Easy way to defer type errors (implements #8353)

Added load! and reload! commands, effectively setting
"-fdefer-type-errors" before loading a file and
unsetting it after loading if it has not been set before.

Differential Revision: https://phabricator.haskell.org/D960

4 files changed, 55 insertions, 0 deletions

diff --git a/testsuite/tests/ghci/scripts/Defer03.hs b/testsuite/tests/ghci/scripts/Defer03.hs
new file mode 100755
index 0000000000..b91a7ac8d0
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/Defer03.hs
@@ -0,0 +1,7 @@
+module Main where
+
+a :: Int
+a = 'p'
+
+main :: IO ()
+main = print "No errors!"
diff --git a/testsuite/tests/ghci/scripts/T8353.script b/testsuite/tests/ghci/scripts/T8353.script
new file mode 100644
index 0000000000..d93fb6e4cb
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T8353.script
@@ -0,0 +1,22 @@
+-- Test :load! and :reload!
+
+-- main is independent of functions with type errors and thus
+-- executable after load
+-- warnings on type errors are emitted nevertheless
+:load!   Defer03
+
+-- fails to load module due to type errors
+:load    Defer03
+
+-- succeeds again to load module
+:reload!
+
+-- also succeeds, because the module has not been touched since load
+:reload
+
+-- now, after touching, reloading should fail
+:! touch Defer03.hs
+:reload
+
+-- using the deferred version of reload, loading should succeed again
+:reload!
diff --git a/testsuite/tests/ghci/scripts/T8353.stderr b/testsuite/tests/ghci/scripts/T8353.stderr
new file mode 100644
index 0000000000..7303142d10
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T8353.stderr
@@ -0,0 +1,25 @@
+
+Defer03.hs:4:5: warning:
+    Couldn't match expected type ‘Int’ with actual type ‘Char’
+    In the expression: 'p'
+    In an equation for ‘a’: a = 'p'
+
+Defer03.hs:4:5: error:
+    Couldn't match expected type ‘Int’ with actual type ‘Char’
+    In the expression: 'p'
+    In an equation for ‘a’: a = 'p'
+
+Defer03.hs:4:5: warning:
+    Couldn't match expected type ‘Int’ with actual type ‘Char’
+    In the expression: 'p'
+    In an equation for ‘a’: a = 'p'
+
+Defer03.hs:4:5: error:
+    Couldn't match expected type ‘Int’ with actual type ‘Char’
+    In the expression: 'p'
+    In an equation for ‘a’: a = 'p'
+
+Defer03.hs:4:5: warning:
+    Couldn't match expected type ‘Int’ with actual type ‘Char’
+    In the expression: 'p'
+    In an equation for ‘a’: a = 'p'
diff --git a/testsuite/tests/ghci/scripts/all.T b/testsuite/tests/ghci/scripts/all.T
index 747e708aad..1efa0099f1 100755
--- a/testsuite/tests/ghci/scripts/all.T
+++ b/testsuite/tests/ghci/scripts/all.T
@@ -171,6 +171,7 @@ test('T8113', normal, ghci_script, ['T8113.script'])
 test('T8172', when(opsys('mingw32'), normalise_drive_letter),
      ghci_script, ['T8172.script'])
 test('T8215', normal, ghci_script, ['T8215.script'])
+test('T8353', normal, ghci_script, ['T8353.script'])
 test('T8357', normal, ghci_script, ['T8357.script'])
 test('T8383', normal, ghci_script, ['T8383.script'])
 test('T8469', normal, ghci_script, ['T8469.script'])