Make okConIdOcc recognize unboxed tuples

Summary:
`okConIdOcc`, which validates that a type or constructor name is valid
for splicing using Template Haskell, has a special case for tuples, but
neglects to look for unboxed tuples, causing some sensible Template Haskell
code involving unboxed tuples to be rejected.

Fixes #12407.

Test Plan: make test TEST=T12407

Reviewers: austin, bgamari, hvr, goldfire

Reviewed By: goldfire

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2410

GHC Trac Issues: #12407

1 files changed, 17 insertions, 0 deletions

diff --git a/testsuite/tests/th/T12407.hs b/testsuite/tests/th/T12407.hs
new file mode 100644
index 0000000000..daa3e34c6f
--- /dev/null
+++ b/testsuite/tests/th/T12407.hs
@@ -0,0 +1,17 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE UnboxedTuples #-}
+module T12407 where
+
+import Language.Haskell.TH.Lib
+import Language.Haskell.TH.Syntax
+
+$(do let ubxTup = conT (unboxedTupleTypeName 2) `appT` conT ''Int
+                                                `appT` conT ''Int
+     x <- newName "x"
+     y <- newName "y"
+
+     [d| f :: $(ubxTup) -> $(ubxTup)
+         f $(conP (unboxedTupleDataName 2) [varP x, varP y])
+             = $(conE (unboxedTupleDataName 2) `appE` varE x
+                                               `appE` varE y)
+      |])