rustdoc: remove unportable markdown lint and old parser

Follow up https://github.com/rust-lang/rust/pull/127127

4 files changed, 1 insertions, 159 deletions

diff --git a/src/librustdoc/Cargo.toml b/src/librustdoc/Cargo.toml
index 27ae0553c60..dbfdd8ebd16 100644
--- a/src/librustdoc/Cargo.toml
+++ b/src/librustdoc/Cargo.toml
@@ -14,7 +14,6 @@ base64 = "0.21.7"
 itertools = "0.12"
 indexmap = "2"
 minifier = { version = "0.3.5", default-features = false }
-pulldown-cmark-old = { version = "0.9.6", package = "pulldown-cmark", default-features = false }
 pulldown-cmark-escape = { version = "0.11.0", features = ["simd"] }
 regex = "1"
 rustdoc-json-types = { path = "../rustdoc-json-types" }
diff --git a/src/librustdoc/lint.rs b/src/librustdoc/lint.rs
index dcc27cd62e3..b09ea056885 100644
--- a/src/librustdoc/lint.rs
+++ b/src/librustdoc/lint.rs
@@ -196,14 +196,6 @@ declare_rustdoc_lint! {
     "detects redundant explicit links in doc comments"
 }
 
-declare_rustdoc_lint! {
-    /// This compatibility lint checks for Markdown syntax that works in the old engine but not
-    /// the new one.
-    UNPORTABLE_MARKDOWN,
-    Warn,
-    "detects markdown that is interpreted differently in different parser"
-}
-
 pub(crate) static RUSTDOC_LINTS: Lazy<Vec<&'static Lint>> = Lazy::new(|| {
     vec![
         BROKEN_INTRA_DOC_LINKS,
@@ -217,7 +209,6 @@ pub(crate) static RUSTDOC_LINTS: Lazy<Vec<&'static Lint>> = Lazy::new(|| {
         MISSING_CRATE_LEVEL_DOCS,
         UNESCAPED_BACKTICKS,
         REDUNDANT_EXPLICIT_LINKS,
-        UNPORTABLE_MARKDOWN,
     ]
 });
 
@@ -241,4 +232,5 @@ pub(crate) fn register_lints(_sess: &Session, lint_store: &mut LintStore) {
         .register_renamed("intra_doc_link_resolution_failure", "rustdoc::broken_intra_doc_links");
     lint_store.register_renamed("non_autolinks", "rustdoc::bare_urls");
     lint_store.register_renamed("rustdoc::non_autolinks", "rustdoc::bare_urls");
+    lint_store.register_removed("rustdoc::unportable_markdown", "old parser removed");
 }
diff --git a/src/librustdoc/passes/lint.rs b/src/librustdoc/passes/lint.rs
index 1ecb53e61ac..7740d14148b 100644
--- a/src/librustdoc/passes/lint.rs
+++ b/src/librustdoc/passes/lint.rs
@@ -6,7 +6,6 @@ mod check_code_block_syntax;
 mod html_tags;
 mod redundant_explicit_links;
 mod unescaped_backticks;
-mod unportable_markdown;
 
 use super::Pass;
 use crate::clean::*;
@@ -49,9 +48,6 @@ impl DocVisitor<'_> for Linter<'_, '_> {
             }
             if may_have_block_comment_or_html {
                 html_tags::visit_item(self.cx, item, hir_id, &dox);
-                unportable_markdown::visit_item(self.cx, item, hir_id, &dox);
-            } else if may_have_link {
-                unportable_markdown::visit_item(self.cx, item, hir_id, &dox);
             }
         }
 
