Rollup of 4 pull requests

compiler/rustc_lint/src/lib.rs

@@ -70,7 +70,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::{
     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
-    MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
+    INVALID_RUST_CODEBLOCK, MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
 };
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
@@ -319,6 +319,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_DOC_CODE_EXAMPLES,
         PRIVATE_DOC_TESTS,
         INVALID_HTML_TAGS

compiler/rustc_lint_defs/src/builtin.rs

@@ -1846,6 +1846,18 @@ declare_lint! {
     "codeblock attribute looks a lot like a known one"
 }
 
+declare_lint! {
+    /// The `invalid_rust_codeblock` lint detects Rust code blocks in
+    /// documentation examples that are invalid (e.g. empty, not parsable as
+    /// Rust code). This is a `rustdoc` only lint, see the documentation in the
+    /// [rustdoc book].
+    ///
+    /// [rustdoc book]: ../../../rustdoc/lints.html#invalid_rust_codeblock
+    pub INVALID_RUST_CODEBLOCK,
+    Warn,
+    "codeblock could not be parsed as valid Rust or is empty"
+}
+
 declare_lint! {
     /// The `missing_crate_level_docs` lint detects if documentation is
     /// missing at the crate root. This is a `rustdoc` only lint, see the
@@ -2846,6 +2858,7 @@ declare_lint_pass! {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_CRATE_LEVEL_DOCS,
         MISSING_DOC_CODE_EXAMPLES,
         INVALID_HTML_TAGS,

compiler/rustc_middle/src/ty/sty.rs

@@ -215,10 +215,7 @@ pub enum TyKind<'tcx> {
 impl TyKind<'tcx> {
     #[inline]
     pub fn is_primitive(&self) -> bool {
-        match self {
-            Bool | Char | Int(_) | Uint(_) | Float(_) => true,
-            _ => false,
-        }
+        matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
     }
 
     /// Get the article ("a" or "an") to use with this type.

compiler/rustc_trait_selection/src/opaque_types.rs

@@ -46,6 +46,7 @@ pub struct OpaqueTypeDecl<'tcx> {
     /// type Foo = impl Baz;
     /// fn bar() -> Foo {
     /// //          ^^^ This is the span we are looking for!
+    /// # }
     /// ```
     ///
     /// In cases where the fn returns `(impl Trait, impl Trait)` or

src/bootstrap/doc.rs

@@ -628,6 +628,8 @@ impl Step for Rustdoc {
         cargo.arg("-p").arg("rustdoc");
 
         cargo.rustdocflag("--document-private-items");
+        cargo.rustdocflag("--enable-index-page");
+        cargo.rustdocflag("-Zunstable-options");
         builder.run(&mut cargo.into());
     }
 }

