Rollup merge of #94739 - estebank:suggest-let-else, r=oli-obk

Suggest `if let`/`let_else` for refutable pat in `let`

r? `````@oli-obk`````

3 files changed, 24 insertions, 16 deletions

diff --git a/src/test/ui/pattern/usefulness/issue-31561.stderr b/src/test/ui/pattern/usefulness/issue-31561.stderr
index dffcfc01607..9da6b5eeead 100644
--- a/src/test/ui/pattern/usefulness/issue-31561.stderr
+++ b/src/test/ui/pattern/usefulness/issue-31561.stderr
@@ -17,10 +17,14 @@ LL |     Bar,
 LL |     Baz
    |     ^^^ not covered
    = note: the matched value is of type `Thing`
-help: you might want to use `if let` to ignore the variant that isn't matched
+help: you might want to use `if let` to ignore the variants that aren't matched
    |
-LL |     if let Thing::Foo(y) = Thing::Foo(1) { /* */ }
+LL |     let y = if let Thing::Foo(y) = Thing::Foo(1) { y } else { todo!() };
+   |     ++++++++++                                   ++++++++++++++++++++++
+help: alternatively, on nightly, you might want to use `#![feature(let_else)]` to handle the variants that aren't matched
    |
+LL |     let Thing::Foo(y) = Thing::Foo(1) else { todo!() };
+   |                                       ++++++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/pattern/usefulness/non-exhaustive-defined-here.stderr b/src/test/ui/pattern/usefulness/non-exhaustive-defined-here.stderr
index 8f5adccea80..0f06c31c468 100644
--- a/src/test/ui/pattern/usefulness/non-exhaustive-defined-here.stderr
+++ b/src/test/ui/pattern/usefulness/non-exhaustive-defined-here.stderr
@@ -42,10 +42,10 @@ LL |     B,
 LL |     C
    |     ^ not covered
    = note: the matched value is of type `E`
-help: you might want to use `if let` to ignore the variant that isn't matched
+help: you might want to use `if let` to ignore the variants that aren't matched
    |
-LL |     if let E::A = e { /* */ }
-   |     ~~~~~~~~~~~~~~~~~~~~~~~~~
+LL |     if let E::A = e { todo!() }
+   |     ++              ~~~~~~~~~~~
 
 error[E0004]: non-exhaustive patterns: `&B` and `&C` not covered
   --> $DIR/non-exhaustive-defined-here.rs:52:11
@@ -91,10 +91,10 @@ LL |     B,
 LL |     C
    |     ^ not covered
    = note: the matched value is of type `&E`
-help: you might want to use `if let` to ignore the variant that isn't matched
+help: you might want to use `if let` to ignore the variants that aren't matched
    |
-LL |     if let E::A = e { /* */ }
-   |     ~~~~~~~~~~~~~~~~~~~~~~~~~
+LL |     if let E::A = e { todo!() }
+   |     ++              ~~~~~~~~~~~
 
 error[E0004]: non-exhaustive patterns: `&&mut &B` and `&&mut &C` not covered
   --> $DIR/non-exhaustive-defined-here.rs:66:11
@@ -140,10 +140,10 @@ LL |     B,
 LL |     C
    |     ^ not covered
    = note: the matched value is of type `&&mut &E`
-help: you might want to use `if let` to ignore the variant that isn't matched
-   |
-LL |     if let E::A = e { /* */ }
+help: you might want to use `if let` to ignore the variants that aren't matched
    |
+LL |     if let E::A = e { todo!() }
+   |     ++              ~~~~~~~~~~~
 
 error[E0004]: non-exhaustive patterns: `None` not covered
   --> $DIR/non-exhaustive-defined-here.rs:92:11
@@ -185,8 +185,12 @@ LL |     None,
    = note: the matched value is of type `Opt`
 help: you might want to use `if let` to ignore the variant that isn't matched
    |
-LL |     if let Opt::Some(ref _x) = e { /* */ }
-   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+LL |     let _x = if let Opt::Some(ref _x) = e { _x } else { todo!() };
+   |     +++++++++++                           +++++++++++++++++++++++
+help: alternatively, on nightly, you might want to use `#![feature(let_else)]` to handle the variant that isn't matched
+   |
+LL |     let Opt::Some(ref _x) = e else { todo!() };
+   |                               ++++++++++++++++
 
 error: aborting due to 8 previous errors
 
diff --git a/src/test/ui/pattern/usefulness/refutable-pattern-errors.stderr b/src/test/ui/pattern/usefulness/refutable-pattern-errors.stderr
index 74ec646e31c..d1dacc822e9 100644
--- a/src/test/ui/pattern/usefulness/refutable-pattern-errors.stderr
+++ b/src/test/ui/pattern/usefulness/refutable-pattern-errors.stderr
@@ -15,10 +15,10 @@ LL |     let (1, (Some(1), 2..=3)) = (1, (None, 2));
    = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
    = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
    = note: the matched value is of type `(i32, (Option<i32>, i32))`
-help: you might want to use `if let` to ignore the variant that isn't matched
-   |
-LL |     if let (1, (Some(1), 2..=3)) = (1, (None, 2)) { /* */ }
+help: you might want to use `if let` to ignore the variants that aren't matched
    |
+LL |     if let (1, (Some(1), 2..=3)) = (1, (None, 2)) { todo!() }
+   |     ++                                            ~~~~~~~~~~~
 
 error: aborting due to 2 previous errors