compiler/rustc_resolve/src/rustdoc.rs - toolchain/rustc - Git at Google

 use pulldown_cmark::{BrokenLink, CowStr, Event, LinkType, Options, Parser, Tag};
 use rustc_ast as ast;
 use rustc_ast::util::comments::beautify_doc_string;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::{InnerSpan, Span, DUMMY_SP};
 use std::ops::Range;
 use std::{cmp, mem};

 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub enum DocFragmentKind {
     /// A doc fragment created from a `///` or `//!` doc comment.
     SugaredDoc,
     /// A doc fragment created from a "raw" `#[doc=""]` attribute.
     RawDoc,
 }

 /// A portion of documentation, extracted from a `#[doc]` attribute.
 ///
 /// Each variant contains the line number within the complete doc-comment where the fragment
 /// starts, as well as the Span where the corresponding doc comment or attribute is located.
 ///
 /// Included files are kept separate from inline doc comments so that proper line-number
 /// information can be given when a doctest fails. Sugared doc comments and "raw" doc comments are
 /// kept separate because of issue #42760.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct DocFragment {
     pub span: Span,
     /// The item this doc-comment came from.
     /// Used to determine the scope in which doc links in this fragment are resolved.
     /// Typically filled for reexport docs when they are merged into the docs of the
     /// original reexported item.
     /// If the id is not filled, which happens for the original reexported item, then
     /// it has to be taken from somewhere else during doc link resolution.
     pub item_id: Option<DefId>,
     pub doc: Symbol,
     pub kind: DocFragmentKind,
     pub indent: usize,
 }

 #[derive(Clone, Copy, Debug)]
 pub enum MalformedGenerics {
     /// This link has unbalanced angle brackets.
     ///
     /// For example, `Vec<T` should trigger this, as should `Vec<T>>`.
     UnbalancedAngleBrackets,
     /// The generics are not attached to a type.
     ///
     /// For example, `<T>` should trigger this.
     ///
     /// This is detected by checking if the path is empty after the generics are stripped.
     MissingType,
     /// The link uses fully-qualified syntax, which is currently unsupported.
     ///
     /// For example, `<Vec as IntoIterator>::into_iter` should trigger this.
     ///
     /// This is detected by checking if ` as ` (the keyword `as` with spaces around it) is inside
     /// angle brackets.
     HasFullyQualifiedSyntax,
     /// The link has an invalid path separator.
     ///
     /// For example, `Vec:<T>:new()` should trigger this. Note that `Vec:new()` will **not**
     /// trigger this because it has no generics and thus [`strip_generics_from_path`] will not be
     /// called.
     ///
     /// Note that this will also **not** be triggered if the invalid path separator is inside angle
     /// brackets because rustdoc mostly ignores what's inside angle brackets (except for
     /// [`HasFullyQualifiedSyntax`](MalformedGenerics::HasFullyQualifiedSyntax)).
     ///
     /// This is detected by checking if there is a colon followed by a non-colon in the link.
     InvalidPathSeparator,
     /// The link has too many angle brackets.
     ///
     /// For example, `Vec<<T>>` should trigger this.
     TooManyAngleBrackets,
     /// The link has empty angle brackets.
     ///
     /// For example, `Vec<>` should trigger this.
     EmptyAngleBrackets,
 }

 /// Removes excess indentation on comments in order for the Markdown
 /// to be parsed correctly. This is necessary because the convention for
 /// writing documentation is to provide a space between the /// or //! marker
 /// and the doc text, but Markdown is whitespace-sensitive. For example,
 /// a block of text with four-space indentation is parsed as a code block,
 /// so if we didn't unindent comments, these list items
 ///
 /// /// A list:
 /// ///
 /// ///    - Foo
 /// ///    - Bar
 ///
 /// would be parsed as if they were in a code block, which is likely not what the user intended.
 pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
     // `add` is used in case the most common sugared doc syntax is used ("/// "). The other
     // fragments kind's lines are never starting with a whitespace unless they are using some
     // markdown formatting requiring it. Therefore, if the doc block have a mix between the two,
     // we need to take into account the fact that the minimum indent minus one (to take this
     // whitespace into account).
     //
     // For example:
     //
     // /// hello!
     // #[doc = "another"]
     //
     // In this case, you want "hello! another" and not "hello!  another".
     let add = if docs.windows(2).any(|arr| arr[0].kind != arr[1].kind)
         && docs.iter().any(|d| d.kind == DocFragmentKind::SugaredDoc)
     {
         // In case we have a mix of sugared doc comments and "raw" ones, we want the sugared one to
         // "decide" how much the minimum indent will be.
         1
     } else {
         0
     };

