diff options
| author | Simon Peyton Jones <simonpj@microsoft.com> | 2017-01-12 10:59:08 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2017-01-12 12:58:03 +0000 |
| commit | f5f6d4237b87f5d0e3e0a05e4cfc52bb3c0e4ad9 (patch) | |
| tree | cd231caa17a831190e7cac61d9a582aafbc0a0bb /testsuite/tests/typecheck/should_fail/T12921.hs | |
| parent | 89ce9cd3e011982eb0bcd7e11ec70ef8457b02be (diff) | |
| download | haskell-f5f6d4237b87f5d0e3e0a05e4cfc52bb3c0e4ad9.tar.gz | |
Fix top-level constraint handling (Trac #12921)
Some out-of-scope errors were not being reported if anyone
throws an un-caught exception in the TcM monad. That led to
ghc: panic! (the 'impossible' happened)
initTc: unsolved constraints
I fixed this
* Splitting captureConstraints to use an auxilliary
tryCaptureConstraints (which never fails)
* Define a new TcSimplify.captureTopConstraints (replacing
the old TcRnMonad.captureTopConstraints), which reports
any unsolved out-of-scope constraints before propagating
the exception
That in turn allowed me to do some tidying up of the static-constraint
machinery, reducing duplication.
Also solves #13106.
Diffstat (limited to 'testsuite/tests/typecheck/should_fail/T12921.hs')
| -rw-r--r-- | testsuite/tests/typecheck/should_fail/T12921.hs | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_fail/T12921.hs b/testsuite/tests/typecheck/should_fail/T12921.hs new file mode 100644 index 0000000000..4b4aa2754a --- /dev/null +++ b/testsuite/tests/typecheck/should_fail/T12921.hs @@ -0,0 +1,9 @@ +{-# LANGUAGE OverloadedStrings #-} +module T12921 (stat) where + +{-# ANN module "HLint: ignore Reduce duplication" #-} + +stat :: Int -> Int +stat = choice [] + +-- 'choice' is deliberately out of scope in this test |