[EPA] exact print linear arrows.

Closes #19903

Note: the normal ppr does not reproduce unicode linear arrows, so that
part of the normal printing test is ommented out in the Makefile for
this test. See #18846

3 files changed, 38 insertions, 0 deletions

diff --git a/testsuite/tests/printer/Makefile b/testsuite/tests/printer/Makefile
index 1d0fc14f87..e8bbe7c079 100644
--- a/testsuite/tests/printer/Makefile
+++ b/testsuite/tests/printer/Makefile
@@ -558,6 +558,12 @@ InTreeAnnotations1:
 	$(CHECK_PPR)   $(LIBDIR) InTreeAnnotations1.hs
 	$(CHECK_EXACT) $(LIBDIR) InTreeAnnotations1.hs
 
+.PHONY: PprLinearArrow
+PprLinearArrow:
+	# $(CHECK_PPR)   $(LIBDIR) PprLinearArrow.hs
+	$(CHECK_EXACT) $(LIBDIR) PprLinearArrow.hs
+
+
 .PHONY: Test19784
 Test19784:
 	$(CHECK_PPR)   $(LIBDIR) Test19784.hs
diff --git a/testsuite/tests/printer/PprLinearArrow.hs b/testsuite/tests/printer/PprLinearArrow.hs
new file mode 100644
index 0000000000..1bf995ce6d
--- /dev/null
+++ b/testsuite/tests/printer/PprLinearArrow.hs
@@ -0,0 +1,26 @@
+{-# LANGUAGE LinearTypes, DataKinds, UnicodeSyntax #-}
+
+module PprLinearArrow where
+
+import GHC.Types (Multiplicity(One, Many))
+
+n1 :: a %1 -> b
+n1 = undefined
+
+u1 :: a %1 → b
+u1 = undefined
+
+n2 :: a  %(Many) -> b
+n2 = undefined
+
+u2 :: a  %(Many) → b
+u2 = undefined
+
+m3 :: a ⊸ b
+m3 = undefined
+
+n4 :: a %p  -> b
+n4 = undefined
+
+u4 :: a %p  → b
+u4 = undefined
diff --git a/testsuite/tests/printer/all.T b/testsuite/tests/printer/all.T
index 916ed6bbee..e936cdc64e 100644
--- a/testsuite/tests/printer/all.T
+++ b/testsuite/tests/printer/all.T
@@ -124,12 +124,18 @@ test('PprRecordDotSyntaxA', ignore_stderr, makefile_test, ['PprRecordDotSyntaxA'
 test('CommentsTest', ignore_stderr, makefile_test, ['CommentsTest'])
 test('InTreeAnnotations1', ignore_stderr, makefile_test, ['InTreeAnnotations1'])
 
+
+# Normal ppr does not reproduce unicode linear arrows, commented out
+# in the Makefile for this test. See #18846
+test('PprLinearArrow', ignore_stderr, makefile_test, ['PprLinearArrow'])
+
 test('Test19784', ignore_stderr, makefile_test, ['Test19784'])
 test('Test19798', ignore_stderr, makefile_test, ['Test19798'])
 
 # The exact printing manages the extra semicolons, normal ppr not, so
 # disabled in the Makefile for this test.
 test('Test19813', ignore_stderr, makefile_test, ['Test19813'])
+
 test('Test19814', ignore_stderr, makefile_test, ['Test19814'])
 test('Test19821', ignore_stderr, makefile_test, ['Test19821'])
 test('Test19834', ignore_stderr, makefile_test, ['Test19834'])