Rollup merge of rust-lang#44329 - nrc:pulldown-warn-fix, r=ollie27

Fixup some nits from rust-lang#44238

r? @ollie27

Author: frewsxcv

src/librustdoc/html/render.rs

@@ -606,12 +606,20 @@ pub fn run(mut krate: clean::Crate,
 }
 
 // A short, single-line view of `s`.
-fn concise_str(s: &str) -> String {
+fn concise_str(mut s: &str) -> String {
     if s.contains('\n') {
-        return format!("{}...", s.lines().next().expect("Impossible! We just found a newline"));
+        s = s.lines().next().expect("Impossible! We just found a newline");
     }
     if s.len() > 70 {
-        return format!("{} ... {}", &s[..50], &s[s.len()-20..]);
+        let mut lo = 50;
+        let mut hi = s.len() - 20;
+        while !s.is_char_boundary(lo) {
+            lo -= 1;
+        }
+        while !s.is_char_boundary(hi) {
+            hi += 1;
+        }
+        return format!("{} ... {}", &s[..lo], &s[hi..]);
     }
     s.to_owned()
 }
@@ -1756,18 +1764,18 @@ fn render_markdown(w: &mut fmt::Formatter,
     // We only emit warnings if the user has opted-in to Pulldown rendering.
     let output = if render_type == RenderType::Pulldown {
         let pulldown_output = format!("{}", Markdown(md_text, RenderType::Pulldown));
-        let differences = html_diff::get_differences(&pulldown_output, &hoedown_output);
-        let differences = differences.into_iter()
-            .filter(|s| {
-                match *s {
-                    html_diff::Difference::NodeText { ref elem_text,
-                                                      ref opposite_elem_text,
-                                                      .. }
-                        if match_non_whitespace(elem_text, opposite_elem_text) => false,
-                    _ => true,
+        let mut differences = html_diff::get_differences(&pulldown_output, &hoedown_output);
+        differences.retain(|s| {
+            match *s {
+                html_diff::Difference::NodeText { ref elem_text,
+                                                  ref opposite_elem_text,
+                                                  .. }
+                    if elem_text.split_whitespace().eq(opposite_elem_text.split_whitespace()) => {
+                        false
                 }
-            })
-            .collect::<Vec<_>>();
+                _ => true,
+            }
+        });
 
         if !differences.is_empty() {
             scx.markdown_warnings.borrow_mut().push((span, md_text.to_owned(), differences));
@@ -1781,40 +1789,6 @@ fn render_markdown(w: &mut fmt::Formatter,
     write!(w, "<div class='docblock'>{}{}</div>", prefix, output)
 }
 
-// Returns true iff s1 and s2 match, ignoring whitespace.
-fn match_non_whitespace(s1: &str, s2: &str) -> bool {
-    let s1 = s1.trim();
-    let s2 = s2.trim();
-    let mut cs1 = s1.chars();
-    let mut cs2 = s2.chars();
-    while let Some(c1) = cs1.next() {
-        if c1.is_whitespace() {
-            continue;
-        }
-
-        loop {
-            if let Some(c2) = cs2.next() {
-                if !c2.is_whitespace() {
-                    if c1 != c2 {
-                        return false;
-                    }
-                    break;
-                }
-            } else {
-                return false;
-            }
-        }
-    }
-
-    while let Some(c2) = cs2.next() {
-        if !c2.is_whitespace() {
-            return false;
-        }
-    }
-
-    true
-}
-
 fn document_short(w: &mut fmt::Formatter, item: &clean::Item, link: AssocItemLink,
                   cx: &Context, prefix: &str) -> fmt::Result {
     if let Some(s) = item.doc_value() {
@@ -3791,35 +3765,3 @@ fn test_name_sorting() {
     sorted.sort_by_key(|&s| name_key(s));
     assert_eq!(names, sorted);
 }
-
-#[cfg(test)]
-#[test]
-fn test_match_non_whitespace() {
-    assert!(match_non_whitespace("", ""));
-    assert!(match_non_whitespace("  ", ""));
-    assert!(match_non_whitespace("", "  "));
-
-    assert!(match_non_whitespace("a", "a"));
-    assert!(match_non_whitespace(" a ", "a"));
-    assert!(match_non_whitespace("a", "  a"));
-    assert!(match_non_whitespace("abc", "abc"));
-    assert!(match_non_whitespace("abc", " abc "));
-    assert!(match_non_whitespace("abc  ", "abc"));
-    assert!(match_non_whitespace("abc xyz", "abc xyz"));
-    assert!(match_non_whitespace("abc xyz", "abc\nxyz"));
-    assert!(match_non_whitespace("abc xyz", "abcxyz"));
-    assert!(match_non_whitespace("abcxyz", "abc xyz"));
-    assert!(match_non_whitespace("abc    xyz ", " abc xyz\n"));
-
-    assert!(!match_non_whitespace("a", "b"));
-    assert!(!match_non_whitespace(" a ", "c"));
-    assert!(!match_non_whitespace("a", "  aa"));
-    assert!(!match_non_whitespace("abc", "ac"));
-    assert!(!match_non_whitespace("abc", " adc "));
-    assert!(!match_non_whitespace("abc  ", "abca"));
-    assert!(!match_non_whitespace("abc xyz", "abc xy"));
-    assert!(!match_non_whitespace("abc xyz", "bc\nxyz"));
-    assert!(!match_non_whitespace("abc xyz", "abc.xyz"));
-    assert!(!match_non_whitespace("abcxyz", "abc.xyz"));
-    assert!(!match_non_whitespace("abc    xyz ", " abc xyz w"));
-}