From a860a720baa508aa28d44f4d277814a086d6bd9d Mon Sep 17 00:00:00 2001
From: yukang <moorekang@gmail.com>
Date: Mon, 20 Mar 2023 22:48:26 +0800
Subject: [PATCH] Fix issue when there are multiple candidates for
 edit_distance_with_substrings

---
 compiler/rustc_span/src/edit_distance.rs | 24 ++++++++++++++++++++----
 tests/ui/suggestions/issue-109291.rs     |  4 ++++
 tests/ui/suggestions/issue-109291.stderr | 12 ++++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)
 create mode 100644 tests/ui/suggestions/issue-109291.rs
 create mode 100644 tests/ui/suggestions/issue-109291.stderr

diff --git a/compiler/rustc_span/src/edit_distance.rs b/compiler/rustc_span/src/edit_distance.rs
index 89f0386e3e9..40d36578350 100644
--- a/compiler/rustc_span/src/edit_distance.rs
+++ b/compiler/rustc_span/src/edit_distance.rs
@@ -174,10 +174,10 @@ pub fn find_best_match_for_name(
 fn find_best_match_for_name_impl(
     use_substring_score: bool,
     candidates: &[Symbol],
-    lookup: Symbol,
+    lookup_symbol: Symbol,
     dist: Option<usize>,
 ) -> Option<Symbol> {
-    let lookup = lookup.as_str();
+    let lookup = lookup_symbol.as_str();
     let lookup_uppercase = lookup.to_uppercase();
 
     // Priority of matches:
@@ -190,6 +190,7 @@ fn find_best_match_for_name_impl(
 
     let mut dist = dist.unwrap_or_else(|| cmp::max(lookup.len(), 3) / 3);
     let mut best = None;
+    let mut next_candidates = vec![];
     for c in candidates {
         match if use_substring_score {
             edit_distance_with_substrings(lookup, c.as_str(), dist)
@@ -198,12 +199,27 @@ fn find_best_match_for_name_impl(
         } {
             Some(0) => return Some(*c),
             Some(d) => {
-                dist = d - 1;
-                best = Some(*c);
+                if use_substring_score {
+                    dist = d;
+                    next_candidates.push(*c);
+                    best = Some(*c);
+                } else {
+                    dist = d - 1;
+                    best = Some(*c);
+                }
             }
             None => {}
         }
     }
+
+    if next_candidates.len() > 1 {
+        best = find_best_match_for_name_impl(
+            false,
+            &next_candidates,
+            lookup_symbol,
+            Some(lookup.len()),
+        );
+    }
     if best.is_some() {
         return best;
     }
diff --git a/tests/ui/suggestions/issue-109291.rs b/tests/ui/suggestions/issue-109291.rs
new file mode 100644
index 00000000000..1947b16a32e
--- /dev/null
+++ b/tests/ui/suggestions/issue-109291.rs
@@ -0,0 +1,4 @@
+fn main() {
+    println!("Custom backtrace: {}", std::backtrace::Backtrace::forced_capture());
+    //~^ ERROR no function or associated item name
+}
diff --git a/tests/ui/suggestions/issue-109291.stderr b/tests/ui/suggestions/issue-109291.stderr
new file mode 100644
index 00000000000..4ef5948d9bf
--- /dev/null
+++ b/tests/ui/suggestions/issue-109291.stderr
@@ -0,0 +1,12 @@
+error[E0599]: no function or associated item named `forced_capture` found for struct `Backtrace` in the current scope
+  --> $DIR/issue-109291.rs:2:65
+   |
+LL |     println!("Custom backtrace: {}", std::backtrace::Backtrace::forced_capture());
+   |                                                                 ^^^^^^^^^^^^^^
+   |                                                                 |
+   |                                                                 function or associated item not found in `Backtrace`
+   |                                                                 help: there is an associated function with a similar name: `force_capture`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.