test case for #1743

testsuite/tests/ghc-regress/ghci.debugger/scripts/all.T

@@ -56,6 +56,7 @@ test('break020', normal, ghci_script, ['break020.script'])
 test('break021', normal, ghci_script, ['break021.script'])
 test('break024', normal, ghci_script, ['break024.script'])
 test('break025', expect_broken(1681), ghci_script, ['break025.script'])
+test('break026', expect_broken(1681), ghci_script, ['break026.script'])
 
 test('dynbrk001', normal, ghci_script, ['dynbrk001.script'])
 test('dynbrk002', normal, ghci_script, ['dynbrk002.script'])

testsuite/tests/ghc-regress/ghci.debugger/scripts/break026.hs

+module Test where
+
+import Prelude hiding (foldl)
+
+foldl f c xs = go c xs
+  where go c []     = c
+        go c (x:xs) = go (f c x) xs

testsuite/tests/ghc-regress/ghci.debugger/scripts/break026.script

+:load break026
+:step foldl (+) 0 [1..5]
+:step
+:step
+:step
+:step
+:step
+:force c
+        -- answer should be 1
+
+:load break026
+:step foldl (+) 0 [1..5]
+:step
+:step
+:step
+:step
+:step
+-- a diversion to single-step the evaluation of c:
+:step c `seq` ()
+:step
+-- end diversion
+c
+        -- answer should be 1 again (not 0)

testsuite/tests/ghc-regress/ghci.debugger/scripts/break026.stdout

+Stopped at break026.hs:(5,0)-(7,34)
+_result :: t1 = _
+Stopped at break026.hs:5:15-21
+_result :: t1 = _
+c :: t1 = _
+go :: t1 -> [t] -> t1 = _
+xs :: [t] = _
+Stopped at break026.hs:(6,8)-(7,34)
+_result :: t1 = _
+f :: t1 -> t -> t1 = _
+Stopped at break026.hs:7:22-34
+_result :: t1 = _
+c :: t1 = _
+f :: t1 -> Integer -> t1 = _
+x :: Integer = 1
+xs :: [Integer] = _
+Stopped at break026.hs:(6,8)-(7,34)
+_result :: t1 = _
+f :: t1 -> t -> t1 = _
+Stopped at break026.hs:7:22-34
+_result :: t1 = _
+c :: t1 = _
+f :: t1 -> Integer -> t1 = _
+x :: Integer = 2
+xs :: [Integer] = _
+c = 1
+Stopped at break026.hs:(5,0)-(7,34)
+_result :: t1 = _
+Stopped at break026.hs:5:15-21
+_result :: t1 = _
+c :: t1 = _
+go :: t1 -> [t] -> t1 = _
+xs :: [t] = _
+Stopped at break026.hs:(6,8)-(7,34)
+_result :: t1 = _
+f :: t1 -> t -> t1 = _
+Stopped at break026.hs:7:22-34
+_result :: t1 = _
+c :: t1 = _
+f :: t1 -> Integer -> t1 = _
+x :: Integer = 1
+xs :: [Integer] = _
+Stopped at break026.hs:(6,8)-(7,34)
+_result :: t1 = _
+f :: t1 -> t -> t1 = _
+Stopped at break026.hs:7:22-34
+_result :: t1 = _
+c :: t1 = _
+f :: t1 -> Integer -> t1 = _
+x :: Integer = 2
+xs :: [Integer] = _
+Stopped at break026.hs:7:26-30
+_result :: t1 = _
+c :: t1 = _
+f :: t1 -> Integer -> t1 = _
+x :: Integer = 1
+()
+1