src/doc/rustdoc/src/lints.md

@@ -285,6 +285,41 @@ warning: unclosed HTML tag `h1`
 
 warning: 2 warnings emitted
 ```
+
+## invalid_rust_codeblock
+
+This lint **warns by default**. It detects Rust code blocks in documentation
+examples that are invalid (e.g. empty, not parsable as Rust). For example:
+
+```rust
+/// Empty code block, with and without Rust:
+///
+/// ```rust
+/// ```
+///
+/// Unclosed code block:
+///
+/// ```rust
+fn main() {}
+```
+
+Which will give:
+
+```text
+warning: Rust code block is empty
+ --> src/lib.rs:3:5
+  |
+3 |   /// ```rust
+  |  _____^
+4 | | /// ```
+  | |_______^
+
+warning: Rust code block is empty
+ --> src/lib.rs:8:5
+  |
+8 | /// ```rust
+  |     ^^^^^^^
+```
 
 ## non_autolinks
 

src/librustdoc/core.rs

@@ -308,6 +308,7 @@ crate fn create_config(
     let private_doc_tests = rustc_lint::builtin::PRIVATE_DOC_TESTS.name;
     let no_crate_level_docs = rustc_lint::builtin::MISSING_CRATE_LEVEL_DOCS.name;
     let invalid_codeblock_attributes_name = rustc_lint::builtin::INVALID_CODEBLOCK_ATTRIBUTES.name;
+    let invalid_rust_codeblock = rustc_lint::builtin::INVALID_RUST_CODEBLOCK.name;
     let invalid_html_tags = rustc_lint::builtin::INVALID_HTML_TAGS.name;
     let renamed_and_removed_lints = rustc_lint::builtin::RENAMED_AND_REMOVED_LINTS.name;
     let non_autolinks = rustc_lint::builtin::NON_AUTOLINKS.name;
@@ -323,6 +324,7 @@ crate fn create_config(
         private_doc_tests.to_owned(),
         no_crate_level_docs.to_owned(),
         invalid_codeblock_attributes_name.to_owned(),
+        invalid_rust_codeblock.to_owned(),
         invalid_html_tags.to_owned(),
         renamed_and_removed_lints.to_owned(),
         unknown_lints.to_owned(),

src/librustdoc/html/highlight.rs

@@ -11,7 +11,8 @@ use std::fmt::{Display, Write};
 use std::iter::Peekable;
 
 use rustc_lexer::{LiteralKind, TokenKind};
-use rustc_span::symbol::Ident;
+use rustc_span::edition::Edition;
+use rustc_span::symbol::Symbol;
 use rustc_span::with_default_session_globals;
 
 /// Highlights `src`, returning the HTML output.
@@ -20,6 +21,7 @@ crate fn render_with_highlighting(
     class: Option<&str>,
     playground_button: Option<&str>,
     tooltip: Option<(&str, &str)>,
+    edition: Edition,
 ) -> String {
     debug!("highlighting: ================\n{}\n==============", src);
     let mut out = String::with_capacity(src.len());
@@ -34,7 +36,7 @@ crate fn render_with_highlighting(
     }
 
     write_header(&mut out, class);
-    write_code(&mut out, &src);
+    write_code(&mut out, &src, edition);
     write_footer(&mut out, playground_button);
 
     out
@@ -45,10 +47,10 @@ fn write_header(out: &mut String, class: Option<&str>) {
         .unwrap()
 }
 
-fn write_code(out: &mut String, src: &str) {
+fn write_code(out: &mut String, src: &str, edition: Edition) {
     // This replace allows to fix how the code source with DOS backline characters is displayed.
     let src = src.replace("\r\n", "\n");
-    Classifier::new(&src).highlight(&mut |highlight| {
+    Classifier::new(&src, edition).highlight(&mut |highlight| {
         match highlight {
             Highlight::Token { text, class } => string(out, Escape(text), class),
             Highlight::EnterSpan { class } => enter_span(out, class),
@@ -139,12 +141,19 @@ struct Classifier<'a> {
     in_attribute: bool,
     in_macro: bool,
     in_macro_nonterminal: bool,
+    edition: Edition,
 }
 
 impl<'a> Classifier<'a> {
-    fn new(src: &str) -> Classifier<'_> {
+    fn new(src: &str, edition: Edition) -> Classifier<'_> {
         let tokens = TokenIter { src }.peekable();
-        Classifier { tokens, in_attribute: false, in_macro: false, in_macro_nonterminal: false }
+        Classifier {
+            tokens,
+            in_attribute: false,
+            in_macro: false,
+            in_macro_nonterminal: false,
+            edition,
+        }
     }
 
     /// Exhausts the `Classifier` writing the output into `sink`.
@@ -296,7 +305,7 @@ impl<'a> Classifier<'a> {
                 "Option" | "Result" => Class::PreludeTy,
