Fix desugaring with unboxed types (#19883)wip/T19883

3 files changed, 21 insertions, 1 deletions

diff --git a/compiler/GHC/HsToCore/Expr.hs b/compiler/GHC/HsToCore/Expr.hs
index 6bf900da89..75566a03a6 100644
--- a/compiler/GHC/HsToCore/Expr.hs
+++ b/compiler/GHC/HsToCore/Expr.hs
@@ -797,7 +797,9 @@ dsSyntaxExpr (SyntaxExprTc { syn_expr      = expr
        ; core_res_wrap  <- dsHsWrapper res_wrap
        ; let wrapped_args = zipWithEqual "dsSyntaxExpr" ($) core_arg_wraps arg_exprs
        ; dsWhenNoErrs (zipWithM_ dsNoLevPolyExpr wrapped_args [ mk_msg n | n <- [1..] ])
-                      (\_ -> core_res_wrap (mkApps fun wrapped_args)) }
+                      (\_ -> core_res_wrap (mkCoreApps fun wrapped_args)) }
+                      -- Use mkCoreApps instead of mkApps:
+                      -- unboxed types are possible with RebindableSyntax (#19883)
   where
     mk_msg n = LevityCheckInSyntaxExpr (DsArgNum n) expr
 dsSyntaxExpr NoSyntaxExprTc _ = panic "dsSyntaxExpr"
diff --git a/testsuite/tests/deSugar/should_compile/T19883.hs b/testsuite/tests/deSugar/should_compile/T19883.hs
new file mode 100644
index 0000000000..80cfc9860c
--- /dev/null
+++ b/testsuite/tests/deSugar/should_compile/T19883.hs
@@ -0,0 +1,17 @@
+{-# Language DataKinds #-}
+{-# Language NoImplicitPrelude #-}
+{-# Language RebindableSyntax #-}
+
+module T19883 where
+
+import GHC.Types
+import qualified Prelude
+
+class Eq (a :: TYPE r) where
+  (==) :: a -> a -> Bool
+
+class Num (a :: TYPE r) where
+  fromInteger :: Prelude.Integer -> a
+
+roundDef :: forall (a :: TYPE IntRep) . (Eq a, Num a) => a -> ()
+roundDef 0 = ()
diff --git a/testsuite/tests/deSugar/should_compile/all.T b/testsuite/tests/deSugar/should_compile/all.T
index 6e6f486b4a..89583f4bb8 100644
--- a/testsuite/tests/deSugar/should_compile/all.T
+++ b/testsuite/tests/deSugar/should_compile/all.T
@@ -111,3 +111,4 @@ test('T13208', [], makefile_test, ['T13208'])
 test('T16615', normal, compile, ['-ddump-ds -dsuppress-uniques'])
 test('T18112', [grep_errmsg('cast')], compile, ['-ddump-ds'])
 test('T19969', normal, compile, ['-ddump-simpl -dsuppress-uniques'])
+test('T19883', normal, compile, [''])