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authorMaxGabriel <feedback.tagher@gmail.com>2020-09-02 22:20:06 -0400
committerMarge Bot <ben+marge-bot@smart-cactus.org>2020-10-09 08:43:11 -0400
commitd360f3438da7f6eb51e217c6697db6fb338c6fd7 (patch)
treed0870b958037e974bd199c4b1237f373c8ef3645
parentaccdb24a086b80fe74776246aa33bce5a920e3c8 (diff)
downloadhaskell-d360f3438da7f6eb51e217c6697db6fb338c6fd7.tar.gz
Document -Wderiving-typeable
Tracking: #18641
-rw-r--r--docs/users_guide/expected-undocumented-flags.txt1
-rw-r--r--docs/users_guide/using-warnings.rst14
2 files changed, 14 insertions, 1 deletions
diff --git a/docs/users_guide/expected-undocumented-flags.txt b/docs/users_guide/expected-undocumented-flags.txt
index 38d12ada42..5801a267bc 100644
--- a/docs/users_guide/expected-undocumented-flags.txt
+++ b/docs/users_guide/expected-undocumented-flags.txt
@@ -4,7 +4,6 @@
--show-packages
-Onot
-Walternative-layout-rule-transitional
--Wderiving-typeable
-XAlternativeLayoutRule
-XAlternativeLayoutRuleTransitional
-XAutoDeriveTypeable
diff --git a/docs/users_guide/using-warnings.rst b/docs/users_guide/using-warnings.rst
index 04fb591ca3..5f07299258 100644
--- a/docs/users_guide/using-warnings.rst
+++ b/docs/users_guide/using-warnings.rst
@@ -1881,6 +1881,20 @@ of ``-W(no-)*``.
Does nothing.
+.. ghc-flag:: -Wderiving-typeable
+ :shortdesc: warn when Typeable is derived
+ :type: dynamic
+ :reverse: -Wno-deriving-typeable
+ :category:
+
+ :since: 7.10
+
+ This flag warns when ``Typeable`` is listed in a deriving clause
+ or derived with :extension:`StandaloneDeriving`.
+
+ Since GHC 7.10, ``Typeable`` is automatically derived for all types.
+ Thus, deriving ``Typeable`` yourself is redundant.
+
If you're feeling really paranoid, the :ghc-flag:`-dcore-lint` option is a good choice.
It turns on heavyweight intra-pass sanity-checking within GHC. (It checks GHC's
sanity, not yours.)