Change the desugaring of `assert!` for better error output

In the desugaring of `assert!`, we now expand to a `match` expression
instead of `if !cond {..}`.

The span of incorrect conditions will point only at the expression, and not
the whole `assert!` invocation.

```
error[E0308]: mismatched types
  --> $DIR/issue-14091.rs:2:13
   |
LL |     assert!(1,1);
   |             ^ expected `bool`, found integer
```

We no longer mention the expression needing to implement the `Not` trait.

```
error[E0308]: mismatched types
  --> $DIR/issue-14091-2.rs:15:13
   |
LL |     assert!(x, x);
   |             ^ expected `bool`, found `BytePos`
```

`assert!(val)` now desugars to:

```rust
match val {
    true => {},
    _ => $crate::panic::panic_2021!(),
}
```

Fix #122159.

We make some minor changes to some diagnostics to avoid span overlap on
type mismatch or inverted "expected"/"found" on type errors.

We remove some unnecessary parens from core, alloc and miri.

address review comments

2 files changed, 37 insertions, 7 deletions

diff --git a/tests/ui/codemap_tests/issue-28308.rs b/tests/ui/codemap_tests/issue-28308.rs
index 81493f8c453..b0e04d0f1f6 100644
--- a/tests/ui/codemap_tests/issue-28308.rs
+++ b/tests/ui/codemap_tests/issue-28308.rs
@@ -1,4 +1,16 @@
 fn main() {
-    assert!("foo");
-    //~^ ERROR cannot apply unary operator `!`
+    assert!("foo"); //~ ERROR mismatched types
+    //~^ NOTE expected `bool`, found `str`
+    //~| NOTE in this expansion of assert!
+    let x = Some(&1);
+    assert!(x); //~ ERROR mismatched types
+    //~^ NOTE expected `bool`, found `Option<&{integer}>`
+    //~| NOTE expected enum `bool`
+    //~| NOTE in this expansion of assert!
+    //~| NOTE in this expansion of assert!
+    assert!(x, ""); //~ ERROR mismatched types
+    //~^ NOTE expected `bool`, found `Option<&{integer}>`
+    //~| NOTE expected enum `bool`
+    //~| NOTE in this expansion of assert!
+    //~| NOTE in this expansion of assert!
 }
diff --git a/tests/ui/codemap_tests/issue-28308.stderr b/tests/ui/codemap_tests/issue-28308.stderr
index 7bc9e05dfc0..e84ceb44aac 100644
--- a/tests/ui/codemap_tests/issue-28308.stderr
+++ b/tests/ui/codemap_tests/issue-28308.stderr
@@ -1,9 +1,27 @@
-error[E0600]: cannot apply unary operator `!` to type `&'static str`
-  --> $DIR/issue-28308.rs:2:5
+error[E0308]: mismatched types
+  --> $DIR/issue-28308.rs:2:13
    |
 LL |     assert!("foo");
-   |     ^^^^^^^^^^^^^^ cannot apply unary operator `!`
+   |             ^^^^^ expected `bool`, found `str`
 
-error: aborting due to 1 previous error
+error[E0308]: mismatched types
+  --> $DIR/issue-28308.rs:6:13
+   |
+LL |     assert!(x);
+   |             ^ expected `bool`, found `Option<&{integer}>`
+   |
+   = note: expected enum `bool`
+              found type `Option<&{integer}>`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-28308.rs:11:13
+   |
+LL |     assert!(x, "");
+   |             ^ expected `bool`, found `Option<&{integer}>`
+   |
+   = note: expected enum `bool`
+              found type `Option<&{integer}>`
+
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0600`.
+For more information about this error, try `rustc --explain E0308`.