     // `min_indent` is used to know how much whitespaces from the start of each lines must be
     // removed. Example:
     //
     // ///     hello!
     // #[doc = "another"]
     //
     // In here, the `min_indent` is 1 (because non-sugared fragment are always counted with minimum
     // 1 whitespace), meaning that "hello!" will be considered a codeblock because it starts with 4
     // (5 - 1) whitespaces.
     let Some(min_indent) = docs
         .iter()
         .map(|fragment| {
             fragment.doc.as_str().lines().fold(usize::MAX, |min_indent, line| {
                 if line.chars().all(|c| c.is_whitespace()) {
                     min_indent
                 } else {
                     // Compare against either space or tab, ignoring whether they are
                     // mixed or not.
                     let whitespace = line.chars().take_while(|c| *c == ' ' || *c == '\t').count();
                     cmp::min(min_indent, whitespace)
                         + if fragment.kind == DocFragmentKind::SugaredDoc { 0 } else { add }
                 }
             })
         })
         .min()
     else {
         return;
     };

     for fragment in docs {
         if fragment.doc == kw::Empty {
             continue;
         }

         let min_indent = if fragment.kind != DocFragmentKind::SugaredDoc && min_indent > 0 {
             min_indent - add
         } else {
             min_indent
         };

         fragment.indent = min_indent;
     }
 }

 /// The goal of this function is to apply the `DocFragment` transformation that is required when
 /// transforming into the final Markdown, which is applying the computed indent to each line in
 /// each doc fragment (a `DocFragment` can contain multiple lines in case of `#[doc = ""]`).
 ///
 /// Note: remove the trailing newline where appropriate
 pub fn add_doc_fragment(out: &mut String, frag: &DocFragment) {
     let s = frag.doc.as_str();
     let mut iter = s.lines();
     if s.is_empty() {
         out.push('\n');
         return;
     }
     while let Some(line) = iter.next() {
         if line.chars().any(|c| !c.is_whitespace()) {
             assert!(line.len() >= frag.indent);
             out.push_str(&line[frag.indent..]);
         } else {
             out.push_str(line);
         }
         out.push('\n');
     }
 }

 pub fn attrs_to_doc_fragments<'a>(
     attrs: impl Iterator<Item = (&'a ast::Attribute, Option<DefId>)>,
     doc_only: bool,
 ) -> (Vec<DocFragment>, ast::AttrVec) {
     let mut doc_fragments = Vec::new();
     let mut other_attrs = ast::AttrVec::new();
     for (attr, item_id) in attrs {
         if let Some((doc_str, comment_kind)) = attr.doc_str_and_comment_kind() {
             let doc = beautify_doc_string(doc_str, comment_kind);
             let kind = if attr.is_doc_comment() {
                 DocFragmentKind::SugaredDoc
             } else {
                 DocFragmentKind::RawDoc
             };
             let fragment = DocFragment { span: attr.span, doc, kind, item_id, indent: 0 };
             doc_fragments.push(fragment);
         } else if !doc_only {
             other_attrs.push(attr.clone());
         }
     }

     unindent_doc_fragments(&mut doc_fragments);

     (doc_fragments, other_attrs)
 }

 /// Return the doc-comments on this item, grouped by the module they came from.
 /// The module can be different if this is a re-export with added documentation.
 ///
 /// The last newline is not trimmed so the produced strings are reusable between
 /// early and late doc link resolution regardless of their position.
 pub fn prepare_to_doc_link_resolution(
     doc_fragments: &[DocFragment],
 ) -> FxHashMap<Option<DefId>, String> {
     let mut res = FxHashMap::default();
     for fragment in doc_fragments {
         let out_str = res.entry(fragment.item_id).or_default();
         add_doc_fragment(out_str, fragment);
     }
     res
 }

 /// Options for rendering Markdown in the main body of documentation.
 pub fn main_body_opts() -> Options {
     Options::ENABLE_TABLES
         | Options::ENABLE_FOOTNOTES
         | Options::ENABLE_STRIKETHROUGH
         | Options::ENABLE_TASKLISTS
         | Options::ENABLE_SMART_PUNCTUATION
 }

 fn strip_generics_from_path_segment(segment: Vec<char>) -> Result<String, MalformedGenerics> {
     let mut stripped_segment = String::new();
     let mut param_depth = 0;

     let mut latest_generics_chunk = String::new();

     for c in segment {
         if c == '<' {
             param_depth += 1;
             latest_generics_chunk.clear();
         } else if c == '>' {
             param_depth -= 1;
             if latest_generics_chunk.contains(" as ") {
                 // The segment tries to use fully-qualified syntax, which is currently unsupported.
                 // Give a helpful error message instead of completely ignoring the angle brackets.
                 return Err(MalformedGenerics::HasFullyQualifiedSyntax);
             }
         } else {
             if param_depth == 0 {
                 stripped_segment.push(c);
             } else {
                 latest_generics_chunk.push(c);
             }
         }
     }

