Rollup merge of #92207 - tmiasko:delay-drop-elaboration-bug, r=jackh726

Delay remaining `span_bug`s in drop elaboration

This follows changes from #67967 and converts remaining `span_bug`s into
delayed bugs, since for const items drop elaboration might be executed
on a MIR which failed borrowck.

Fixes #81708.
Fixes #91816.

2 files changed, 82 insertions, 0 deletions

diff --git a/src/test/ui/mir/drop-elaboration-after-borrowck-error.rs b/src/test/ui/mir/drop-elaboration-after-borrowck-error.rs
new file mode 100644
index 00000000000..c44dd51a5ec
--- /dev/null
+++ b/src/test/ui/mir/drop-elaboration-after-borrowck-error.rs
@@ -0,0 +1,25 @@
+// Regression test for issue 81708 and issue 91816 where running a drop
+// elaboration on a MIR which failed borrowck lead to an ICE.
+
+static A: () = {
+    let a: [String; 1];
+    //~^ ERROR destructors cannot be evaluated at compile-time
+    a[0] = String::new();
+    //~^ ERROR destructors cannot be evaluated at compile-time
+    //~| ERROR use of possibly-uninitialized variable
+};
+
+struct B<T>([T; 1]);
+
+impl<T> B<T> {
+    pub const fn f(mut self, other: T) -> Self {
+        let _this = self;
+        //~^ ERROR destructors cannot be evaluated at compile-time
+        self.0[0] = other;
+        //~^ ERROR destructors cannot be evaluated at compile-time
+        //~| ERROR use of moved value
+        self
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/mir/drop-elaboration-after-borrowck-error.stderr b/src/test/ui/mir/drop-elaboration-after-borrowck-error.stderr
new file mode 100644
index 00000000000..80d5fc7ec67
--- /dev/null
+++ b/src/test/ui/mir/drop-elaboration-after-borrowck-error.stderr
@@ -0,0 +1,57 @@
+error[E0493]: destructors cannot be evaluated at compile-time
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:7:5
+   |
+LL |     a[0] = String::new();
+   |     ^^^^
+   |     |
+   |     statics cannot evaluate destructors
+   |     value is dropped here
+
+error[E0493]: destructors cannot be evaluated at compile-time
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:5:9
+   |
+LL |     let a: [String; 1];
+   |         ^ statics cannot evaluate destructors
+...
+LL | };
+   | - value is dropped here
+
+error[E0381]: use of possibly-uninitialized variable: `a`
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:7:5
+   |
+LL |     a[0] = String::new();
+   |     ^^^^ use of possibly-uninitialized `a`
+
+error[E0493]: destructors cannot be evaluated at compile-time
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:18:9
+   |
+LL |         self.0[0] = other;
+   |         ^^^^^^^^^
+   |         |
+   |         constant functions cannot evaluate destructors
+   |         value is dropped here
+
+error[E0493]: destructors cannot be evaluated at compile-time
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:16:13
+   |
+LL |         let _this = self;
+   |             ^^^^^ constant functions cannot evaluate destructors
+...
+LL |     }
+   |     - value is dropped here
+
+error[E0382]: use of moved value: `self.0`
+  --> $DIR/drop-elaboration-after-borrowck-error.rs:18:9
+   |
+LL |     pub const fn f(mut self, other: T) -> Self {
+   |                    -------- move occurs because `self` has type `B<T>`, which does not implement the `Copy` trait
+LL |         let _this = self;
+   |                     ---- value moved here
+LL |
+LL |         self.0[0] = other;
+   |         ^^^^^^^^^ value used here after move
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0381, E0382, E0493.
+For more information about an error, try `rustc --explain E0381`.