Rollup merge of rust-lang#100452 - ouz-a:issue-93242, r=jackh726

Fake capture closures if typeck results are empty

This ICE happens because `closure_min_captures` is empty, the reason it's empty is with the 2021 edition `enable_precise_capture` is set to true, which makes it so that we can't fake capture any information because that result of the `unwrap` is none hence the ICE.

Other solution is editing [maybe_read_scrutinee](https://doc.rust-lang.org/nightly/nightly-rustc/src/rustc_typeck/expr_use_visitor.rs.html#453-463) to this since empty slice contains no sub patterns.

Fixes rust-lang#93242

```rust
PatKind::Slice(_, ref slice, _) => {
    if slice.is_none(){
    need_to_be_read = true;
    }
}
// instead of
PatKind::Or(_)
| PatKind::Box(_)
| PatKind::Slice(..)
| PatKind::Ref(..)
| PatKind::Wild => {}
```

compiler/rustc_hir_typeck/src/upvar.rs

@@ -231,7 +231,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // We now fake capture information for all variables that are mentioned within the closure
         // We do this after handling migrations so that min_captures computes before
-        if !enable_precise_capture(self.tcx, span) {
+        if !enable_precise_capture(self.tcx, span)
+            // (ouz-a) #93242 - ICE happens because closure_min_captures is empty with
+            // 2021 edition, because it sets `enable_precise_capture` to true, which won't allow us
+            // fake capture information this check sidesteps that and avoids the ICE.
+            || (infer_kind == None && self.typeck_results.borrow().closure_min_captures.is_empty())
+        {
             let mut capture_information: InferredCaptureInformation<'tcx> = Default::default();
 
             if let Some(upvars) = self.tcx.upvars_mentioned(closure_def_id) {

src/test/ui/closures/issue-93242.rs

@@ -0,0 +1,11 @@
+// check-pass
+// edition:2021
+
+pub fn something(path: &[usize]) -> impl Fn() -> usize + '_ {
+    move || match path {
+        [] => 0,
+        _ => 1,
+    }
+}
+
+fn main(){}