     if param_depth == 0 {
         Ok(stripped_segment)
     } else {
         // The segment has unbalanced angle brackets, e.g. `Vec<T` or `Vec<T>>`
         Err(MalformedGenerics::UnbalancedAngleBrackets)
     }
 }

 pub fn strip_generics_from_path(path_str: &str) -> Result<Box<str>, MalformedGenerics> {
     if !path_str.contains(['<', '>']) {
         return Ok(path_str.into());
     }
     let mut stripped_segments = vec![];
     let mut path = path_str.chars().peekable();
     let mut segment = Vec::new();

     while let Some(chr) = path.next() {
         match chr {
             ':' => {
                 if path.next_if_eq(&':').is_some() {
                     let stripped_segment =
                         strip_generics_from_path_segment(mem::take(&mut segment))?;
                     if !stripped_segment.is_empty() {
                         stripped_segments.push(stripped_segment);
                     }
                 } else {
                     return Err(MalformedGenerics::InvalidPathSeparator);
                 }
             }
             '<' => {
                 segment.push(chr);

                 match path.next() {
                     Some('<') => {
                         return Err(MalformedGenerics::TooManyAngleBrackets);
                     }
                     Some('>') => {
                         return Err(MalformedGenerics::EmptyAngleBrackets);
                     }
                     Some(chr) => {
                         segment.push(chr);

                         while let Some(chr) = path.next_if(|c| *c != '>') {
                             segment.push(chr);
                         }
                     }
                     None => break,
                 }
             }
             _ => segment.push(chr),
         }
         trace!("raw segment: {:?}", segment);
     }

     if !segment.is_empty() {
         let stripped_segment = strip_generics_from_path_segment(segment)?;
         if !stripped_segment.is_empty() {
             stripped_segments.push(stripped_segment);
         }
     }

     debug!("path_str: {:?}\nstripped segments: {:?}", path_str, &stripped_segments);

     let stripped_path = stripped_segments.join("::");

     if !stripped_path.is_empty() {
         Ok(stripped_path.into())
     } else {
         Err(MalformedGenerics::MissingType)
     }
 }

 /// Returns whether the first doc-comment is an inner attribute.
 ///
 //// If there are no doc-comments, return true.
 /// FIXME(#78591): Support both inner and outer attributes on the same item.
 pub fn inner_docs(attrs: &[ast::Attribute]) -> bool {
     attrs.iter().find(|a| a.doc_str().is_some()).map_or(true, |a| a.style == ast::AttrStyle::Inner)
 }

 /// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]`.
 pub fn has_primitive_or_keyword_docs(attrs: &[ast::Attribute]) -> bool {
     for attr in attrs {
         if attr.has_name(sym::rustc_doc_primitive) {
             return true;
         } else if attr.has_name(sym::doc)
             && let Some(items) = attr.meta_item_list()
         {
             for item in items {
                 if item.has_name(sym::keyword) {
                     return true;
                 }
             }
         }
     }
     false
 }

 /// Simplified version of the corresponding function in rustdoc.
 /// If the rustdoc version returns a successful result, this function must return the same result.
 /// Otherwise this function may return anything.
 fn preprocess_link(link: &str) -> Box<str> {
     let link = link.replace('`', "");
     let link = link.split('#').next().unwrap();
     let link = link.trim();
     let link = link.rsplit('@').next().unwrap();
     let link = link.strip_suffix("()").unwrap_or(link);
     let link = link.strip_suffix("{}").unwrap_or(link);
     let link = link.strip_suffix("[]").unwrap_or(link);
     let link = if link != "!" { link.strip_suffix('!').unwrap_or(link) } else { link };
     let link = link.trim();
     strip_generics_from_path(link).unwrap_or_else(|_| link.into())
 }

 /// Keep inline and reference links `[]`,
 /// but skip autolinks `<>` which we never consider to be intra-doc links.
 pub fn may_be_doc_link(link_type: LinkType) -> bool {
     match link_type {
         LinkType::Inline
         | LinkType::Reference
         | LinkType::ReferenceUnknown
         | LinkType::Collapsed
         | LinkType::CollapsedUnknown
         | LinkType::Shortcut
         | LinkType::ShortcutUnknown => true,
         LinkType::Autolink | LinkType::Email => false,
     }
 }

