rustdoc: Unindent doc fragments on Attributes construction

src/librustdoc/clean/types.rs

@@ -1,13 +1,11 @@
 use std::cell::RefCell;
 use std::default::Default;
-use std::fmt;
 use std::hash::Hash;
-use std::iter;
 use std::lazy::SyncOnceCell as OnceCell;
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
-use std::vec;
+use std::{cmp, fmt, iter};
 
 use arrayvec::ArrayVec;
 
@@ -55,6 +53,9 @@ crate use self::Type::{
 };
 crate use self::Visibility::{Inherited, Public};
 
+#[cfg(test)]
+mod tests;
+
 crate type ItemIdSet = FxHashSet<ItemId>;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Copy)]
@@ -1028,6 +1029,86 @@ crate fn collapse_doc_fragments(doc_strings: &[DocFragment]) -> String {
     acc
 }
 
+/// 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.
+fn unindent_doc_fragments(docs: &mut Vec<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;
+    }
+}
+
 /// A link that has not yet been rendered.
 ///
 /// This link will be turned into a rendered link by [`Item::links`].
@@ -1119,6 +1200,8 @@ impl Attributes {
             }
         }
 
+        unindent_doc_fragments(&mut doc_strings);
+
         Attributes { doc_strings, other_attrs }
     }
 

src/librustdoc/passes/unindent_comments/tests.rs → src/librustdoc/clean/types/tests.rs

@@ -20,7 +20,7 @@ fn create_doc_fragment(s: &str) -> Vec<DocFragment> {
 fn run_test(input: &str, expected: &str) {
     create_default_session_globals_then(|| {
         let mut s = create_doc_fragment(input);
-        unindent_fragments(&mut s);
+        unindent_doc_fragments(&mut s);
         assert_eq!(collapse_doc_fragments(&s), expected);
     });
 }

src/librustdoc/doctest.rs

@@ -1174,8 +1174,6 @@ impl<'a, 'hir, 'tcx> HirCollector<'a, 'hir, 'tcx> {
         nested: F,
     ) {
         let ast_attrs = self.tcx.hir().attrs(hir_id);
-        let mut attrs = Attributes::from_ast(ast_attrs, None);
-
         if let Some(ref cfg) = ast_attrs.cfg(self.tcx, &FxHashSet::default()) {
             if !cfg.matches(&self.sess.parse_sess, Some(self.sess.features_untracked())) {
                 return;
@@ -1187,9 +1185,9 @@ impl<'a, 'hir, 'tcx> HirCollector<'a, 'hir, 'tcx> {
             self.collector.names.push(name);
         }
 
-        attrs.unindent_doc_comments();
         // The collapse-docs pass won't combine sugared/raw doc attributes, or included files with
         // anything else, this will combine them for us.
+        let attrs = Attributes::from_ast(ast_attrs, None);
         if let Some(doc) = attrs.collapsed_doc_value() {
             // Use the outermost invocation, so that doctest names come from where the docs were written.
             let span = ast_attrs

src/librustdoc/passes/collect_intra_doc_links/early.rs

@@ -63,9 +63,7 @@ crate fn early_resolve_intra_doc_links(
 }
 
 fn doc_attrs<'a>(attrs: impl Iterator<Item = &'a ast::Attribute>) -> Attributes {
-    let mut attrs = Attributes::from_ast_iter(attrs.map(|attr| (attr, None)), true);
-    attrs.unindent_doc_comments();
-    attrs
+    Attributes::from_ast_iter(attrs.map(|attr| (attr, None)), true)
 }
 
 struct EarlyDocLinkResolver<'r, 'ra> {

src/librustdoc/passes/mod.rs

@@ -24,9 +24,6 @@ crate use self::strip_private::STRIP_PRIVATE;
 mod strip_priv_imports;
 crate use self::strip_priv_imports::STRIP_PRIV_IMPORTS;
 
-mod unindent_comments;
-crate use self::unindent_comments::UNINDENT_COMMENTS;
-
 mod propagate_doc_cfg;
 crate use self::propagate_doc_cfg::PROPAGATE_DOC_CFG;
 
@@ -81,7 +78,6 @@ crate enum Condition {
 crate const PASSES: &[Pass] = &[
     CHECK_DOC_TEST_VISIBILITY,
     STRIP_HIDDEN,
-    UNINDENT_COMMENTS,
     STRIP_PRIVATE,
     STRIP_PRIV_IMPORTS,
     PROPAGATE_DOC_CFG,
@@ -96,7 +92,6 @@ crate const PASSES: &[Pass] = &[
 /// The list of passes run by default.
 crate const DEFAULT_PASSES: &[ConditionalPass] = &[
     ConditionalPass::always(COLLECT_TRAIT_IMPLS),
-    ConditionalPass::always(UNINDENT_COMMENTS),
     ConditionalPass::always(CHECK_DOC_TEST_VISIBILITY),
     ConditionalPass::new(STRIP_HIDDEN, WhenNotDocumentHidden),
     ConditionalPass::new(STRIP_PRIVATE, WhenNotDocumentPrivate),

src/test/rustdoc-ui/issue-91713.stdout

@@ -1,7 +1,6 @@
 Available passes for running rustdoc:
 check_doc_test_visibility - run various visibility-related lints on doctests
         strip-hidden - strips all `#[doc(hidden)]` items from the output
-   unindent-comments - removes excess indentation on comments in order for markdown to like it
        strip-private - strips all private items from a crate which cannot be seen externally, implies strip-priv-imports
   strip-priv-imports - strips all private import statements (`use`, `extern crate`) from a crate
    propagate-doc-cfg - propagates `#[doc(cfg(...))]` to child items
@@ -14,7 +13,6 @@ check-invalid-html-tags - detects invalid HTML tags in doc comments
 
 Default passes for rustdoc:
  collect-trait-impls
-   unindent-comments
 check_doc_test_visibility
         strip-hidden  (when not --document-hidden-items)
        strip-private  (when not --document-private-items)