src/librustdoc/passes/check_code_block_syntax.rs

   1 use rustc_data_structures::sync::{Lock, Lrc};
   2 use rustc_errors::{emitter::Emitter, Applicability, Diagnostic, Handler};
   3 use rustc_middle::lint::LintDiagnosticBuilder;
   4 use rustc_parse::parse_stream_from_source_str;
   5 use rustc_session::parse::ParseSess;
   6 use rustc_span::source_map::{FilePathMapping, SourceMap};
   7 use rustc_span::{hygiene::AstPass, ExpnData, ExpnKind, FileName, InnerSpan, DUMMY_SP};
   8
   9 use crate::clean;
  10 use crate::core::DocContext;
  11 use crate::fold::DocFolder;
  12 use crate::html::markdown::{self, RustCodeBlock};
  13 use crate::passes::Pass;
  14
  15 crate const CHECK_CODE_BLOCK_SYNTAX: Pass = Pass {
  16     name: "check-code-block-syntax",
  17     run: check_code_block_syntax,
  18     description: "validates syntax inside Rust code blocks",
  19 };
  20
  21 crate fn check_code_block_syntax(krate: clean::Crate, cx: &mut DocContext<'_>) -> clean::Crate {
  22     SyntaxChecker { cx }.fold_crate(krate)
  23 }
  24
  25 struct SyntaxChecker<'a, 'tcx> {
  26     cx: &'a DocContext<'tcx>,
  27 }
  28
  29 impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
  30     fn check_rust_syntax(&self, item: &clean::Item, dox: &str, code_block: RustCodeBlock) {
  31         let buffer = Lrc::new(Lock::new(Buffer::default()));
  32         let emitter = BufferEmitter { buffer: Lrc::clone(&buffer) };
  33
  34         let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
  35         let handler = Handler::with_emitter(false, None, Box::new(emitter));
  36         let source = dox[code_block.code].to_owned();
  37         let sess = ParseSess::with_span_handler(handler, sm);
  38
  39         let edition = code_block.lang_string.edition.unwrap_or(self.cx.tcx.sess.edition());
  40         let expn_data = ExpnData::default(
  41             ExpnKind::AstPass(AstPass::TestHarness),
  42             DUMMY_SP,
  43             edition,
  44             None,
  45             None,
  46         );
  47         let span = DUMMY_SP.fresh_expansion(expn_data, self.cx.tcx.create_stable_hashing_context());
  48
  49         let is_empty = rustc_driver::catch_fatal_errors(|| {
  50             parse_stream_from_source_str(
  51                 FileName::Custom(String::from("doctest")),
  52                 source,
  53                 &sess,
  54                 Some(span),
  55             )
  56             .is_empty()
  57         })
  58         .unwrap_or(false);
  59         let buffer = buffer.borrow();
  60
  61         if !buffer.has_errors && !is_empty {
  62             // No errors in a non-empty program.
  63             return;
  64         }
  65
  66         let local_id = match item.def_id.as_def_id().and_then(|x| x.as_local()) {
  67             Some(id) => id,
  68             // We don't need to check the syntax for other crates so returning
  69             // without doing anything should not be a problem.
  70             None => return,
  71         };
  72
  73         let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_id);
  74         let empty_block = code_block.lang_string == Default::default() && code_block.is_fenced;
  75         let is_ignore = code_block.lang_string.ignore != markdown::Ignore::None;
  76
  77         // The span and whether it is precise or not.
  78         let (sp, precise_span) = match super::source_span_for_markdown_range(
  79             self.cx.tcx,
  80             &dox,
  81             &code_block.range,
  82             &item.attrs,
  83         ) {
  84             Some(sp) => (sp, true),
  85             None => (item.attr_span(self.cx.tcx), false),
  86         };
  87
  88         // lambda that will use the lint to start a new diagnostic and add
  89         // a suggestion to it when needed.
  90         let diag_builder = |lint: LintDiagnosticBuilder<'_>| {
  91             let explanation = if is_ignore {
  92                 "`ignore` code blocks require valid Rust code for syntax highlighting; \
  93                     mark blocks that do not contain Rust code as text"
  94             } else {
  95                 "mark blocks that do not contain Rust code as text"
  96             };
  97             let msg = if buffer.has_errors {
  98                 "could not parse code block as Rust code"
  99             } else {
 100                 "Rust code block is empty"
 101             };
 102             let mut diag = lint.build(msg);
 103
 104             if precise_span {
 105                 if is_ignore {
 106                     // giving an accurate suggestion is hard because `ignore` might not have come first in the list.
 107                     // just give a `help` instead.
 108                     diag.span_help(
 109                         sp.from_inner(InnerSpan::new(0, 3)),
 110                         &format!("{}: ```text", explanation),
 111                     );
 112                 } else if empty_block {
 113                     diag.span_suggestion(
 114                         sp.from_inner(InnerSpan::new(0, 3)),
 115                         explanation,
 116                         String::from("```text"),
 117                         Applicability::MachineApplicable,
 118                     );
 119                 }
 120             } else if empty_block || is_ignore {
 121                 diag.help(&format!("{}: ```text", explanation));
 122             }
 123
 124             // FIXME(#67563): Provide more context for these errors by displaying the spans inline.
 125             for message in buffer.messages.iter() {
 126                 diag.note(&message);
 127             }
 128
 129             diag.emit();
 130         };
 131
 132         // Finally build and emit the completed diagnostic.
 133         // All points of divergence have been handled earlier so this can be
 134         // done the same way whether the span is precise or not.
 135         self.cx.tcx.struct_span_lint_hir(
 136             crate::lint::INVALID_RUST_CODEBLOCKS,
 137             hir_id,
 138             sp,
 139             diag_builder,
 140         );
 141     }
 142 }
 143
 144 impl<'a, 'tcx> DocFolder for SyntaxChecker<'a, 'tcx> {
 145     fn fold_item(&mut self, item: clean::Item) -> Option<clean::Item> {
 146         if let Some(dox) = &item.attrs.collapsed_doc_value() {
 147             let sp = item.attr_span(self.cx.tcx);
 148             let extra = crate::html::markdown::ExtraInfo::new_did(
 149                 self.cx.tcx,
 150                 item.def_id.expect_def_id(),
 151                 sp,
 152             );
 153             for code_block in markdown::rust_code_blocks(&dox, &extra) {
 154                 self.check_rust_syntax(&item, &dox, code_block);
 155             }
 156         }
 157
 158         Some(self.fold_item_recur(item))
 159     }
 160 }
 161
 162 #[derive(Default)]
 163 struct Buffer {
 164     messages: Vec<String>,
 165     has_errors: bool,
 166 }
 167
 168 struct BufferEmitter {
 169     buffer: Lrc<Lock<Buffer>>,
 170 }
 171
 172 impl Emitter for BufferEmitter {
 173     fn emit_diagnostic(&mut self, diag: &Diagnostic) {
 174         let mut buffer = self.buffer.borrow_mut();
 175         buffer.messages.push(format!("error from rustc: {}", diag.message[0].0));
 176         if diag.is_error() {
 177             buffer.has_errors = true;
 178         }
 179     }
 180
 181     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
 182         None
 183     }
 184 }