 /// Simplified version of `preprocessed_markdown_links` from rustdoc.
 /// Must return at least the same links as it, but may add some more links on top of that.
 pub(crate) fn attrs_to_preprocessed_links(attrs: &[ast::Attribute]) -> Vec<Box<str>> {
     let (doc_fragments, _) = attrs_to_doc_fragments(attrs.iter().map(|attr| (attr, None)), true);
     let doc = prepare_to_doc_link_resolution(&doc_fragments).into_values().next().unwrap();

     parse_links(&doc)
 }

 /// Similiar version of `markdown_links` from rustdoc.
 /// This will collect destination links and display text if exists.
 fn parse_links<'md>(doc: &'md str) -> Vec<Box<str>> {
     let mut broken_link_callback = |link: BrokenLink<'md>| Some((link.reference, "".into()));
     let mut event_iter = Parser::new_with_broken_link_callback(
         &doc,
         main_body_opts(),
         Some(&mut broken_link_callback),
     )
     .into_iter();
     let mut links = Vec::new();

     while let Some(event) = event_iter.next() {
         match event {
             Event::Start(Tag::Link(link_type, dest, _)) if may_be_doc_link(link_type) => {
                 if matches!(
                     link_type,
                     LinkType::Inline
                         | LinkType::ReferenceUnknown
                         | LinkType::Reference
                         | LinkType::Shortcut
                         | LinkType::ShortcutUnknown
                 ) {
                     if let Some(display_text) = collect_link_data(&mut event_iter) {
                         links.push(display_text);
                     }
                 }

                 links.push(preprocess_link(&dest));
             }
             _ => {}
         }
     }

     links
 }

 /// Collects additional data of link.
 fn collect_link_data<'input, 'callback>(
     event_iter: &mut Parser<'input, 'callback>,
 ) -> Option<Box<str>> {
     let mut display_text: Option<String> = None;
     let mut append_text = |text: CowStr<'_>| {
         if let Some(display_text) = &mut display_text {
             display_text.push_str(&text);
         } else {
             display_text = Some(text.to_string());
         }
     };

     while let Some(event) = event_iter.next() {
         match event {
             Event::Text(text) => {
                 append_text(text);
             }
             Event::Code(code) => {
                 append_text(code);
             }
             Event::End(_) => {
                 break;
             }
             _ => {}
         }
     }

     display_text.map(String::into_boxed_str)
 }

 /// Returns a span encompassing all the document fragments.
 pub fn span_of_fragments(fragments: &[DocFragment]) -> Option<Span> {
     if fragments.is_empty() {
         return None;
     }
     let start = fragments[0].span;
     if start == DUMMY_SP {
         return None;
     }
     let end = fragments.last().expect("no doc strings provided").span;
     Some(start.to(end))
 }

 /// Attempts to match a range of bytes from parsed markdown to a `Span` in the source code.
 ///
 /// This method will return `None` if we cannot construct a span from the source map or if the
 /// fragments are not all sugared doc comments. It's difficult to calculate the correct span in
 /// that case due to escaping and other source features.
 pub fn source_span_for_markdown_range(
     tcx: TyCtxt<'_>,
     markdown: &str,
     md_range: &Range<usize>,
     fragments: &[DocFragment],
 ) -> Option<Span> {
     let is_all_sugared_doc = fragments.iter().all(|frag| frag.kind == DocFragmentKind::SugaredDoc);

     if !is_all_sugared_doc {
         return None;
     }

     let snippet = tcx.sess.source_map().span_to_snippet(span_of_fragments(fragments)?).ok()?;

     let starting_line = markdown[..md_range.start].matches('\n').count();
     let ending_line = starting_line + markdown[md_range.start..md_range.end].matches('\n').count();

     // We use `split_terminator('\n')` instead of `lines()` when counting bytes so that we treat
     // CRLF and LF line endings the same way.
     let mut src_lines = snippet.split_terminator('\n');
     let md_lines = markdown.split_terminator('\n');

     // The number of bytes from the source span to the markdown span that are not part
     // of the markdown, like comment markers.
     let mut start_bytes = 0;
     let mut end_bytes = 0;

     'outer: for (line_no, md_line) in md_lines.enumerate() {
         loop {
             let source_line = src_lines.next()?;
             match source_line.find(md_line) {
                 Some(offset) => {
                     if line_no == starting_line {
                         start_bytes += offset;

                         if starting_line == ending_line {
                             break 'outer;
                         }
                     } else if line_no == ending_line {
                         end_bytes += offset;
                         break 'outer;
                     } else if line_no < starting_line {
                         start_bytes += source_line.len() - md_line.len();
                     } else {
                         end_bytes += source_line.len() - md_line.len();
                     }
                     break;
                 }
                 None => {
                     // Since this is a source line that doesn't include a markdown line,
                     // we have to count the newline that we split from earlier.
                     if line_no <= starting_line {
                         start_bytes += source_line.len() + 1;
                     } else {
                         end_bytes += source_line.len() + 1;
                     }
                 }
             }
         }
     }

