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| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2019-07-07 20:14:14 -0400 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-07-11 17:47:41 -0400 |
| commit | b507acebdc3dbec53c54ae07175b39da4066d4f8 (patch) | |
| tree | cb0ee4f150e047927e4499075eb35ca724327dab /testsuite/tests/deriving | |
| parent | 01ec8549871ebc43db3a7e28324222fa739c6531 (diff) | |
| download | haskell-b507acebdc3dbec53c54ae07175b39da4066d4f8.tar.gz | |
Don't typecheck too much (or too little) in DerivingVia (#16923)
Previously, GHC would typecheck the `via` type once per class in a
`deriving` clause, which caused the problems observed in #16923.
This patch restructures some of the functionality in `TcDeriv` and
`TcHsType` to avoid this problem. We now typecheck the `via` type
exactly once per `deriving` clause and *then* typecheck all of the
classes in the clause.
See `Note [Don't typecheck too much in DerivingVia]` in `TcDeriv`
for the full details.
Diffstat (limited to 'testsuite/tests/deriving')
| -rw-r--r-- | testsuite/tests/deriving/should_fail/T16923.hs | 4 | ||||
| -rw-r--r-- | testsuite/tests/deriving/should_fail/T16923.stderr | 6 | ||||
| -rw-r--r-- | testsuite/tests/deriving/should_fail/all.T | 1 |
3 files changed, 11 insertions, 0 deletions
diff --git a/testsuite/tests/deriving/should_fail/T16923.hs b/testsuite/tests/deriving/should_fail/T16923.hs new file mode 100644 index 0000000000..eaa845864b --- /dev/null +++ b/testsuite/tests/deriving/should_fail/T16923.hs @@ -0,0 +1,4 @@ +{-# LANGUAGE DerivingVia #-} +module T16923 where + +data Foo deriving () via Maybe Maybe diff --git a/testsuite/tests/deriving/should_fail/T16923.stderr b/testsuite/tests/deriving/should_fail/T16923.stderr new file mode 100644 index 0000000000..b17e673b30 --- /dev/null +++ b/testsuite/tests/deriving/should_fail/T16923.stderr @@ -0,0 +1,6 @@ + +T16923.hs:4:32: error: + • Expecting one more argument to ‘Maybe’ + Expected a type, but ‘Maybe’ has kind ‘* -> *’ + • In the first argument of ‘Maybe’, namely ‘Maybe’ + In the data declaration for ‘Foo’ diff --git a/testsuite/tests/deriving/should_fail/all.T b/testsuite/tests/deriving/should_fail/all.T index 1f674805a3..bbef97bec7 100644 --- a/testsuite/tests/deriving/should_fail/all.T +++ b/testsuite/tests/deriving/should_fail/all.T @@ -73,6 +73,7 @@ test('T14728b', normal, compile_fail, ['']) test('T14916', normal, compile_fail, ['']) test('T15073', [extra_files(['T15073a.hs'])], multimod_compile_fail, ['T15073', '-v0']) +test('T16923', normal, compile_fail, ['']) test('deriving-via-fail', normal, compile_fail, ['']) test('deriving-via-fail2', normal, compile_fail, ['']) test('deriving-via-fail3', normal, compile_fail, ['']) |