always check for mixed deref pattern and normal constructors

This makes it work for box patterns and in rust-analyzer.

1 files changed, 4 insertions, 1 deletions

diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs
index c348cd508f9..fb94b4afebb 100644
--- a/compiler/rustc_pattern_analysis/src/usefulness.rs
+++ b/compiler/rustc_pattern_analysis/src/usefulness.rs
@@ -720,7 +720,7 @@ use tracing::{debug, instrument};
 use self::PlaceValidity::*;
 use crate::constructor::{Constructor, ConstructorSet, IntRange};
 use crate::pat::{DeconstructedPat, PatId, PatOrWild, WitnessPat};
-use crate::{MatchArm, PatCx, PrivateUninhabitedField};
+use crate::{MatchArm, PatCx, PrivateUninhabitedField, checks};
 #[cfg(not(feature = "rustc"))]
 pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
     f()
@@ -1836,6 +1836,9 @@ pub fn compute_match_usefulness<'p, Cx: PatCx>(
     scrut_validity: PlaceValidity,
     complexity_limit: usize,
 ) -> Result<UsefulnessReport<'p, Cx>, Cx::Error> {
+    // The analysis doesn't support deref patterns mixed with normal constructors; error if present.
+    checks::detect_mixed_deref_pat_ctors(tycx, arms)?;
+
     let mut cx = UsefulnessCtxt {
         tycx,
         branch_usefulness: FxHashMap::default(),