rustdoc: remove unportable markdown lint and old parser

Follow up rust-lang#127127

Author: notriddle

Cargo.lock

@@ -558,7 +558,7 @@ dependencies = [
  "if_chain",
  "itertools",
  "parking_lot",
- "pulldown-cmark 0.11.3",
+ "pulldown-cmark",
  "quote",
  "regex",
  "rustc_tools_util 0.4.2",
@@ -2849,17 +2849,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "pulldown-cmark"
-version = "0.9.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57206b407293d2bcd3af849ce869d52068623f19e1b5ff8e8778e3309439682b"
-dependencies = [
- "bitflags",
- "memchr",
- "unicase",
-]
-
 [[package]]
 name = "pulldown-cmark"
 version = "0.11.3"
@@ -4337,7 +4326,7 @@ version = "0.0.0"
 dependencies = [
  "bitflags",
  "itertools",
- "pulldown-cmark 0.11.3",
+ "pulldown-cmark",
  "rustc_arena",
  "rustc_ast",
  "rustc_ast_pretty",
@@ -4622,7 +4611,6 @@ dependencies = [
  "indexmap",
  "itertools",
  "minifier",
- "pulldown-cmark 0.9.6",
  "pulldown-cmark-escape",
  "regex",
  "rustdoc-json-types",

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" }

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");
 }

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);
             }
         }