rustdoc: Properly detect syntactically invalid doctests (to fix a regression)

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -232,7 +232,7 @@ pub(crate) enum AttributeOrder {
  ///
  /// Attributes are processed from bottom to top, so this raises a warning/error on all the attributes
  /// further above the lowest one:
- /// ```
+ /// ```ignore (illustrative)
  /// #[stable(since="1.0")] //~ WARNING duplicated attribute
  /// #[stable(since="2.0")]
  /// ```
@@ -243,7 +243,7 @@ pub(crate) enum AttributeOrder {
  ///
  /// Attributes are processed from bottom to top, so this raises a warning/error on all the attributes
  /// below the highest one:
- /// ```
+ /// ```ignore (illustrative)
  /// #[path="foo.rs"]
  /// #[path="bar.rs"] //~ WARNING duplicated attribute
  /// ```

compiler/rustc_errors/src/emitter.rs

@@ -205,11 +205,6 @@ pub trait Emitter {
  true
  }
 
- /// Checks if we can use colors in the current output stream.
- fn supports_color(&self) -> bool {
- false
- }
-
  fn source_map(&self) -> Option<&SourceMap>;
 
  fn translator(&self) -> &Translator;

src/librustdoc/doctest/make.rs

@@ -2,19 +2,18 @@
 //! runnable, e.g. by adding a `main` function if it doesn't already exist.
 
 use std::fmt::{self, Write as _};
-use std::io;
 use std::sync::Arc;
 
 use rustc_ast::token::{Delimiter, TokenKind};
 use rustc_ast::tokenstream::TokenTree;
 use rustc_ast::{self as ast, AttrStyle, HasAttrs, StmtKind};
-use rustc_errors::emitter::stderr_destination;
-use rustc_errors::{AutoStream, ColorConfig, DiagCtxtHandle};
+use rustc_errors::emitter::SilentEmitter;
+use rustc_errors::{DiagCtxt, DiagCtxtHandle};
 use rustc_parse::lexer::StripTokens;
 use rustc_parse::new_parser_from_source_str;
 use rustc_session::parse::ParseSess;
 use rustc_span::edition::{DEFAULT_EDITION, Edition};
-use rustc_span::source_map::SourceMap;
+use rustc_span::source_map::{FilePathMapping, SourceMap};
 use rustc_span::symbol::sym;
 use rustc_span::{DUMMY_SP, FileName, Span, kw};
 use tracing::debug;
@@ -445,40 +444,33 @@ fn parse_source(
  parent_dcx: Option<DiagCtxtHandle<'_>>,
  span: Span,
 ) -> Result<ParseSourceInfo, ()> {
- use rustc_errors::DiagCtxt;
- use rustc_errors::emitter::{Emitter, HumanEmitter};
- use rustc_span::source_map::FilePathMapping;
-
  let mut info =
  ParseSourceInfo { already_has_extern_crate: crate_name.is_none(), ..Default::default() };
 
  let wrapped_source = format!("{DOCTEST_CODE_WRAPPER}{source}\n}}");
 
- let filename = FileName::anon_source_code(&wrapped_source);
-
- let sm = Arc::new(SourceMap::new(FilePathMapping::empty()));
- let translator = rustc_driver::default_translator();
- info.supports_color =
- HumanEmitter::new(stderr_destination(ColorConfig::Auto), translator.clone())
- .supports_color();
- // Any errors in parsing should also appear when the doctest is compiled for real, so just
- // send all the errors that the parser emits directly into a `Sink` instead of stderr.
- let emitter = HumanEmitter::new(AutoStream::never(Box::new(io::sink())), translator);
+ // Any parse errors should also appear when the doctest is compiled for real,
+ // so just suppress them here.
+ let emitter = SilentEmitter { translator: rustc_driver::default_translator() };
 
  // FIXME(misdreavus): pass `-Z treat-err-as-bug` to the doctest parser
  let dcx = DiagCtxt::new(Box::new(emitter)).disable_warnings();
- let psess = ParseSess::with_dcx(dcx, sm);
+ let psess = ParseSess::with_dcx(dcx, Arc::new(SourceMap::new(FilePathMapping::empty())));
 
