Suggest similar names when reporting types in terms (#19978)

This fixes an error message regression.

4 files changed, 50 insertions, 2 deletions

diff --git a/testsuite/tests/module/mod132.stderr b/testsuite/tests/module/mod132.stderr
index 37c934c70f..31d9c8eeb6 100644
--- a/testsuite/tests/module/mod132.stderr
+++ b/testsuite/tests/module/mod132.stderr
@@ -1,7 +1,8 @@
 
 mod132.hs:6:7: error:
-     Illegal term-level use of the type constructor ‘Foo’
+    • Illegal term-level use of the type constructor ‘Foo’
         imported from ‘Mod132_B’ at mod132.hs:4:1-15
         (and originally defined in ‘Mod132_A’ at Mod132_A.hs:3:1-14)
-     In the expression: Foo
+      Perhaps you meant variable ‘foo’ (line 6)
+    • In the expression: Foo
       In an equation for ‘foo’: foo = Foo
diff --git a/testsuite/tests/typecheck/should_fail/T19978.hs b/testsuite/tests/typecheck/should_fail/T19978.hs
new file mode 100644
index 0000000000..fd96697db9
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T19978.hs
@@ -0,0 +1,25 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module T19978 where
+
+-----------------------------------------
+--       Type constructor in terms     --
+-----------------------------------------
+ex1 = Bool
+
+-- to be suggested instead of "Bool" in "ex1":
+data T1 = Bowl
+bool = Bowl
+
+ex2 = Let  -- should suggest Left (imported from Prelude)
+
+-----------------------------------------
+--        Type variable in terms       --
+-----------------------------------------
+
+ex3 :: forall mytv. mytv
+ex3 = mytv
+
+-- to be suggested instead of "mytv" in "ex3":
+data T3 = Mytv
+myvv = Mytv
diff --git a/testsuite/tests/typecheck/should_fail/T19978.stderr b/testsuite/tests/typecheck/should_fail/T19978.stderr
new file mode 100644
index 0000000000..7f41c37ad4
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T19978.stderr
@@ -0,0 +1,21 @@
+
+T19978.hs:8:7: error:
+    • Illegal term-level use of the type constructor ‘Bool’
+        imported from ‘Prelude’ at T19978.hs:3:8-13
+        (and originally defined in ‘GHC.Types’)
+      Perhaps you meant one of these:
+        ‘Bowl’ (line 11), variable ‘bool’ (line 12)
+    • In the expression: Bool
+      In an equation for ‘ex1’: ex1 = Bool
+
+T19978.hs:14:7: error:
+    • Data constructor not in scope: Let
+    • Perhaps you meant ‘Left’ (imported from Prelude)
+
+T19978.hs:21:7: error:
+    • Illegal term-level use of the type variable ‘mytv’
+        bound at T19978.hs:20:15
+      Perhaps you meant one of these:
+        data constructor ‘Mytv’ (line 24), ‘myvv’ (line 25)
+    • In the expression: mytv
+      In an equation for ‘ex3’: ex3 = mytv
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index 54af02c6f5..b776f1d5dd 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -631,3 +631,4 @@ test('T19415', normal, compile_fail, [''])
 test('T19615', normal, compile_fail, [''])
 test('T17817', normal, compile_fail, [''])
 test('T17817_elab', normal, compile_fail, ['-fprint-typechecker-elaboration'])
+test('T19978', normal, compile_fail, [''])