Add GHC-17335

Author: hsyl20

message-index/messages/GHC-17335/dsIncompleteRecSel/after/DsIncompleteRecSel.hs

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+module DsIncompleteRecSel where
+
+data T = T1 | T2 {x :: Bool}
+
+f T1 = True -- handle the T1 case
+f a = x a

message-index/messages/GHC-17335/dsIncompleteRecSel/before/DsIncompleteRecSel.hs

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+module DsIncompleteRecSel where
+
+data T = T1 | T2 {x :: Bool}
+
+f a = x a

message-index/messages/GHC-17335/dsIncompleteRecSel/index.md

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+---
+title: Incomplete record selector application
+---

message-index/messages/GHC-17335/index.md

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+---
+title: Incomplete record selector application
+summary: A record selector application may not be successful
+severity: warning
+flag: -Wincomplete-record-selectors
+introduced: 9.10.1
+---
+
+This warning is triggered when GHC is not certain whether a record selector
+application will be successful. This happens when a record selector is not
+defined for all constructors of a data type (a.k.a. partial record field
+selector) and it is applied to a value whose data constructor can't be proved by
+GHC to be one for which the selector is defined.