     Some(span_of_fragments(fragments)?.from_inner(InnerSpan::new(
         md_range.start + start_bytes,
         md_range.end + start_bytes + end_bytes,
     )))
 }
	use pulldown_cmark::{BrokenLink, CowStr, Event, LinkType, Options, Parser, Tag};
	use rustc_ast as ast;
	use rustc_ast::util::comments::beautify_doc_string;
	use rustc_data_structures::fx::FxHashMap;
	use rustc_middle::ty::TyCtxt;
	use rustc_span::def_id::DefId;
	use rustc_span::symbol::{kw, sym, Symbol};
	use rustc_span::{InnerSpan, Span, DUMMY_SP};
	use std::ops::Range;
	use std::{cmp, mem};

	#[derive(Clone, Copy, PartialEq, Eq, Debug)]
	pub enum DocFragmentKind {
	/// A doc fragment created from a `///` or `//!` doc comment.
	SugaredDoc,
	/// A doc fragment created from a "raw" `#[doc=""]` attribute.
	RawDoc,
	}

	/// A portion of documentation, extracted from a `#[doc]` attribute.
	///
	/// Each variant contains the line number within the complete doc-comment where the fragment
	/// starts, as well as the Span where the corresponding doc comment or attribute is located.
	///
	/// Included files are kept separate from inline doc comments so that proper line-number
	/// information can be given when a doctest fails. Sugared doc comments and "raw" doc comments are
	/// kept separate because of issue #42760.
	#[derive(Clone, PartialEq, Eq, Debug)]
	pub struct DocFragment {
	pub span: Span,
	/// The item this doc-comment came from.
	/// Used to determine the scope in which doc links in this fragment are resolved.
	/// Typically filled for reexport docs when they are merged into the docs of the
	/// original reexported item.
	/// If the id is not filled, which happens for the original reexported item, then
	/// it has to be taken from somewhere else during doc link resolution.
	pub item_id: Option<DefId>,
	pub doc: Symbol,
	pub kind: DocFragmentKind,
	pub indent: usize,
	}

	#[derive(Clone, Copy, Debug)]
	pub enum MalformedGenerics {
	/// This link has unbalanced angle brackets.
	///
	/// For example, `Vec<T` should trigger this, as should `Vec<T>>`.
	UnbalancedAngleBrackets,
	/// The generics are not attached to a type.
	///
	/// For example, `<T>` should trigger this.
	///
	/// This is detected by checking if the path is empty after the generics are stripped.
	MissingType,
	/// The link uses fully-qualified syntax, which is currently unsupported.
	///
	/// For example, `<Vec as IntoIterator>::into_iter` should trigger this.
	///
	/// This is detected by checking if ` as ` (the keyword `as` with spaces around it) is inside
	/// angle brackets.
	HasFullyQualifiedSyntax,
	/// The link has an invalid path separator.
	///
	/// For example, `Vec:<T>:new()` should trigger this. Note that `Vec:new()` will not
	/// trigger this because it has no generics and thus [`strip_generics_from_path`] will not be
	/// called.
	///
	/// Note that this will also not be triggered if the invalid path separator is inside angle
	/// brackets because rustdoc mostly ignores what's inside angle brackets (except for
	/// [`HasFullyQualifiedSyntax`](MalformedGenerics::HasFullyQualifiedSyntax)).
	///
	/// This is detected by checking if there is a colon followed by a non-colon in the link.
	InvalidPathSeparator,
	/// The link has too many angle brackets.
	///
	/// For example, `Vec<<T>>` should trigger this.
	TooManyAngleBrackets,
	/// The link has empty angle brackets.
	///
	/// For example, `Vec<>` should trigger this.
	EmptyAngleBrackets,
	}

	/// Removes excess indentation on comments in order for the Markdown
	/// to be parsed correctly. This is necessary because the convention for
	/// writing documentation is to provide a space between the /// or //! marker
	/// and the doc text, but Markdown is whitespace-sensitive. For example,
	/// a block of text with four-space indentation is parsed as a code block,
	/// so if we didn't unindent comments, these list items
	///
	/// /// A list:
	/// ///
	/// /// - Foo
	/// /// - Bar
	///
	/// would be parsed as if they were in a code block, which is likely not what the user intended.
	pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
	// `add` is used in case the most common sugared doc syntax is used ("/// "). The other
	// fragments kind's lines are never starting with a whitespace unless they are using some
	// markdown formatting requiring it. Therefore, if the doc block have a mix between the two,
	// we need to take into account the fact that the minimum indent minus one (to take this
	// whitespace into account).
	//
	// For example:
	//
	// /// hello!
	// #[doc = "another"]
	//
	// In this case, you want "hello! another" and not "hello! another".
	let add = if docs.windows(2).any(\|arr\| arr[0].kind != arr[1].kind)
	&& docs.iter().any(\|d\| d.kind == DocFragmentKind::SugaredDoc)
	{
	// In case we have a mix of sugared doc comments and "raw" ones, we want the sugared one to
	// "decide" how much the minimum indent will be.
	1
	} else {
	0
	};

