1 files changed, 24 insertions, 15 deletions
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index cbcf9cd12..007f3b55e 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -481,6 +481,22 @@ fn construct_fn<'tcx>(
         (None, fn_sig.output())
     };
 
+    if let Some(custom_mir_attr) =
+        tcx.hir().attrs(fn_id).iter().find(|attr| attr.name_or_empty() == sym::custom_mir)
+    {
+        return custom::build_custom_mir(
+            tcx,
+            fn_def.did.to_def_id(),
+            thir,
+            expr,
+            arguments,
+            return_ty,
+            return_ty_span,
+            span_with_body,
+            custom_mir_attr,
+        );
+    }
+
     let infcx = tcx.infer_ctxt().build();
     let mut builder = Builder::new(
         thir,
@@ -908,7 +924,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         scope,
                         expr.span,
                         &pat,
-                        matches::ArmHasGuard(false),
+                        None,
                         Some((Some(&place), span)),
                     );
                     let place_builder = PlaceBuilder::from(local);
@@ -932,20 +948,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         original_source_scope: SourceScope,
         pattern_span: Span,
     ) {
-        let tcx = self.tcx;
-        let current_root = tcx.maybe_lint_level_root_bounded(arg_hir_id, self.hir_id);
-        let parent_root = tcx.maybe_lint_level_root_bounded(
-            self.source_scopes[original_source_scope]
-                .local_data
-                .as_ref()
-                .assert_crate_local()
-                .lint_root,
-            self.hir_id,
-        );
-        if current_root != parent_root {
-            self.source_scope =
-                self.new_source_scope(pattern_span, LintLevel::Explicit(current_root), None);
-        }
+        let parent_id = self.source_scopes[original_source_scope]
+            .local_data
+            .as_ref()
+            .assert_crate_local()
+            .lint_root;
+        self.maybe_new_source_scope(pattern_span, None, arg_hir_id, parent_id);
     }
 
     fn get_unit_temp(&mut self) -> Place<'tcx> {
@@ -1033,6 +1041,7 @@ pub(crate) fn parse_float_into_scalar(
 
 mod block;
 mod cfg;
+mod custom;
 mod expr;
 mod matches;
 mod misc;