Rollup merge of #115643 - bvanjoi:fix-115203, r=RalfJung,oli-obk

fix: return early when has tainted in mir-lint

Fixes #115203

`a[..]` is of indeterminate size, it had been reported error during borrow check, therefore we skip the mir lint process.

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -39,6 +39,10 @@
 
 impl<'tcx> MirLint<'tcx> for ConstProp {
     fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
+        if body.tainted_by_errors.is_some() {
+            return;
+        }
+
         // will be evaluated by miri and produce its errors there
         if body.source.promoted.is_some() {
             return;

tests/ui/unsized/issue-115203.rs

@@ -0,0 +1,11 @@
+// compile-flags: --emit link
+
+fn main() {
+    let a: [i32; 0] = [];
+    match [a[..]] {
+        //~^ ERROR cannot move a value of type `[i32]
+        //~| ERROR cannot move out of type `[i32]`, a non-copy slice
+        [[]] => (),
+        _ => (),
+    }
+}

tests/ui/unsized/issue-115203.stderr

@@ -0,0 +1,19 @@
+error[E0161]: cannot move a value of type `[i32]`
+  --> $DIR/issue-115203.rs:5:12
+   |
+LL |     match [a[..]] {
+   |            ^^^^^ the size of `[i32]` cannot be statically determined
+
+error[E0508]: cannot move out of type `[i32]`, a non-copy slice
+  --> $DIR/issue-115203.rs:5:12
+   |
+LL |     match [a[..]] {
+   |            ^^^^^
+   |            |
+   |            cannot move out of here
+   |            move occurs because value has type `[i32]`, which does not implement the `Copy` trait
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0161, E0508.
+For more information about an error, try `rustc --explain E0161`.