Rollup merge of #101360 - compiler-errors:multiple-closure-bounds, r=petrochenkov

Point out incompatible closure bounds

Fixes #100295

src/test/ui/closures/multiple-fn-bounds.rs

@@ -0,0 +1,15 @@
+fn foo<F: Fn(&char) -> bool + Fn(char) -> bool>(f: F) {
+    //~^ NOTE required by a bound in `foo`
+    //~| NOTE required by this bound in `foo`
+    //~| NOTE closure inferred to have a different signature due to this bound
+    todo!();
+}
+
+fn main() {
+    let v = true;
+    foo(move |x| v);
+    //~^ ERROR type mismatch in closure arguments
+    //~| NOTE expected closure signature
+    //~| NOTE expected due to this
+    //~| NOTE found signature defined here
+}

src/test/ui/closures/multiple-fn-bounds.stderr

@@ -0,0 +1,24 @@
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/multiple-fn-bounds.rs:10:5
+   |
+LL |     foo(move |x| v);
+   |     ^^^ -------- found signature defined here
+   |     |
+   |     expected due to this
+   |
+   = note: expected closure signature `fn(char) -> _`
+              found closure signature `for<'a> fn(&'a char) -> _`
+note: closure inferred to have a different signature due to this bound
+  --> $DIR/multiple-fn-bounds.rs:1:11
+   |
+LL | fn foo<F: Fn(&char) -> bool + Fn(char) -> bool>(f: F) {
+   |           ^^^^^^^^^^^^^^^^^
+note: required by a bound in `foo`
+  --> $DIR/multiple-fn-bounds.rs:1:31
+   |
+LL | fn foo<F: Fn(&char) -> bool + Fn(char) -> bool>(f: F) {
+   |                               ^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0631`.