName, InnerSpan, DUMMY_SP};
12 use crate::core::DocContext;
13 use crate::html::markdown::{self, RustCodeBlock};
14 use crate::passes::Pass;
15 use crate::visit::DocVisitor;
17 crate const CHECK_CODE_BLOCK_SYNTAX: Pass = Pass {
18 name: "check-code-block-syntax",
19 run: check_code_block_syntax,
20 description: "validates syntax inside Rust code blocks",
23 crate fn check_code_block_syntax(krate: clean::Crate, cx: &mut DocContext<'_>) -> clean::Crate {
24 SyntaxChecker { cx }.visit_crate(&krate);
28 struct SyntaxChecker<'a, 'tcx> {
29 cx: &'a DocContext<'tcx>,
32 impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
33 fn check_rust_syntax(&self, item: &clean::Item, dox: &str, code_block: RustCodeBlock) {
34 let buffer = Lrc::new(Lock::new(Buffer::default()));
35 let emitter = BufferEmitter { buffer: Lrc::clone(&buffer) };
37 let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
38 let handler = Handler::with_emitter(false, None, Box::new(emitter));
39 let source = dox[code_block.code].to_owned();
40 let sess = ParseSess::with_span_handler(handler, sm);
42 let edition = code_block.lang_string.edition.unwrap_or_else(|| self.cx.tcx.sess.edition());
43 let expn_data = ExpnData::default(
44 ExpnKind::AstPass(AstPass::TestHarness),
50 let expn_id = LocalExpnId::fresh(expn_data, self.cx.tcx.create_stable_hashing_context());
51 let span = DUMMY_SP.fresh_expansion(expn_id);
53 let is_empty = rustc_driver::catch_fatal_errors(|| {
54 parse_stream_from_source_str(
55 FileName::Custom(String::from("doctest")),
63 let buffer = buffer.borrow();
65 if !buffer.has_errors && !is_empty {
66 // No errors in a non-empty program.
70 let Some(local_id) = item.def_id.as_def_id().and_then(|x| x.as_local())
72 // We don't need to check the syntax for other crates so returning
73 // without doing anything should not be a problem.
77 let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_id);
78 let empty_block = code_block.lang_string == Default::default() && code_block.is_fenced;
79 let is_ignore = code_block.lang_string.ignore != markdown::Ignore::None;
81 // The span and whether it is precise or not.
82 let (sp, precise_span) = match super::source_span_for_markdown_range(
88 Some(sp) => (sp, true),
89 None => (item.attr_span(self.cx.tcx), false),
92 // lambda that will use the lint to start a new diagnostic and add
93 // a suggestion to it when needed.
94 let diag_builder = |lint: LintDiagnosticBuilder<'_, ()>| {
95 let explanation = if is_ignore {
96 "`ignore` code blocks require valid Rust code for syntax highlighting; \
97 mark blocks that do not contain Rust code as text"
99 "mark blocks that do not contain Rust code as text"
101 let msg = if buffer.has_errors {
102 "could not parse code block as Rust code"
104 "Rust code block is empty"
106 let mut diag = lint.build(msg);
110 // giving an accurate suggestion is hard because `ignore` might not have come first in the list.
111 // just give a `help` instead.
113 sp.from_inner(InnerSpan::new(0, 3)),
114 &format!("{}: ```text", explanation),
116 } else if empty_block {
117 diag.span_suggestion(
118 sp.from_inner(InnerSpan::new(0, 3)).shrink_to_hi(),
120 String::from("text"),
121 Applicability::MachineApplicable,
124 } else if empty_block || is_ignore {
125 diag.help(&format!("{}: ```text", explanation));
128 // FIXME(#67563): Provide more context for these errors by displaying the spans inline.
129 for message in buffer.messages.iter() {
136 // Finally build and emit the completed diagnostic.
137 // All points of divergence have been handled earlier so this can be
138 // done the same way whether the span is precise or not.
139 self.cx.tcx.struct_span_lint_hir(
140 crate::lint::INVALID_RUST_CODEBLOCKS,
148 impl<'a, 'tcx> DocVisitor for SyntaxChecker<'a, 'tcx> {
149 fn visit_item(&mut self, item: &clean::Item) {
150 if let Some(dox) = &item.attrs.collapsed_doc_value() {
151 let sp = item.attr_span(self.cx.tcx);
152 let extra = crate::html::markdown::ExtraInfo::new_did(
154 item.def_id.expect_def_id(),
157 for code_block in markdown::rust_code_blocks(dox, &extra) {
158 self.check_rust_syntax(&item, dox, code_block);
162 self.visit_item_recur(item)
168 messages: Vec<String>,
172 struct BufferEmitter {
173 buffer: Lrc<Lock<Buffer>>,
176 impl Emitter for BufferEmitter {
177 fn emit_diagnostic(&mut self, diag: &Diagnostic) {
178 let mut buffer = self.buffer.borrow_mut();
179 buffer.messages.push(format!("error from rustc: {}", diag.message[0].0));
181 buffer.has_errors = true;
185 fn source_map(&self) -> Option<&Lrc<SourceMap>> {