Auto merge of rust-lang#10357 - nindalf:doc_markdown_relax, r=llogiq

Stop doc_markdown requiring backticks on links to external websites

Fixes rust-lang#10302

This lint currently checks that any link should be enclosed with `backticks` if the title looks like a lang item. This PR changes the lint to only run on internal links. External links, indicated by `http` or `https`, are skipped.

This PR also reorganises `pulldown_cmark` imports to bypass the clippy lint enforcing 100 line functions.

---

changelog: Stop doc_markdown requiring backticks on links to external websites

clippy_lints/src/doc.rs

@@ -6,6 +6,11 @@ use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
 use clippy_utils::{is_entrypoint_fn, method_chain_args, return_ty};
 use if_chain::if_chain;
 use itertools::Itertools;
+use pulldown_cmark::Event::{
+    Code, End, FootnoteReference, HardBreak, Html, Rule, SoftBreak, Start, TaskListMarker, Text,
+};
+use pulldown_cmark::Tag::{CodeBlock, Heading, Item, Link, Paragraph};
+use pulldown_cmark::{BrokenLink, CodeBlockKind, CowStr, Options};
 use rustc_ast::ast::{Async, AttrKind, Attribute, Fn, FnRetTy, ItemKind};
 use rustc_ast::token::CommentKind;
 use rustc_data_structures::fx::FxHashSet;
@@ -497,7 +502,6 @@ struct DocHeaders {
 }
 
 fn check_attrs(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, attrs: &[Attribute]) -> Option<DocHeaders> {
-    use pulldown_cmark::{BrokenLink, CowStr, Options};
     /// We don't want the parser to choke on intra doc links. Since we don't
     /// actually care about rendering them, just pretend that all broken links are
     /// point to a fake address.
@@ -538,8 +542,6 @@ fn check_attrs(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, attrs: &[
         pulldown_cmark::Parser::new_with_broken_link_callback(&doc, Options::empty(), Some(&mut cb)).into_offset_iter();
     // Iterate over all `Events` and combine consecutive events into one
     let events = parser.coalesce(|previous, current| {
-        use pulldown_cmark::Event::Text;
-
         let previous_range = previous.1;
         let current_range = current.1;
 
@@ -564,12 +566,6 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
     spans: &[(usize, Span)],
 ) -> DocHeaders {
     // true if a safety header was found
-    use pulldown_cmark::Event::{
-        Code, End, FootnoteReference, HardBreak, Html, Rule, SoftBreak, Start, TaskListMarker, Text,
-    };
-    use pulldown_cmark::Tag::{CodeBlock, Heading, Item, Link, Paragraph};
-    use pulldown_cmark::{CodeBlockKind, CowStr};
-
     let mut headers = DocHeaders::default();
     let mut in_code = false;
     let mut in_link = None;
@@ -660,6 +656,12 @@ fn check_doc<'a, Events: Iterator<Item = (pulldown_cmark::Event<'a>, Range<usize
                     check_link_quotes(cx, in_link.is_some(), trimmed_text, span, &range, begin, text.len());
                     // Adjust for the beginning of the current `Event`
                     let span = span.with_lo(span.lo() + BytePos::from_usize(range.start - begin));
+                    if let Some(link) = in_link.as_ref()
+                      && let Ok(url) = Url::parse(link)
+                      && (url.scheme() == "https" || url.scheme() == "http") {
+                        // Don't check the text associated with external URLs
+                        continue;
+                    }
                     text_to_check.push((text, span));
                 }
             },

tests/ui/doc/doc-fixable.fixed

@@ -78,7 +78,7 @@ fn test_allowed() {
 /// This test has [a `link_with_underscores`][chunked-example] inside it. See #823.
 /// See also [the issue tracker](https://github.com/rust-lang/rust-clippy/search?q=clippy::doc_markdown&type=Issues)
 /// on GitHub (which is a camel-cased word, but is OK). And here is another [inline link][inline_link].
-/// It can also be [`inline_link2`].
+/// It can also be [inline_link2]. A link to [StackOverflow](https://stackoverflow.com) is also acceptable.
 ///
 /// [chunked-example]: https://en.wikipedia.org/wiki/Chunked_transfer_encoding#Example
 /// [inline_link]: https://foobar

tests/ui/doc/doc-fixable.rs

@@ -75,10 +75,10 @@ fn test_units() {
 fn test_allowed() {
 }
 
-/// This test has [a link_with_underscores][chunked-example] inside it. See #823.
+/// This test has [a `link_with_underscores`][chunked-example] inside it. See #823.
 /// See also [the issue tracker](https://github.com/rust-lang/rust-clippy/search?q=clippy::doc_markdown&type=Issues)
 /// on GitHub (which is a camel-cased word, but is OK). And here is another [inline link][inline_link].
-/// It can also be [inline_link2].
+/// It can also be [inline_link2]. A link to [StackOverflow](https://stackoverflow.com) is also acceptable.
 ///
 /// [chunked-example]: https://en.wikipedia.org/wiki/Chunked_transfer_encoding#Example
 /// [inline_link]: https://foobar

tests/ui/doc/doc-fixable.stderr

@@ -142,28 +142,6 @@ help: try
 LL | /// `be_sure_we_got_to_the_end_of_it`
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-error: item in documentation is missing backticks
-  --> $DIR/doc-fixable.rs:78:22
-   |
-LL | /// This test has [a link_with_underscores][chunked-example] inside it. See #823.
-   |                      ^^^^^^^^^^^^^^^^^^^^^
-   |
-help: try
-   |
-LL | /// This test has [a `link_with_underscores`][chunked-example] inside it. See #823.
-   |                      ~~~~~~~~~~~~~~~~~~~~~~~
-
-error: item in documentation is missing backticks
-  --> $DIR/doc-fixable.rs:81:21
-   |
-LL | /// It can also be [inline_link2].
-   |                     ^^^^^^^^^^^^
-   |
-help: try
-   |
-LL | /// It can also be [`inline_link2`].
-   |                     ~~~~~~~~~~~~~~
-
 error: item in documentation is missing backticks
   --> $DIR/doc-fixable.rs:91:5
    |
@@ -329,5 +307,5 @@ help: try
 LL | /// An iterator over `mycrate::Collection`'s values.
    |                      ~~~~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 30 previous errors
+error: aborting due to 28 previous errors