diff --git a/src/librustdoc/passes/lint/unportable_markdown.rs b/src/librustdoc/passes/lint/unportable_markdown.rs
deleted file mode 100644
index 95646413a2d..00000000000
--- a/src/librustdoc/passes/lint/unportable_markdown.rs
+++ /dev/null
@@ -1,145 +0,0 @@
-//! Detects specific markdown syntax that's different between pulldown-cmark
-//! 0.9 and 0.11.
-//!
-//! This is a mitigation for old parser bugs that affected some
-//! real crates' docs. The old parser claimed to comply with CommonMark,
-//! but it did not. These warnings will eventually be removed,
-//! though some of them may become Clippy lints.
-//!
-//! <https://github.com/rust-lang/rust/pull/121659#issuecomment-1992752820>
-//!
-//! <https://rustc-dev-guide.rust-lang.org/bug-fix-procedure.html#add-the-lint-to-the-list-of-removed-lists>
-
-use std::collections::{BTreeMap, BTreeSet};
-
-use rustc_hir::HirId;
-use rustc_lint_defs::Applicability;
-use rustc_resolve::rustdoc::source_span_for_markdown_range;
-use {pulldown_cmark as cmarkn, pulldown_cmark_old as cmarko};
-
-use crate::clean::Item;
-use crate::core::DocContext;
-
-pub(crate) fn visit_item(cx: &DocContext<'_>, item: &Item, hir_id: HirId, dox: &str) {
-    let tcx = cx.tcx;
-
-    // P1: unintended strikethrough was fixed by requiring single-tildes to flank
-    // the same way underscores do, so nothing is done here
-
-    // P2: block quotes without following space parsed wrong
-    //
-    // This is the set of starting points for block quotes with no space after
-    // the `>`. It is populated by the new parser, and if the old parser fails to
-    // clear it out, it'll produce a warning.
-    let mut spaceless_block_quotes = BTreeSet::new();
-
-    // P3: missing footnote references
-    //
-    // This is populated by listening for FootnoteReference from
-    // the new parser and old parser.
-    let mut missing_footnote_references = BTreeMap::new();
-    let mut found_footnote_references = BTreeSet::new();
-
-    // populate problem cases from new parser
-    {
-        pub fn main_body_opts_new() -> cmarkn::Options {
-            cmarkn::Options::ENABLE_TABLES
-                | cmarkn::Options::ENABLE_FOOTNOTES
-                | cmarkn::Options::ENABLE_STRIKETHROUGH
-                | cmarkn::Options::ENABLE_TASKLISTS
-                | cmarkn::Options::ENABLE_SMART_PUNCTUATION
-        }
-        let parser_new = cmarkn::Parser::new_ext(dox, main_body_opts_new()).into_offset_iter();
-        for (event, span) in parser_new {
-            if let cmarkn::Event::Start(cmarkn::Tag::BlockQuote(_)) = event {
-                if !dox[span.clone()].starts_with("> ") {
-                    spaceless_block_quotes.insert(span.start);
-                }
-            }
-            if let cmarkn::Event::FootnoteReference(_) = event {
-                found_footnote_references.insert(span.start + 1);
-            }
-        }
-    }
-
-    // remove cases where they don't actually differ
-    {
-        pub fn main_body_opts_old() -> cmarko::Options {
-            cmarko::Options::ENABLE_TABLES
-                | cmarko::Options::ENABLE_FOOTNOTES
-                | cmarko::Options::ENABLE_STRIKETHROUGH
-                | cmarko::Options::ENABLE_TASKLISTS
-                | cmarko::Options::ENABLE_SMART_PUNCTUATION
-        }
-        let parser_old = cmarko::Parser::new_ext(dox, main_body_opts_old()).into_offset_iter();
-        for (event, span) in parser_old {
-            if let cmarko::Event::Start(cmarko::Tag::BlockQuote) = event
-                && !dox[span.clone()].starts_with("> ")
-            {
-                spaceless_block_quotes.remove(&span.start);
-            }
-            if let cmarko::Event::FootnoteReference(_) = event
-                && !found_footnote_references.contains(&(span.start + 1))
-            {
-                missing_footnote_references.insert(span.start + 1, span);
-            }
-        }
-    }
-
-    for start in spaceless_block_quotes {
-        let (span, precise) =
-            source_span_for_markdown_range(tcx, dox, &(start..start + 1), &item.attrs.doc_strings)
-                .map(|span| (span, true))
-                .unwrap_or_else(|| (item.attr_span(tcx), false));
-
-        tcx.node_span_lint(crate::lint::UNPORTABLE_MARKDOWN, hir_id, span, |lint| {
-            lint.primary_message("unportable markdown");
-            lint.help("confusing block quote with no space after the `>` marker".to_string());
-            if precise {
-                lint.span_suggestion(
-                    span.shrink_to_hi(),
-                    "if the quote is intended, add a space",
-                    " ",
-                    Applicability::MaybeIncorrect,
-                );
-                lint.span_suggestion(
-                    span.shrink_to_lo(),
-                    "if it should not be a quote, escape it",
-                    "\\",
-                    Applicability::MaybeIncorrect,
-                );
-            }
-        });
-    }
-    for (_caret, span) in missing_footnote_references {
-        let (ref_span, precise) =
-            source_span_for_markdown_range(tcx, dox, &span, &item.attrs.doc_strings)
-                .map(|span| (span, true))
-                .unwrap_or_else(|| (item.attr_span(tcx), false));
-
-        tcx.node_span_lint(crate::lint::UNPORTABLE_MARKDOWN, hir_id, ref_span, |lint| {
-            lint.primary_message("unportable markdown");
-            if precise {
-                lint.span_suggestion(
-                    ref_span.shrink_to_lo(),
-                    "if it should not be a footnote, escape it",
-                    "\\",
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            if dox.as_bytes().get(span.end) == Some(&b'[') {
-                lint.help("confusing footnote reference and link");
-                if precise {
-                    lint.span_suggestion(
-                        ref_span.shrink_to_hi(),
-                        "if the footnote is intended, add a space",
-                        " ",
-                        Applicability::MaybeIncorrect,
-                    );
-                } else {
-                    lint.help("there should be a space between the link and the footnote");
-                }
-            }
-        });
-    }
-}