	// `min_indent` is used to know how much whitespaces from the start of each lines must be
	// removed. Example:
	//
	// /// hello!
	// #[doc = "another"]
	//
	// In here, the `min_indent` is 1 (because non-sugared fragment are always counted with minimum
	// 1 whitespace), meaning that "hello!" will be considered a codeblock because it starts with 4
	// (5 - 1) whitespaces.
	let Some(min_indent) = docs
	.iter()
	.map(\|fragment\| {
	fragment.doc.as_str().lines().fold(usize::MAX, \|min_indent, line\| {
	if line.chars().all(\|c\| c.is_whitespace()) {
	min_indent
	} else {
	// Compare against either space or tab, ignoring whether they are
	// mixed or not.
	let whitespace = line.chars().take_while(\|c\| c == ' ' \|\| c == '\t').count();
	cmp::min(min_indent, whitespace)
	+ if fragment.kind == DocFragmentKind::SugaredDoc { 0 } else { add }
	}
	})
	})
	.min()
	else {
	return;
	};

	for fragment in docs {
	if fragment.doc == kw::Empty {
	continue;
	}

	let min_indent = if fragment.kind != DocFragmentKind::SugaredDoc && min_indent > 0 {
	min_indent - add
	} else {
	min_indent
	};

	fragment.indent = min_indent;
	}
	}

	/// The goal of this function is to apply the `DocFragment` transformation that is required when
	/// transforming into the final Markdown, which is applying the computed indent to each line in
	/// each doc fragment (a `DocFragment` can contain multiple lines in case of `#[doc = ""]`).
	///
	/// Note: remove the trailing newline where appropriate
	pub fn add_doc_fragment(out: &mut String, frag: &DocFragment) {
	let s = frag.doc.as_str();
	let mut iter = s.lines();
	if s.is_empty() {
	out.push('\n');
	return;
	}
	while let Some(line) = iter.next() {
	if line.chars().any(\|c\| !c.is_whitespace()) {
	assert!(line.len() >= frag.indent);
	out.push_str(&line[frag.indent..]);
	} else {
	out.push_str(line);
	}
	out.push('\n');
	}
	}

	pub fn attrs_to_doc_fragments<'a>(
	attrs: impl Iterator<Item = (&'a ast::Attribute, Option<DefId>)>,
	doc_only: bool,
	) -> (Vec<DocFragment>, ast::AttrVec) {
	let mut doc_fragments = Vec::new();
	let mut other_attrs = ast::AttrVec::new();
	for (attr, item_id) in attrs {
	if let Some((doc_str, comment_kind)) = attr.doc_str_and_comment_kind() {
	let doc = beautify_doc_string(doc_str, comment_kind);
	let kind = if attr.is_doc_comment() {
	DocFragmentKind::SugaredDoc
	} else {
	DocFragmentKind::RawDoc
	};
	let fragment = DocFragment { span: attr.span, doc, kind, item_id, indent: 0 };
	doc_fragments.push(fragment);
	} else if !doc_only {
	other_attrs.push(attr.clone());
	}
	}

	unindent_doc_fragments(&mut doc_fragments);

	(doc_fragments, other_attrs)
	}

	/// Return the doc-comments on this item, grouped by the module they came from.
	/// The module can be different if this is a re-export with added documentation.
	///
	/// The last newline is not trimmed so the produced strings are reusable between
	/// early and late doc link resolution regardless of their position.
	pub fn prepare_to_doc_link_resolution(
	doc_fragments: &[DocFragment],
	) -> FxHashMap<Option<DefId>, String> {
	let mut res = FxHashMap::default();
	for fragment in doc_fragments {
	let out_str = res.entry(fragment.item_id).or_default();
	add_doc_fragment(out_str, fragment);
	}
	res
	}

	/// Options for rendering Markdown in the main body of documentation.
	pub fn main_body_opts() -> Options {
	Options::ENABLE_TABLES
	\| Options::ENABLE_FOOTNOTES
	\| Options::ENABLE_STRIKETHROUGH
	\| Options::ENABLE_TASKLISTS
	\| Options::ENABLE_SMART_PUNCTUATION
	}

	fn strip_generics_from_path_segment(segment: Vec<char>) -> Result<String, MalformedGenerics> {
	let mut stripped_segment = String::new();
	let mut param_depth = 0;

	let mut latest_generics_chunk = String::new();

	for c in segment {
	if c == '<' {
	param_depth += 1;
	latest_generics_chunk.clear();
	} else if c == '>' {
	param_depth -= 1;
	if latest_generics_chunk.contains(" as ") {
	// The segment tries to use fully-qualified syntax, which is currently unsupported.
	// Give a helpful error message instead of completely ignoring the angle brackets.
	return Err(MalformedGenerics::HasFullyQualifiedSyntax);
	}
	} else {
	if param_depth == 0 {
	stripped_segment.push(c);
	} else {
	latest_generics_chunk.push(c);
	}
	}
	}

