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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2013-01-02 11:57:00 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2013-01-02 11:57:00 +0000 |
| commit | 5a6a223f855538112ec9d089425e34853fb3542b (patch) | |
| tree | dace13f28eddfe68fb5c16bfe6d46c7a9494a018 /docs | |
| parent | 302172f4959b92fa668db6b460921e710bdf6655 (diff) | |
| download | haskell-5a6a223f855538112ec9d089425e34853fb3542b.tar.gz | |
Add flag -fwarn-duplicate-constraints
This fixes Trac #7541, and is on by default.
Use -fno-warn-duplicate-constraints to switch it off.
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/flags.xml | 7 | ||||
| -rw-r--r-- | docs/users_guide/using.xml | 19 |
2 files changed, 26 insertions, 0 deletions
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml index 2103260671..e084315586 100644 --- a/docs/users_guide/flags.xml +++ b/docs/users_guide/flags.xml @@ -1236,6 +1236,13 @@ </row> <row> + <entry><option>-fwarn-duplicate-constraints</option></entry> + <entry>warn when a constraint appears duplicated in a type signature</entry> + <entry>dynamic</entry> + <entry><option>-fno-warn-duplicate-constraints</option></entry> + </row> + + <row> <entry><option>-fwarn-duplicate-exports</option></entry> <entry>warn when an entity is exported multiple times</entry> <entry>dynamic</entry> diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml index 292f4fe1c0..adc3694320 100644 --- a/docs/users_guide/using.xml +++ b/docs/users_guide/using.xml @@ -950,6 +950,7 @@ test.hs:(5,4)-(6,7): <option>-fwarn-overlapping-patterns</option>, <option>-fwarn-warnings-deprecations</option>, <option>-fwarn-deprecated-flags</option>, + <option>-fwarn-duplicate-constraints</option>, <option>-fwarn-duplicate-exports</option>, <option>-fwarn-missing-fields</option>, <option>-fwarn-missing-methods</option>, @@ -1195,6 +1196,24 @@ foreign import "&f" f :: FunPtr t </varlistentry> <varlistentry> + <term><option>-fwarn-duplicate-constraints</option>:</term> + <listitem> + <indexterm><primary><option>-fwarn-duplicate-constraints</option></primary></indexterm> + <indexterm><primary>duplicate constraints, warning</primary></indexterm> + + <para>Have the compiler warn about duplicate constraints in a type signature. For + example + <programlisting> + f :: (Eq a, Show a, Eq a) => a -> a + </programlisting> + The warning will indicate the duplicated <literal>Eq a</literal> constraint. + </para> + + <para>This option is on by default.</para> + </listitem> + </varlistentry> + + <varlistentry> <term><option>-fwarn-duplicate-exports</option>:</term> <listitem> <indexterm><primary><option>-fwarn-duplicate-exports</option></primary></indexterm> |