Rollup merge of #64049 - estebank:if-else-type-err, r=Centril

Emit a single error on if expr with expectation and no else clause

Fix https://github.com/rust-lang/rust/issues/60254.

r? @Centril

src/test/ui/if/if-without-else-as-fn-expr.rs

@@ -3,7 +3,6 @@ fn foo(bar: usize) -> usize {
         return 3;
     }
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
 }
 
 fn foo2(bar: usize) -> usize {
@@ -11,7 +10,6 @@ fn foo2(bar: usize) -> usize {
         return 3;
     };
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
     x
 }
 
@@ -20,7 +18,6 @@ fn foo3(bar: usize) -> usize {
         3
     }
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
 }
 
 fn foo_let(bar: usize) -> usize {
@@ -28,7 +25,6 @@ fn foo_let(bar: usize) -> usize {
         return 3;
     }
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
 }
 
 fn foo2_let(bar: usize) -> usize {
@@ -36,7 +32,6 @@ fn foo2_let(bar: usize) -> usize {
         return 3;
     };
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
     x
 }
 
@@ -45,7 +40,6 @@ fn foo3_let(bar: usize) -> usize {
         3
     }
     //~^^^ ERROR if may be missing an else clause
-    //~| ERROR mismatched types [E0308]
 }
 
 // FIXME(60254): deduplicate first error in favor of second.

src/test/ui/if/if-without-else-as-fn-expr.stderr

@@ -1,14 +1,3 @@
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:2:5
-   |
-LL | /     if bar % 5 == 0 {
-LL | |         return 3;
-LL | |     }
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
   --> $DIR/if-without-else-as-fn-expr.rs:2:5
    |
@@ -24,20 +13,8 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:10:20
-   |
-LL |       let x: usize = if bar % 5 == 0 {
-   |  ____________________^
-LL | |         return 3;
-LL | |     };
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
-  --> $DIR/if-without-else-as-fn-expr.rs:10:20
+  --> $DIR/if-without-else-as-fn-expr.rs:9:20
    |
 LL |       let x: usize = if bar % 5 == 0 {
    |  _________-__________^
@@ -52,19 +29,8 @@ LL | |     };
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:19:5
-   |
-LL | /     if bar % 5 == 0 {
-LL | |         3
-LL | |     }
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
-  --> $DIR/if-without-else-as-fn-expr.rs:19:5
+  --> $DIR/if-without-else-as-fn-expr.rs:17:5
    |
 LL |   fn foo3(bar: usize) -> usize {
    |                          ----- expected `usize` because of this return type
@@ -78,19 +44,8 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:27:5
-   |
-LL | /     if let 0 = 1 {
-LL | |         return 3;
-LL | |     }
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
-  --> $DIR/if-without-else-as-fn-expr.rs:27:5
+  --> $DIR/if-without-else-as-fn-expr.rs:24:5
    |
 LL |   fn foo_let(bar: usize) -> usize {
    |                             ----- expected `usize` because of this return type
@@ -104,20 +59,8 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:35:20
-   |
-LL |       let x: usize = if let 0 = 1 {
-   |  ____________________^
-LL | |         return 3;
-LL | |     };
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
-  --> $DIR/if-without-else-as-fn-expr.rs:35:20
+  --> $DIR/if-without-else-as-fn-expr.rs:31:20
    |
 LL |       let x: usize = if let 0 = 1 {
    |  _________-__________^
@@ -132,19 +75,8 @@ LL | |     };
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error[E0308]: mismatched types
-  --> $DIR/if-without-else-as-fn-expr.rs:44:5
-   |
-LL | /     if let 0 = 1 {
-LL | |         3
-LL | |     }
-   | |_____^ expected usize, found ()
-   |
-   = note: expected type `usize`
-              found type `()`
-
 error[E0317]: if may be missing an else clause
-  --> $DIR/if-without-else-as-fn-expr.rs:44:5
+  --> $DIR/if-without-else-as-fn-expr.rs:39:5
    |
 LL |   fn foo3_let(bar: usize) -> usize {
    |                              ----- expected `usize` because of this return type
@@ -158,7 +90,6 @@ LL | |     }
    = note: `if` expressions without `else` evaluate to `()`
    = help: consider adding an `else` block that evaluates to the expected type
 
-error: aborting due to 12 previous errors
+error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0308, E0317.
-For more information about an error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0317`.

src/test/ui/issues/issue-50577.rs

@@ -2,6 +2,5 @@ fn main() {
     enum Foo {
         Drop = assert_eq!(1, 1)
         //~^ ERROR if may be missing an else clause
-        //~| ERROR mismatched types [E0308]
     }
 }

src/test/ui/issues/issue-50577.stderr

@@ -1,13 +1,3 @@
-error[E0308]: mismatched types
-  --> $DIR/issue-50577.rs:3:16
-   |
-LL |         Drop = assert_eq!(1, 1)
-   |                ^^^^^^^^^^^^^^^^ expected isize, found ()
-   |
-   = note: expected type `isize`
-              found type `()`
-   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
-
 error[E0317]: if may be missing an else clause
   --> $DIR/issue-50577.rs:3:16
    |
@@ -23,7 +13,6 @@ LL |         Drop = assert_eq!(1, 1)
    = help: consider adding an `else` block that evaluates to the expected type
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0308, E0317.
-For more information about an error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0317`.