  // Don't strip any tokens; it wouldn't matter anyway because the source is wrapped in a function.
- let mut parser =
- match new_parser_from_source_str(&psess, filename, wrapped_source, StripTokens::Nothing) {
- Ok(p) => p,
- Err(errs) => {
- errs.into_iter().for_each(|err| err.cancel());
- reset_error_count(&psess);
- return Err(());
- }
- };
+ let mut parser = match new_parser_from_source_str(
+ &psess,
+ FileName::anon_source_code(&wrapped_source),
+ wrapped_source,
+ StripTokens::Nothing,
+ ) {
+ Ok(p) => p,
+ Err(errs) => {
+ errs.into_iter().for_each(|err| err.cancel());
+ reset_error_count(&psess);
+ return Err(());
+ }
+ };
 
  fn push_to_s(s: &mut String, source: &str, span: rustc_span::Span, prev_span_hi: &mut usize) {
  let extra_len = DOCTEST_CODE_WRAPPER.len();
@@ -531,7 +523,12 @@ fn parse_source(
  let result = match parsed {
  Ok(Some(ref item))
  if let ast::ItemKind::Fn(ref fn_item) = item.kind
- && let Some(ref body) = fn_item.body =>
+ && let Some(ref body) = fn_item.body
+ // The parser might've recovered from some syntax errors and thus returned `Ok(_)`.
+ // However, since we've suppressed diagnostic emission above, we must ensure that
+ // we mark the doctest as syntactically invalid. Otherwise, we can end up generating
+ // a runnable doctest that's free of any errors even though the source was malformed.
+ && psess.dcx().has_errors().is_none() =>
  {
  for attr in &item.attrs {
  if attr.style == AttrStyle::Outer || attr.has_any_name(not_crate_attrs) {
@@ -587,14 +584,9 @@ fn parse_source(
  }
  }
  }
- StmtKind::Expr(ref expr) => {
- if matches!(expr.kind, ast::ExprKind::Err(_)) {
- reset_error_count(&psess);
- return Err(());
- }
- has_non_items = true;
+ StmtKind::Let(_) | StmtKind::Expr(_) | StmtKind::Semi(_) | StmtKind::Empty => {
+ has_non_items = true
  }
- StmtKind::Let(_) | StmtKind::Semi(_) | StmtKind::Empty => has_non_items = true,
  }
 
  // Weirdly enough, the `Stmt` span doesn't include its attributes, so we need to

tests/rustdoc-ui/doctest/doctest-output-include-fail.stdout

@@ -13,7 +13,15 @@ LL | let x = 234 // no semicolon here! oh no!
 LL | }
  | - unexpected token
 
-error: aborting due to 1 previous error
+warning: unused variable: `x`
+ --> $DIR/doctest-output-include-fail.md:5:9
+ |
+LL | let x = 234 // no semicolon here! oh no!
+ | ^ help: if this is intentional, prefix it with an underscore: `_x`
+ |
+ = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
+
+error: aborting due to 1 previous error; 1 warning emitted
 
 Couldn't compile the test.
 
@@ -22,4 +30,3 @@ failures:
 
 test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
 
-all doctests ran in $TIME; merged doctests compilation took $TIME

tests/rustdoc-ui/doctest/nocapture-fail.stderr

@@ -14,5 +14,12 @@ LL | Input: 123
 LL ~ } }
  |
 
-error: aborting due to 1 previous error
+error[E0601]: `main` function not found in crate `rust_out`
+ --> $DIR/nocapture-fail.rs:10:2
+ |
+LL | }
+ | ^ consider adding a `main` function to `$DIR/nocapture-fail.rs`
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0601`.

tests/rustdoc-ui/doctest/recovered-syntax-error.rs

@@ -0,0 +1,9 @@
+// issue: <https://github.com/rust-lang/rust/issues/147999>
+//@ compile-flags: --test
+//@ normalize-stdout: "tests/rustdoc-ui/doctest" -> "$$DIR"
+//@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"
+//@ failure-status: 101
+
+//! ```
+//! #[derive(Clone)]
+//! ```

tests/rustdoc-ui/doctest/recovered-syntax-error.stdout

@@ -0,0 +1,22 @@
+
+running 1 test
+test $DIR/recovered-syntax-error.rs - (line 7) ... FAILED
+
+failures:
+
+---- $DIR/recovered-syntax-error.rs - (line 7) stdout ----
+error: expected item after attributes
+ --> $DIR/recovered-syntax-error.rs:8:1
+ |
+LL | #[derive(Clone)]
+ | ^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+Couldn't compile the test.
+
+failures:
+ $DIR/recovered-syntax-error.rs - (line 7)
+
+test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+