Add barest-bones deref patterns

Co-authored-by: Deadbeef <ent3rm4n@gmail.com>

5 files changed, 21 insertions, 1 deletions

diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index d2cbbf9be32..f4f452d474f 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -879,6 +879,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 self.visit_primary_bindings(subpattern, pattern_user_ty.deref(), f);
             }
 
+            PatKind::DerefPattern { ref subpattern } => {
+                self.visit_primary_bindings(subpattern, UserTypeProjections::none(), f);
+            }
+
             PatKind::AscribeUserType {
                 ref subpattern,
                 ascription: thir::Ascription { ref annotation, variance: _ },
diff --git a/compiler/rustc_mir_build/src/build/matches/util.rs b/compiler/rustc_mir_build/src/build/matches/util.rs
index d0d49c13f13..1148cd19a01 100644
--- a/compiler/rustc_mir_build/src/build/matches/util.rs
+++ b/compiler/rustc_mir_build/src/build/matches/util.rs
@@ -256,6 +256,12 @@ impl<'pat, 'tcx> MatchPair<'pat, 'tcx> {
                 subpairs.push(MatchPair::new(place_builder, subpattern, cx));
                 default_irrefutable()
             }
+
+            PatKind::DerefPattern { .. } => {
+                // FIXME(deref_patterns)
+                // Treat it like a wildcard for now.
+                default_irrefutable()
+            }
         };
 
         MatchPair { place, test_case, subpairs, pattern }
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 1ce8da162bf..e04fe31a76f 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -250,6 +250,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 | PatKind::Variant { .. }
                 | PatKind::Leaf { .. }
                 | PatKind::Deref { .. }
+                | PatKind::DerefPattern { .. }
                 | PatKind::Range { .. }
                 | PatKind::Slice { .. }
                 | PatKind::Array { .. } => {
@@ -310,7 +311,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 }
                 visit::walk_pat(self, pat);
             }
-            PatKind::Deref { .. } => {
+            PatKind::Deref { .. } | PatKind::DerefPattern { .. } => {
                 let old_inside_adt = std::mem::replace(&mut self.inside_adt, false);
                 visit::walk_pat(self, pat);
                 self.inside_adt = old_inside_adt;
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 03eda9a9322..f4aed91cd72 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -257,6 +257,9 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                 return self.lower_path(qpath, pat.hir_id, pat.span);
             }
 
+            hir::PatKind::Box(subpattern) if self.tcx.features().deref_patterns => {
+                PatKind::DerefPattern { subpattern: self.lower_pattern(subpattern) }
+            }
             hir::PatKind::Ref(subpattern, _) | hir::PatKind::Box(subpattern) => {
                 PatKind::Deref { subpattern: self.lower_pattern(subpattern) }
             }
diff --git a/compiler/rustc_mir_build/src/thir/print.rs b/compiler/rustc_mir_build/src/thir/print.rs
index d53704f89e7..16c4248a159 100644
--- a/compiler/rustc_mir_build/src/thir/print.rs
+++ b/compiler/rustc_mir_build/src/thir/print.rs
@@ -688,6 +688,12 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
                 self.print_pat(subpattern, depth_lvl + 2);
                 print_indented!(self, "}", depth_lvl + 1);
             }
+            PatKind::DerefPattern { subpattern } => {
+                print_indented!(self, "DerefPattern { ", depth_lvl + 1);
+                print_indented!(self, "subpattern:", depth_lvl + 2);
+                self.print_pat(subpattern, depth_lvl + 2);
+                print_indented!(self, "}", depth_lvl + 1);
+            }
             PatKind::Constant { value } => {
                 print_indented!(self, "Constant {", depth_lvl + 1);
                 print_indented!(self, format!("value: {:?}", value), depth_lvl + 2);