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Diffstat (limited to 'docs/users_guide/using-warnings.rst')
| -rw-r--r-- | docs/users_guide/using-warnings.rst | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/docs/users_guide/using-warnings.rst b/docs/users_guide/using-warnings.rst index 7c288d3767..2c70006a7c 100644 --- a/docs/users_guide/using-warnings.rst +++ b/docs/users_guide/using-warnings.rst @@ -2057,10 +2057,13 @@ of ``-W(no-)*``. :since: 8.4 - The option :ghc-flag:`-Wpartial-fields` warns about record fields that could - fail when accessed via a lacking constructor. The function ``f`` below will - fail when applied to ``Bar``, so the compiler will emit a warning at its - definition when :ghc-flag:`-Wpartial-fields` is enabled. + The option :ghc-flag:`-Wpartial-fields` warns about a record field + `f` that is defined in some, but not all, the contructors of a + data type, because `f`'s record selector function may fail. For + exampe, the record selector function `f`, defined in the `Foo` + constructor record below, will fail when applied to ``Bar``, so + the compiler will emit a warning at its definition when + :ghc-flag:`-Wpartial-fields` is enabled. The warning is suppressed if the field name begins with an underscore. :: |