                 "Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
                 // Keywords are also included in the identifier set.
-                _ if Ident::from_str(text).is_reserved() => Class::KeyWord,
+                _ if Symbol::intern(text).is_reserved(|| self.edition) => Class::KeyWord,
                 _ if self.in_macro_nonterminal => {
                     self.in_macro_nonterminal = false;
                     Class::MacroNonTerminal

src/librustdoc/html/highlight/tests.rs

@@ -1,5 +1,6 @@
 use super::write_code;
 use expect_test::expect_file;
+use rustc_span::edition::Edition;
 
 const STYLE: &str = r#"
 <style>
@@ -18,7 +19,7 @@ fn test_html_highlighting() {
     let src = include_str!("fixtures/sample.rs");
     let html = {
         let mut out = String::new();
-        write_code(&mut out, src);
+        write_code(&mut out, src, Edition::Edition2018);
         format!("{}<pre><code>{}</code></pre>\n", STYLE, out)
     };
     expect_file!["fixtures/sample.html"].assert_eq(&html);
@@ -30,6 +31,6 @@ fn test_dos_backline() {
     println!(\"foo\");\r\n\
 }\r\n";
     let mut html = String::new();
-    write_code(&mut html, src);
+    write_code(&mut html, src, Edition::Edition2018);
     expect_file!["fixtures/dos_line.html"].assert_eq(&html);
 }

src/librustdoc/html/markdown.rs

@@ -314,6 +314,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                 )),
                 playground_button.as_deref(),
                 Some((s1.as_str(), s2)),
+                edition,
             ));
             Some(Event::Html(s.into()))
         } else {
@@ -335,6 +336,7 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                 )),
                 playground_button.as_deref(),
                 None,
+                edition,
             ));
             Some(Event::Html(s.into()))
         }

src/librustdoc/html/render/mod.rs

@@ -4747,6 +4747,7 @@ fn item_macro(w: &mut Buffer, cx: &Context<'_>, it: &clean::Item, t: &clean::Mac
             Some("macro"),
             None,
             None,
+            it.source.span().edition(),
         ))
     });
     document(w, cx, it, None)

src/librustdoc/html/sources.rs

@@ -8,6 +8,7 @@ use crate::html::layout;
 use crate::html::render::{SharedContext, BASIC_KEYWORDS};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_session::Session;
+use rustc_span::edition::Edition;
 use rustc_span::source_map::FileName;
 use std::ffi::OsStr;
 use std::fs;
@@ -132,7 +133,7 @@ impl SourceCollector<'_, '_> {
             &self.scx.layout,
             &page,
             "",
-            |buf: &mut _| print_src(buf, contents),
+            |buf: &mut _| print_src(buf, contents, self.scx.edition),
             &self.scx.style_files,
         );
         self.scx.fs.write(&cur, v.as_bytes())?;
@@ -170,7 +171,7 @@ where
 
 /// Wrapper struct to render the source code of a file. This will do things like
 /// adding line numbers to the left-hand side.
-fn print_src(buf: &mut Buffer, s: String) {
+fn print_src(buf: &mut Buffer, s: String, edition: Edition) {
     let lines = s.lines().count();
     let mut cols = 0;
     let mut tmp = lines;
@@ -183,5 +184,5 @@ fn print_src(buf: &mut Buffer, s: String) {
         write!(buf, "<span id=\"{0}\">{0:1$}</span>\n", i, cols);
     }
     write!(buf, "</pre>");
-    write!(buf, "{}", highlight::render_with_highlighting(s, None, None, None));
+    write!(buf, "{}", highlight::render_with_highlighting(s, None, None, None, edition));
 }

src/librustdoc/passes/check_code_block_syntax.rs

@@ -1,6 +1,8 @@
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_errors::{emitter::Emitter, Applicability, Diagnostic, Handler};
+use rustc_middle::lint::LintDiagnosticBuilder;
 use rustc_parse::parse_stream_from_source_str;
+use rustc_session::lint;
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
 use rustc_span::{FileName, InnerSpan};
@@ -47,51 +49,76 @@ impl<'a, 'tcx> SyntaxChecker<'a, 'tcx> {
         .unwrap_or(false);
         let buffer = buffer.borrow();
 
-        if buffer.has_errors || is_empty {
-            let mut diag = if let Some(sp) =
