PmCheck: Desugar string literal patterns with -XRebindableSyntax correctly (#18708)

Fixes #18708.

3 files changed, 27 insertions, 0 deletions

diff --git a/testsuite/tests/pmcheck/should_compile/T18708.hs b/testsuite/tests/pmcheck/should_compile/T18708.hs
new file mode 100644
index 0000000000..8eafb69a76
--- /dev/null
+++ b/testsuite/tests/pmcheck/should_compile/T18708.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE OverloadedStrings        #-}
+{-# LANGUAGE RebindableSyntax         #-}
+
+module A (main) where
+
+import           Prelude
+import           Data.Text
+
+
+fromString :: String -> Text
+fromString = pack
+
+y :: Text
+y = "y"
+
+main :: IO ()
+main =  do
+  case y of
+    "y" -> return ()
+  return ()
diff --git a/testsuite/tests/pmcheck/should_compile/T18708.stderr b/testsuite/tests/pmcheck/should_compile/T18708.stderr
new file mode 100644
index 0000000000..5949d92970
--- /dev/null
+++ b/testsuite/tests/pmcheck/should_compile/T18708.stderr
@@ -0,0 +1,5 @@
+
+T18708.hs:18:3: warning: [-Wincomplete-patterns (in -Wextra)]
+    Pattern match(es) are non-exhaustive
+    In a case alternative:
+        Patterns not matched: p where p is not one of {"y"}
diff --git a/testsuite/tests/pmcheck/should_compile/all.T b/testsuite/tests/pmcheck/should_compile/all.T
index bd5fc60f63..862c5e134a 100644
--- a/testsuite/tests/pmcheck/should_compile/all.T
+++ b/testsuite/tests/pmcheck/should_compile/all.T
@@ -148,6 +148,8 @@ test('T18572', normal, compile,
      ['-fwarn-incomplete-patterns -fwarn-incomplete-uni-patterns -fwarn-overlapping-patterns'])
 test('T18670', normal, compile,
      ['-fwarn-incomplete-patterns -fwarn-overlapping-patterns'])
+test('T18708', normal, compile,
+     ['-fwarn-incomplete-patterns -fwarn-overlapping-patterns'])
 
 # Other tests
 test('pmc001', [], compile,