Warn on use of unsafe decodeUtf8

Author: michaelpj

data/hlint.yaml

@@ -51,6 +51,12 @@
     - import Data.Attoparsec.Text
     - import Data.Attoparsec.ByteString
 
+- package:
+    name: text
+    modules:
+    - import Data.Text
+    - import Data.Text.Encoding
+
 - package:
     name: codeworld-api
     modules:
@@ -869,6 +875,14 @@
     - warn: {lhs: Data.Attoparsec.Text.option Nothing (Just <$> p),       rhs: optional p}
     - warn: {lhs: Data.Attoparsec.ByteString.option Nothing (Just <$> p), rhs: optional p}
 
+- group:
+    name: text
+    enabled: true
+    imports:
+    - package text
+    rules:
+    - warn: {lhs: decodeUtf8, rhs: decodeUtf8', name: Avoid decodeUtf8}
+
 - group:
     name: generalise
     enabled: false
@@ -1235,6 +1249,10 @@
 # issue1183 = (a >= 'a') && (a <= 'z') -- isAsciiLower a
 # issue1218 = uncurry (zipWith g) $ (a, b) -- zipWith g a b
 
+# import Data.Text
+# import Data.Text.Encoding
+# yes = decodeUtf8 -- decodeUtf8'
+
 # import Language.Haskell.TH\
 # yes = varE 'foo -- [|foo|]
 # import Prelude \

hints.md

@@ -11921,4 +11921,20 @@ optional p
 </td>
 <td>Warning</td>
 </tr>
+<tr>
+<td>Avoid decodeUtf8</td>
+<td>
+LHS:
+<code>
+Data.Text.Encoding.decodeUtf8
+</code>
+<br>
+RHS:
+<code>
+Data.Text.Encoding.decodeUtf8'
+</code>
+<br>
+</td>
+<td>Warning</td>
+</tr>
 </table>