Rollup merge of #138959 - meithecatte:matchpair-place-option, r=Zalathar

Revert "Make MatchPairTree::place non-optional"

Reverts a part of #137875. Fixes #138958.

cc `@Zalathar`

compiler/rustc_mir_build/src/builder/matches/match_pair.rs

@@ -115,7 +115,6 @@ pub(super) fn for_pattern(
             place_builder = place_builder.project(ProjectionElem::OpaqueCast(pattern.ty));
         }
 
-        // Place can be none if the pattern refers to a non-captured place in a closure.
         let place = place_builder.try_to_place(cx);
         let mut subpairs = Vec::new();
         let test_case = match pattern.kind {
@@ -321,7 +320,7 @@ pub(super) fn for_pattern(
         if let Some(test_case) = test_case {
             // This pattern is refutable, so push a new match-pair node.
             match_pairs.push(MatchPairTree {
-                place: place.expect("refutable patterns should always have a place to inspect"),
+                place,
                 test_case,
                 subpairs,
                 pattern_ty: pattern.ty,

compiler/rustc_mir_build/src/builder/matches/mod.rs

@@ -1279,7 +1279,13 @@ fn as_range(&self) -> Option<&PatRange<'tcx>> {
 #[derive(Debug, Clone)]
 pub(crate) struct MatchPairTree<'tcx> {
     /// This place...
-    place: Place<'tcx>,
+    ///
+    /// ---
+    /// This can be `None` if it referred to a non-captured place in a closure.
+    ///
+    /// Invariant: Can only be `None` when `test_case` is `Or`.
+    /// Therefore this must be `Some(_)` after or-pattern expansion.
+    place: Option<Place<'tcx>>,
 
     /// ... must pass this test...
     test_case: TestCase<'tcx>,
@@ -2099,9 +2105,11 @@ fn pick_test(&mut self, candidates: &[&mut Candidate<'tcx>]) -> (Place<'tcx>, Te
         // Extract the match-pair from the highest priority candidate
         let match_pair = &candidates[0].match_pairs[0];
         let test = self.pick_test_for_match_pair(match_pair);
+        // Unwrap is ok after simplification.
+        let match_place = match_pair.place.unwrap();
         debug!(?test, ?match_pair);
 
-        (match_pair.place, test)
+        (match_place, test)
     }
 
     /// Given a test, we partition the input candidates into several buckets.

compiler/rustc_mir_build/src/builder/matches/test.rs

@@ -470,8 +470,11 @@ pub(super) fn sort_candidate(
         // than one, but it'd be very unusual to have two sides that
         // both require tests; you'd expect one side to be simplified
         // away.)
-        let (match_pair_index, match_pair) =
-            candidate.match_pairs.iter().enumerate().find(|&(_, mp)| mp.place == test_place)?;
+        let (match_pair_index, match_pair) = candidate
+            .match_pairs
+            .iter()
+            .enumerate()
+            .find(|&(_, mp)| mp.place == Some(test_place))?;
 
         // If true, the match pair is completely entailed by its corresponding test
         // branch, so it can be removed. If false, the match pair is _compatible_
@@ -514,7 +517,7 @@ pub(super) fn sort_candidate(
                     candidate
                         .match_pairs
                         .iter()
-                        .any(|mp| mp.place == test_place && is_covering_range(&mp.test_case))
+                        .any(|mp| mp.place == Some(test_place) && is_covering_range(&mp.test_case))
                 };
                 if sorted_candidates
                     .get(&TestBranch::Failure)

compiler/rustc_mir_build/src/builder/matches/util.rs

@@ -173,10 +173,14 @@ fn visit_match_pair(&mut self, match_pair: &MatchPairTree<'tcx>) {
             // }
             // ```
             // Hence we fake borrow using a deep borrow.
-            self.fake_borrow(match_pair.place, FakeBorrowKind::Deep);
+            if let Some(place) = match_pair.place {
+                self.fake_borrow(place, FakeBorrowKind::Deep);
+            }
         } else {
             // Insert a Shallow borrow of any place that is switched on.
-            self.fake_borrow(match_pair.place, FakeBorrowKind::Shallow);
+            if let Some(place) = match_pair.place {
+                self.fake_borrow(place, FakeBorrowKind::Shallow);
+            }
 
             for subpair in &match_pair.subpairs {
                 self.visit_match_pair(subpair);

tests/ui/closures/upvar-or-pattern-issue-138958.rs

@@ -0,0 +1,11 @@
+//@ edition:2024
+//@ check-pass
+
+pub fn f(x: (u32, u32)) {
+    let _ = || {
+        let ((0, a) | (a, _)) = x;
+        a
+    };
+}
+
+fn main() {}