Rollup merge of #93072 - m-ou-se:compatible-variants-suggestion-with-desugaring, r=estebank

Compatible variants suggestion with desugaring

This fixes #90553 for `for` loops and other desugarings.

r? ```@estebank```

4 files changed, 74 insertions, 12 deletions

diff --git a/src/test/ui/async-await/proper-span-for-type-error.fixed b/src/test/ui/async-await/proper-span-for-type-error.fixed
index 1f1e1184dcc..7d43b575d2f 100644
--- a/src/test/ui/async-await/proper-span-for-type-error.fixed
+++ b/src/test/ui/async-await/proper-span-for-type-error.fixed
@@ -5,7 +5,8 @@
 async fn a() {}
 
 async fn foo() -> Result<(), i32> {
-    Ok(a().await) //~ ERROR mismatched types
+    a().await;
+    Ok(()) //~ ERROR mismatched types
 }
 
 fn main() {}
diff --git a/src/test/ui/async-await/proper-span-for-type-error.stderr b/src/test/ui/async-await/proper-span-for-type-error.stderr
index 611dc0407bf..25f05156ce2 100644
--- a/src/test/ui/async-await/proper-span-for-type-error.stderr
+++ b/src/test/ui/async-await/proper-span-for-type-error.stderr
@@ -6,10 +6,11 @@ LL |     a().await
    |
    = note:   expected enum `Result<(), i32>`
            found unit type `()`
-help: try wrapping the expression in `Ok`
+help: try adding an expression at the end of the block
+   |
+LL ~     a().await;
+LL ~     Ok(())
    |
-LL |     Ok(a().await)
-   |     +++         +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/compatible-variants.rs b/src/test/ui/did_you_mean/compatible-variants.rs
index a70dda8386f..b078064b267 100644
--- a/src/test/ui/did_you_mean/compatible-variants.rs
+++ b/src/test/ui/did_you_mean/compatible-variants.rs
@@ -23,6 +23,21 @@ fn b() -> Result<(), ()> {
     //~| HELP try adding an expression
 }
 
+fn c() -> Option<()> {
+    for _ in [1, 2] {
+        //~^ ERROR mismatched types
+        f();
+    }
+    //~^ HELP try adding an expression
+}
+
+fn d() -> Option<()> {
+    c()?
+    //~^ ERROR incompatible types
+    //~| HELP try removing this `?`
+    //~| HELP try adding an expression
+}
+
 fn main() {
     let _: Option<()> = while false {};
     //~^ ERROR mismatched types
diff --git a/src/test/ui/did_you_mean/compatible-variants.stderr b/src/test/ui/did_you_mean/compatible-variants.stderr
index 0dfd8f5c128..51c1bf97c4e 100644
--- a/src/test/ui/did_you_mean/compatible-variants.stderr
+++ b/src/test/ui/did_you_mean/compatible-variants.stderr
@@ -37,7 +37,52 @@ LL +     Ok(())
    |
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:27:25
+  --> $DIR/compatible-variants.rs:27:5
+   |
+LL |   fn c() -> Option<()> {
+   |             ---------- expected `Option<()>` because of return type
+LL | /     for _ in [1, 2] {
+LL | |
+LL | |         f();
+LL | |     }
+   | |_____^ expected enum `Option`, found `()`
+   |
+   = note:   expected enum `Option<()>`
+           found unit type `()`
+help: try adding an expression at the end of the block
+   |
+LL ~     }
+LL +     None
+   |
+LL ~     }
+LL +     Some(())
+   |
+
+error[E0308]: `?` operator has incompatible types
+  --> $DIR/compatible-variants.rs:35:5
+   |
+LL |     c()?
+   |     ^^^^ expected enum `Option`, found `()`
+   |
+   = note: `?` operator cannot convert from `()` to `Option<()>`
+   = note:   expected enum `Option<()>`
+           found unit type `()`
+help: try removing this `?`
+   |
+LL -     c()?
+LL +     c()
+   | 
+help: try adding an expression at the end of the block
+   |
+LL ~     c()?;
+LL +     None
+   |
+LL ~     c()?;
+LL +     Some(())
+   |
+
+error[E0308]: mismatched types
+  --> $DIR/compatible-variants.rs:42:25
    |
 LL |     let _: Option<()> = while false {};
    |            ----------   ^^^^^^^^^^^^^^ expected enum `Option`, found `()`
@@ -52,7 +97,7 @@ LL |     let _: Option<()> = Some(while false {});
    |                         +++++              +
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:31:9
+  --> $DIR/compatible-variants.rs:46:9
    |
 LL |         while false {}
    |         ^^^^^^^^^^^^^^ expected enum `Option`, found `()`
@@ -69,7 +114,7 @@ LL +         Some(())
    |
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:35:31
+  --> $DIR/compatible-variants.rs:50:31
    |
 LL |     let _: Result<i32, i32> = 1;
    |            ----------------   ^ expected enum `Result`, found integer
@@ -86,7 +131,7 @@ LL |     let _: Result<i32, i32> = Err(1);
    |                               ++++ +
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:38:26
+  --> $DIR/compatible-variants.rs:53:26
    |
 LL |     let _: Option<i32> = 1;
    |            -----------   ^ expected enum `Option`, found integer
@@ -101,7 +146,7 @@ LL |     let _: Option<i32> = Some(1);
    |                          +++++ +
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:41:28
+  --> $DIR/compatible-variants.rs:56:28
    |
 LL |     let _: Hey<i32, i32> = 1;
    |            -------------   ^ expected enum `Hey`, found integer
@@ -118,7 +163,7 @@ LL |     let _: Hey<i32, i32> = Hey::B(1);
    |                            +++++++ +
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:44:29
+  --> $DIR/compatible-variants.rs:59:29
    |
 LL |     let _: Hey<i32, bool> = false;
    |            --------------   ^^^^^ expected enum `Hey`, found `bool`
@@ -133,7 +178,7 @@ LL |     let _: Hey<i32, bool> = Hey::B(false);
    |                             +++++++     +
 
 error[E0308]: mismatched types
-  --> $DIR/compatible-variants.rs:48:19
+  --> $DIR/compatible-variants.rs:63:19
    |
 LL |     let _ = Foo { bar };
    |                   ^^^ expected enum `Option`, found `i32`
@@ -145,6 +190,6 @@ help: try wrapping the expression in `Some`
 LL |     let _ = Foo { bar: Some(bar) };
    |                   ++++++++++   +
 
-error: aborting due to 9 previous errors
+error: aborting due to 11 previous errors
 
 For more information about this error, try `rustc --explain E0308`.