	if param_depth == 0 {
	Ok(stripped_segment)
	} else {
	// The segment has unbalanced angle brackets, e.g. `Vec<T` or `Vec<T>>`
	Err(MalformedGenerics::UnbalancedAngleBrackets)
	}
	}

	pub fn strip_generics_from_path(path_str: &str) -> Result<Box<str>, MalformedGenerics> {
	if !path_str.contains(['<', '>']) {
	return Ok(path_str.into());
	}
	let mut stripped_segments = vec![];
	let mut path = path_str.chars().peekable();
	let mut segment = Vec::new();

	while let Some(chr) = path.next() {
	match chr {
	':' => {
	if path.next_if_eq(&':').is_some() {
	let stripped_segment =
	strip_generics_from_path_segment(mem::take(&mut segment))?;
	if !stripped_segment.is_empty() {
	stripped_segments.push(stripped_segment);
	}
	} else {
	return Err(MalformedGenerics::InvalidPathSeparator);
	}
	}
	'<' => {
	segment.push(chr);

	match path.next() {
	Some('<') => {
	return Err(MalformedGenerics::TooManyAngleBrackets);
	}
	Some('>') => {
	return Err(MalformedGenerics::EmptyAngleBrackets);
	}
	Some(chr) => {
	segment.push(chr);

	while let Some(chr) = path.next_if(\|c\| *c != '>') {
	segment.push(chr);
	}
	}
	None => break,
	}
	}
	_ => segment.push(chr),
	}
	trace!("raw segment: {:?}", segment);
	}

	if !segment.is_empty() {
	let stripped_segment = strip_generics_from_path_segment(segment)?;
	if !stripped_segment.is_empty() {
	stripped_segments.push(stripped_segment);
	}
	}

	debug!("path_str: {:?}\nstripped segments: {:?}", path_str, &stripped_segments);

	let stripped_path = stripped_segments.join("::");

	if !stripped_path.is_empty() {
	Ok(stripped_path.into())
	} else {
	Err(MalformedGenerics::MissingType)
	}
	}

	/// Returns whether the first doc-comment is an inner attribute.
	///
	//// If there are no doc-comments, return true.
	/// FIXME(#78591): Support both inner and outer attributes on the same item.
	pub fn inner_docs(attrs: &[ast::Attribute]) -> bool {
	attrs.iter().find(\|a\| a.doc_str().is_some()).map_or(true, \|a\| a.style == ast::AttrStyle::Inner)
	}

	/// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]`.
	pub fn has_primitive_or_keyword_docs(attrs: &[ast::Attribute]) -> bool {
	for attr in attrs {
	if attr.has_name(sym::rustc_doc_primitive) {
	return true;
	} else if attr.has_name(sym::doc)
	&& let Some(items) = attr.meta_item_list()
	{
	for item in items {
	if item.has_name(sym::keyword) {
	return true;
	}
	}
	}
	}
	false
	}

	/// Simplified version of the corresponding function in rustdoc.
	/// If the rustdoc version returns a successful result, this function must return the same result.
	/// Otherwise this function may return anything.
	fn preprocess_link(link: &str) -> Box<str> {
	let link = link.replace('`', "");
	let link = link.split('#').next().unwrap();
	let link = link.trim();
	let link = link.rsplit('@').next().unwrap();
	let link = link.strip_suffix("()").unwrap_or(link);
	let link = link.strip_suffix("{}").unwrap_or(link);
	let link = link.strip_suffix("[]").unwrap_or(link);
	let link = if link != "!" { link.strip_suffix('!').unwrap_or(link) } else { link };
	let link = link.trim();
	strip_generics_from_path(link).unwrap_or_else(\|_\| link.into())
	}

	/// Keep inline and reference links `[]`,
	/// but skip autolinks `<>` which we never consider to be intra-doc links.
	pub fn may_be_doc_link(link_type: LinkType) -> bool {
	match link_type {
	LinkType::Inline
	\| LinkType::Reference
	\| LinkType::ReferenceUnknown
	\| LinkType::Collapsed
	\| LinkType::CollapsedUnknown
	\| LinkType::Shortcut
	\| LinkType::ShortcutUnknown => true,
	LinkType::Autolink \| LinkType::Email => false,
	}
	}

