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Diffstat (limited to 'docs/users_guide/using-warnings.rst')
| -rw-r--r-- | docs/users_guide/using-warnings.rst | 64 |
1 files changed, 23 insertions, 41 deletions
diff --git a/docs/users_guide/using-warnings.rst b/docs/users_guide/using-warnings.rst index dc21cd468f..840c66eef6 100644 --- a/docs/users_guide/using-warnings.rst +++ b/docs/users_guide/using-warnings.rst @@ -517,32 +517,18 @@ of ``-W(no-)*``. This option is off by default. .. ghc-flag:: -Wnoncanonical-monadfail-instances - :shortdesc: warn when ``Monad`` or ``MonadFail`` instances have + :shortdesc: *(deprecated)* + warn when ``Monad`` or ``MonadFail`` instances have noncanonical definitions of ``fail``. - See flag description in :ref:`options-sanity` for more details. :type: dynamic :reverse: -Wno-noncanonical-monadfail-instances :category: - Warn if noncanonical ``Monad`` or ``MonadFail`` instances - declarations are detected. - - When this warning is enabled, the following conditions are verified: - - In ``Monad`` instances declarations warn if any of the following - conditions does not hold: - - * If ``fail`` is defined it must be canonical - (i.e. ``fail = Control.Monad.Fail.fail``). - - Moreover, in ``MonadFail`` instance declarations: - - * Warn if ``fail`` is defined backwards - (i.e. ``fail = Control.Monad.fail``). - - See also :ghc-flag:`-Wmissing-monadfail-instances`. - - This option is off by default. + This warning is deprecated. It no longer has any effect since GHC 8.8. + It was used during the transition period of the MonadFail proposal, + to detect when an instance of the ``Monad`` class was not defined + via ``MonadFail``, or when a ``MonadFail`` instance was defined + backwards, using the method in ``Monad``. .. ghc-flag:: -Wnoncanonical-monoid-instances :shortdesc: warn when ``Semigroup`` or ``Monoid`` instances have @@ -571,25 +557,17 @@ of ``-W(no-)*``. :ghc-flag:`-Wcompat` option group. .. ghc-flag:: -Wmissing-monadfail-instances - :shortdesc: Warn when a failable pattern is used in a do-block that does + :shortdesc: *(deprecated)* + Warn when a failable pattern is used in a do-block that does not have a ``MonadFail`` instance. :type: dynamic :reverse: -Wno-missing-monadfail-instances :category: - .. index:: - single: MFP - single: MonadFail Proposal - - Warn when a failable pattern is used in a do-block that does not have a - ``MonadFail`` instance. - - See also :ghc-flag:`-Wnoncanonical-monadfail-instances`. - - Being part of the :ghc-flag:`-Wcompat` option group, this warning is off by - default, but will be switched on in a future GHC release, as part of - the `MonadFail Proposal (MFP) - <https://gitlab.haskell.org/haskell/prime/-/wikis/libraries/proposals/monad-fail>`__. + This warning is deprecated. It no longer has any effect since GHC 8.8. + It was used during the transition period of the MonadFail proposal, + to warn when a failable pattern is used in a do-block that does not have + a ``MonadFail`` instance. .. ghc-flag:: -Wsemigroup :shortdesc: warn when a ``Monoid`` is not ``Semigroup``, and on non- @@ -836,23 +814,27 @@ of ``-W(no-)*``. ``toInteger``, ``toRational``, ``fromIntegral``, and ``realToFrac``. .. ghc-flag:: -Wimplicit-kind-vars - :shortdesc: warn when kind variables are implicitly quantified over. + :shortdesc: *(deprecated)* warn when kind variables are + implicitly quantified over. :type: dynamic :reverse: -Wno-implicit-kind-vars :category: - .. index:: - single: implicit prelude, warning - - Have the compiler warn if a kind variable is not explicitly quantified + This warning is deprecated. It no longer has any effect since GHC 8.10. + It was used to detect if a kind variable is not explicitly quantified over. For instance, the following would produce a warning: :: f :: forall (a :: k). Proxy a - This can be fixed by explicitly quantifying over ``k``: :: + This is now an error and can be fixed by explicitly quantifying + over ``k``: :: f :: forall k (a :: k). Proxy a + or :: + + f :: forall {k} (a :: k). Proxy a + .. ghc-flag:: -Wimplicit-lift :shortdesc: warn about implicit ``lift`` in Template Haskell quotes :type: dynamic |