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| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2020-11-13 10:56:20 -0500 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-11-15 03:36:21 -0500 |
| commit | 645444af9eb185684c750c95e4740d301352b2b9 (patch) | |
| tree | 6e2e1136560d7e2acf1075c3974a65c18ae10512 /testsuite/tests/typecheck/should_fail/all.T | |
| parent | d61adb3dace8f52e21f302989182145a0efa103f (diff) | |
| download | haskell-645444af9eb185684c750c95e4740d301352b2b9.tar.gz | |
Use tcSplitForAllInvisTyVars (not tcSplitForAllTyVars) in more places
The use of `tcSplitForAllTyVars` in `tcDataFamInstHeader` was the immediate
cause of #18939, and replacing it with a new `tcSplitForAllInvisTyVars`
function (which behaves like `tcSplitForAllTyVars` but only splits invisible
type variables) fixes the issue. However, this led me to realize that _most_
uses of `tcSplitForAllTyVars` in GHC really ought to be
`tcSplitForAllInvisTyVars` instead. While I was in town, I opted to replace
most uses of `tcSplitForAllTys` with `tcSplitForAllTysInvis` to reduce the
likelihood of such bugs in the future.
I say "most uses" above since there is one notable place where we _do_ want
to use `tcSplitForAllTyVars`: in `GHC.Tc.Validity.forAllTyErr`, which produces
the "`Illegal polymorphic type`" error message if you try to use a higher-rank
`forall` without having `RankNTypes` enabled. Here, we really do want to split
all `forall`s, not just invisible ones, or we run the risk of giving an
inaccurate error message in the newly added `T18939_Fail` test case.
I debated at some length whether I wanted to name the new function
`tcSplitForAllInvisTyVars` or `tcSplitForAllTyVarsInvisible`, but in the end,
I decided that I liked the former better. For consistency's sake, I opted to
rename the existing `splitPiTysInvisible` and `splitPiTysInvisibleN` functions
to `splitInvisPiTys` and `splitPiTysInvisN`, respectively, so that they use the
same naming convention. As a consequence, this ended up requiring a `haddock`
submodule bump.
Fixes #18939.
Diffstat (limited to 'testsuite/tests/typecheck/should_fail/all.T')
| -rw-r--r-- | testsuite/tests/typecheck/should_fail/all.T | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T index 1a260c5dc4..5ce09273a2 100644 --- a/testsuite/tests/typecheck/should_fail/all.T +++ b/testsuite/tests/typecheck/should_fail/all.T @@ -583,6 +583,7 @@ test('T18714', normal, compile_fail, ['']) test('T18723a', normal, compile_fail, ['']) test('T18723b', normal, compile_fail, ['']) test('T18723c', normal, compile_fail, ['']) +test('T18939_Fail', normal, compile_fail, ['']) test('too-many', normal, compile_fail, ['']) test('T18640a', normal, compile_fail, ['']) test('T18640b', normal, compile_fail, ['']) |