Auto merge of #6337 - ThibsG:FixIce6332, r=Manishearth

Remove `expect()` calls to avoid ICEs in `deref_addrof` lint

Fixes: #6332

changelog: none

clippy_lints/src/reference.rs

@@ -60,33 +60,41 @@ impl EarlyLintPass for DerefAddrOf {
                             }).map_or(span, |start_no_whitespace| e.span.with_lo(start_no_whitespace))
                         };
 
-                        let rpos = if *mutability == Mutability::Mut {
+                        let mut generate_snippet = |pattern: &str| {
-                            macro_source.rfind("mut").expect("already checked this is a mutable reference") + "mut".len()
-                        } else {
-                            macro_source.rfind('&').expect("already checked this is a reference") + "&".len()
-                        };
                             #[allow(clippy::cast_possible_truncation)]
+                            macro_source.rfind(pattern).map(|pattern_pos| {
+                                let rpos = pattern_pos + pattern.len();
                                 let span_after_ref = e.span.with_lo(BytePos(e.span.lo().0 + rpos as u32));
                                 let span = trim_leading_whitespaces(span_after_ref);
                                 snippet_with_applicability(cx, span, "_", &mut applicability)
+                            })
+                        };
+
+                        if *mutability == Mutability::Mut {
+                            generate_snippet("mut")
                         } else {
-                        snippet_with_applicability(cx, e.span, "_", &mut applicability)
+                            generate_snippet("&")
                         }
                     } else {
-                    snippet_with_applicability(cx, addrof_target.span, "_", &mut applicability)
+                        Some(snippet_with_applicability(cx, e.span, "_", &mut applicability))
-                }.to_string();
+                    }
+                } else {
+                    Some(snippet_with_applicability(cx, addrof_target.span, "_", &mut applicability))
+                };
+                if let Some(sugg) = sugg {
                     span_lint_and_sugg(
                         cx,
                         DEREF_ADDROF,
                         e.span,
                         "immediately dereferencing a reference",
                         "try this",
-                    sugg,
+                        sugg.to_string(),
                         applicability,
                     );
                 }
             }
         }
+    }
 }
 
 declare_clippy_lint! {

tests/ui/crashes/ice-6332.rs

@@ -0,0 +1,11 @@
+fn cmark_check() {
+    let mut link_err = false;
+    macro_rules! cmark_error {
+        ($bad:expr) => {
+            *$bad = true;
+        };
+    }
+    cmark_error!(&mut link_err);
+}
+
+pub fn main() {}