-                super::source_span_for_markdown_range(self.cx, &dox, &code_block.range, &item.attrs)
-            {
-                let warning_message = if buffer.has_errors {
+        if !(buffer.has_errors || is_empty) {
+            // No errors in a non-empty program.
+            return;
+        }
+
+        let local_id = match item.def_id.as_local() {
+            Some(id) => id,
+            // We don't need to check the syntax for other crates so returning
+            // without doing anything should not be a problem.
+            None => return,
+        };
+
+        let hir_id = self.cx.tcx.hir().local_def_id_to_hir_id(local_id);
+        let mark_with_text = code_block.syntax.is_none() && code_block.is_fenced;
+
+        // The span and whether it is precise or not.
+        let (sp, precise_span) = match super::source_span_for_markdown_range(
+            self.cx,
+            &dox,
+            &code_block.range,
+            &item.attrs,
+        ) {
+            Some(sp) => (sp, true),
+            None => (super::span_of_attrs(&item.attrs).unwrap_or(item.source.span()), false),
+        };
+
+        // lambda that will use the lint to start a new diagnostic and add
+        // a suggestion to it when needed.
+        let diag_builder = |lint: LintDiagnosticBuilder<'_>| {
+            let mut diag = if precise_span {
+                let msg = if buffer.has_errors {
                     "could not parse code block as Rust code"
                 } else {
                     "Rust code block is empty"
                 };
 
-                let mut diag = self.cx.sess().struct_span_warn(sp, warning_message);
-
-                if code_block.syntax.is_none() && code_block.is_fenced {
-                    let sp = sp.from_inner(InnerSpan::new(0, 3));
+                let mut diag = lint.build(msg);
+                if mark_with_text {
                     diag.span_suggestion(
-                        sp,
+                        sp.from_inner(InnerSpan::new(0, 3)),
                         "mark blocks that do not contain Rust code as text",
                         String::from("```text"),
                         Applicability::MachineApplicable,
                     );
                 }
-
                 diag
             } else {
-                // We couldn't calculate the span of the markdown block that had the error, so our
-                // diagnostics are going to be a bit lacking.
-                let mut diag = self.cx.sess().struct_span_warn(
-                    super::span_of_attrs(&item.attrs).unwrap_or(item.source.span()),
-                    "doc comment contains an invalid Rust code block",
-                );
-
-                if code_block.syntax.is_none() && code_block.is_fenced {
+                let mut diag = lint.build("doc comment contains an invalid Rust code block");
+                if mark_with_text {
                     diag.help("mark blocks that do not contain Rust code as text: ```text");
                 }
 
                 diag
             };
-
             // FIXME(#67563): Provide more context for these errors by displaying the spans inline.
             for message in buffer.messages.iter() {
                 diag.note(&message);
             }
-
             diag.emit();
-        }
+        };
+
+        // Finally build and emit the completed diagnostic.
+        // All points of divergence have been handled earlier so this can be
+        // done the same way whether the span is precise or not.
+        self.cx.tcx.struct_span_lint_hir(
+            lint::builtin::INVALID_RUST_CODEBLOCK,
+            hir_id,
+            sp,
+            diag_builder,
+        );
     }
 }
 

src/test/rustdoc-ui/invalid-syntax.stderr

@@ -7,6 +7,7 @@ LL | | /// \__________pkt->size___________/          \_result->size_/ \__pkt->si
 LL | | /// ```
    | |_______^
    |
+   = note: `#[warn(invalid_rust_codeblock)]` on by default
    = note: error from rustc: unknown start of token: \
    = note: error from rustc: unknown start of token: \
    = note: error from rustc: unknown start of token: \