remove redundent "<>" for ty::Slice with reference type

this fix #103271

1 files changed, 44 insertions, 0 deletions

diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index f9566eeee94..029cd93a52a 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -753,6 +753,50 @@ impl SourceMap {
         }
     }
 
+    /// Given a 'Span', tries to tell if the next character is '>'
+    /// and the previous charactoer is '<' after skipping white space
+    /// return true if wrapped by '<>'
+    pub fn span_wrapped_by_angle_bracket(&self, span: Span) -> bool {
+        self.span_to_source(span, |src, start_index, end_index| {
+            if src.get(start_index..end_index).is_none() {
+                return Ok(false);
+            }
+            // test the right side to match '>' after skipping white space
+            let end_src = &src[end_index..];
+            let mut i = 0;
+            while let Some(cc) = end_src.chars().nth(i) {
+                if cc == ' ' {
+                    i = i + 1;
+                } else if cc == '>' {
+                    // found > in the right;
+                    break;
+                } else {
+                    // failed to find '>' return false immediately
+                    return Ok(false);
+                }
+            }
+            // test the left side to match '<' after skipping white space
+            i = start_index;
+            let start_src = &src[0..start_index];
+            while let Some(cc) = start_src.chars().nth(i) {
+                if cc == ' ' {
+                    if i == 0 {
+                        return Ok(false);
+                    }
+                    i = i - 1;
+                } else if cc == '<' {
+                    // found < in the left
+                    break;
+                } else {
+                    // failed to find '<' return false immediately
+                    return Ok(false);
+                }
+            }
+            return Ok(true);
+        })
+        .map_or(false, |is_accessible| is_accessible)
+    }
+
     /// Given a `Span`, tries to get a shorter span ending just after the first occurrence of `char`
     /// `c`.
     pub fn span_through_char(&self, sp: Span, c: char) -> Span {