	/// Simplified version of `preprocessed_markdown_links` from rustdoc.
	/// Must return at least the same links as it, but may add some more links on top of that.
	pub(crate) fn attrs_to_preprocessed_links(attrs: &[ast::Attribute]) -> Vec<Box<str>> {
	let (doc_fragments, _) = attrs_to_doc_fragments(attrs.iter().map(\|attr\| (attr, None)), true);
	let doc = prepare_to_doc_link_resolution(&doc_fragments).into_values().next().unwrap();

	parse_links(&doc)
	}

	/// Similiar version of `markdown_links` from rustdoc.
	/// This will collect destination links and display text if exists.
	fn parse_links<'md>(doc: &'md str) -> Vec<Box<str>> {
	let mut broken_link_callback = \|link: BrokenLink<'md>\| Some((link.reference, "".into()));
	let mut event_iter = Parser::new_with_broken_link_callback(
	&doc,
	main_body_opts(),
	Some(&mut broken_link_callback),
	)
	.into_iter();
	let mut links = Vec::new();

	while let Some(event) = event_iter.next() {
	match event {
	Event::Start(Tag::Link(link_type, dest, _)) if may_be_doc_link(link_type) => {
	if matches!(
	link_type,
	LinkType::Inline
	\| LinkType::ReferenceUnknown
	\| LinkType::Reference
	\| LinkType::Shortcut
	\| LinkType::ShortcutUnknown
	) {
	if let Some(display_text) = collect_link_data(&mut event_iter) {
	links.push(display_text);
	}
	}

	links.push(preprocess_link(&dest));
	}
	_ => {}
	}
	}

	links
	}

	/// Collects additional data of link.
	fn collect_link_data<'input, 'callback>(
	event_iter: &mut Parser<'input, 'callback>,
	) -> Option<Box<str>> {
	let mut display_text: Option<String> = None;
	let mut append_text = \|text: CowStr<'_>\| {
	if let Some(display_text) = &mut display_text {
	display_text.push_str(&text);
	} else {
	display_text = Some(text.to_string());
	}
	};

	while let Some(event) = event_iter.next() {
	match event {
	Event::Text(text) => {
	append_text(text);
	}
	Event::Code(code) => {
	append_text(code);
	}
	Event::End(_) => {
	break;
	}
	_ => {}
	}
	}

	display_text.map(String::into_boxed_str)
	}

	/// Returns a span encompassing all the document fragments.
	pub fn span_of_fragments(fragments: &[DocFragment]) -> Option<Span> {
	if fragments.is_empty() {
	return None;
	}
	let start = fragments[0].span;
	if start == DUMMY_SP {
	return None;
	}
	let end = fragments.last().expect("no doc strings provided").span;
	Some(start.to(end))
	}

	/// Attempts to match a range of bytes from parsed markdown to a `Span` in the source code.
	///
	/// This method will return `None` if we cannot construct a span from the source map or if the
	/// fragments are not all sugared doc comments. It's difficult to calculate the correct span in
	/// that case due to escaping and other source features.
	pub fn source_span_for_markdown_range(
	tcx: TyCtxt<'_>,
	markdown: &str,
	md_range: &Range<usize>,
	fragments: &[DocFragment],
	) -> Option<Span> {
	let is_all_sugared_doc = fragments.iter().all(\|frag\| frag.kind == DocFragmentKind::SugaredDoc);

	if !is_all_sugared_doc {
	return None;
	}

	let snippet = tcx.sess.source_map().span_to_snippet(span_of_fragments(fragments)?).ok()?;

	let starting_line = markdown[..md_range.start].matches('\n').count();
	let ending_line = starting_line + markdown[md_range.start..md_range.end].matches('\n').count();

	// We use `split_terminator('\n')` instead of `lines()` when counting bytes so that we treat
	// CRLF and LF line endings the same way.
	let mut src_lines = snippet.split_terminator('\n');
	let md_lines = markdown.split_terminator('\n');

	// The number of bytes from the source span to the markdown span that are not part
	// of the markdown, like comment markers.
	let mut start_bytes = 0;
	let mut end_bytes = 0;

	'outer: for (line_no, md_line) in md_lines.enumerate() {
	loop {
	let source_line = src_lines.next()?;
	match source_line.find(md_line) {
	Some(offset) => {
	if line_no == starting_line {
	start_bytes += offset;

	if starting_line == ending_line {
	break 'outer;
	}
	} else if line_no == ending_line {
	end_bytes += offset;
	break 'outer;
	} else if line_no < starting_line {
	start_bytes += source_line.len() - md_line.len();
	} else {
	end_bytes += source_line.len() - md_line.len();
	}
	break;
	}
	None => {
	// Since this is a source line that doesn't include a markdown line,
	// we have to count the newline that we split from earlier.
	if line_no <= starting_line {
	start_bytes += source_line.len() + 1;
	} else {
	end_bytes += source_line.len() + 1;
	}
	}
	}
	}
	}

	Some(span_of_fragments(fragments)?.from_inner(InnerSpan::new(
	md_range.start + start_bytes,
	md_range.end + start_bytes + end_bytes,
	)))
	}