Auto merge of #95119 - OliverMD:method_suggestions, r=davidtwco

Improve method name suggestions

Attempts to improve method name suggestions when a matching method name
is not found. The approach taken is use the Levenshtein distance and
account for substrings having a high distance but can sometimes be very
close to the intended method (eg. empty vs is_empty).

resolves #94747

6 files changed, 12 insertions, 5 deletions

diff --git a/src/test/ui/associated-item/associated-item-enum.stderr b/src/test/ui/associated-item/associated-item-enum.stderr
index cadf55454a7..d52b2b36c7b 100644
--- a/src/test/ui/associated-item/associated-item-enum.stderr
+++ b/src/test/ui/associated-item/associated-item-enum.stderr
@@ -17,7 +17,10 @@ LL | enum Enum { Variant }
    | --------- variant or associated item `mispellable_trait` not found here
 ...
 LL |     Enum::mispellable_trait();
-   |           ^^^^^^^^^^^^^^^^^ variant or associated item not found in `Enum`
+   |           ^^^^^^^^^^^^^^^^^
+   |           |
+   |           variant or associated item not found in `Enum`
+   |           help: there is an associated function with a similar name: `misspellable`
 
 error[E0599]: no variant or associated item named `MISPELLABLE` found for enum `Enum` in the current scope
   --> $DIR/associated-item-enum.rs:19:11
diff --git a/src/test/ui/derives/issue-91550.stderr b/src/test/ui/derives/issue-91550.stderr
index bf4b7c7da0d..1b26d754984 100644
--- a/src/test/ui/derives/issue-91550.stderr
+++ b/src/test/ui/derives/issue-91550.stderr
@@ -8,7 +8,7 @@ LL | struct Value(u32);
    | doesn't satisfy `Value: Hash`
 ...
 LL |     hs.insert(Value(0));
-   |        ^^^^^^ method cannot be called on `HashSet<Value>` due to unsatisfied trait bounds
+   |        ^^^^^^
    |
    = note: the following trait bounds were not satisfied:
            `Value: Eq`
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr
index 52ee1db5b15..943f7748696 100644
--- a/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr
+++ b/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr
@@ -2,7 +2,7 @@ error[E0599]: the method `as_deref_mut` exists for enum `Option<{integer}>`, but
   --> $DIR/option-as_deref_mut.rs:2:33
    |
 LL |     let _result = &mut Some(42).as_deref_mut();
-   |                                 ^^^^^^^^^^^^ method cannot be called on `Option<{integer}>` due to unsatisfied trait bounds
+   |                                 ^^^^^^^^^^^^
    |
    = note: the following trait bounds were not satisfied:
            `{integer}: Deref`
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr
index 018557881ef..aa771e4c04e 100644
--- a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr
+++ b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr
@@ -2,7 +2,7 @@ error[E0599]: the method `as_deref_mut` exists for enum `Result<{integer}, _>`,
   --> $DIR/result-as_deref_mut.rs:2:31
    |
 LL |     let _result = &mut Ok(42).as_deref_mut();
-   |                               ^^^^^^^^^^^^ method cannot be called on `Result<{integer}, _>` due to unsatisfied trait bounds
+   |                               ^^^^^^^^^^^^
    |
    = note: the following trait bounds were not satisfied:
            `{integer}: Deref`
diff --git a/src/test/ui/rust-2018/trait-import-suggestions.stderr b/src/test/ui/rust-2018/trait-import-suggestions.stderr
index eb4e43aaec3..6454b6045e4 100644
--- a/src/test/ui/rust-2018/trait-import-suggestions.stderr
+++ b/src/test/ui/rust-2018/trait-import-suggestions.stderr
@@ -45,6 +45,10 @@ help: the following trait is implemented but not in scope; perhaps add a `use` f
    |
 LL | use std::str::FromStr;
    |
+help: there is an associated function with a similar name
+   |
+LL |     let y = u32::from_str_radix("33");
+   |                  ~~~~~~~~~~~~~~
 
 error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/suggestions/suggest-methods.stderr b/src/test/ui/suggestions/suggest-methods.stderr
index 535841e535b..9079e8f2ce7 100644
--- a/src/test/ui/suggestions/suggest-methods.stderr
+++ b/src/test/ui/suggestions/suggest-methods.stderr
@@ -23,7 +23,7 @@ error[E0599]: no method named `count_o` found for type `u32` in the current scop
   --> $DIR/suggest-methods.rs:28:19
    |
 LL |     let _ = 63u32.count_o();
-   |                   ^^^^^^^ method not found in `u32`
+   |                   ^^^^^^^ help: there is an associated function with a similar name: `count_ones`
 
 error: aborting due to 4 previous errors