Document DsOverflowedLiterals -> 97441 (closes #2)

Author: jhrcek

message-index/messages/GHC-97441/example1/after/OverflowedLiterals.hs

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+module Main where
+
+import Data.Word (Word8)
+
+main :: IO ()
+main = do
+    -- Word8 can represent values in range (0,255)
+    -- prints 255
+    print (255 :: Word8)
+
+    -- Int can represent values in range (-9223372036854775808,9223372036854775807)
+    -- prints 9223372036854775807
+    print (9223372036854775807 :: Int)

message-index/messages/GHC-97441/example1/before/OverflowedLiterals.hs

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+module Main where
+
+import Data.Word (Word8)
+
+main :: IO ()
+main = do
+    -- Word8 can represent values in range (0,255)
+    -- prints 2 due to overflow
+    print (258 :: Word8)
+    --       ^ value is 3 larger than maxBound so it will wrap around 0 -> 1 -> 2
+
+    -- Int can represent values in range (-9223372036854775808,9223372036854775807)
+    -- prints -9223372036854775799 due to overflow
+    print (9223372036854775817 :: Int)
+    --                      ^ value is 10 larger than maxBound

message-index/messages/GHC-97441/example1/index.md

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+---
+title: Overflowed Literal
+---
+
+## Error Message
+```
+before/OverflowedLiterals.hs:9:12: warning: [GHC-97441] [-Woverflowed-literals]
+    Literal 258 is out of the Word8 range 0..255
+  |
+9 |     print (258 :: Word8)
+  |            ^^^
+
+before/OverflowedLiterals.hs:14:12: warning: [GHC-97441] [-Woverflowed-literals]
+    Literal 9223372036854775817 is out of the Int range -9223372036854775808..9223372036854775807
+   |
+14 |     print (9223372036854775817 :: Int) 
+   |            ^^^^^^^^^^^^^^^^^^^
+
+```

message-index/messages/GHC-97441/index.md

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+---
+title: Overflowed Literal
+summary: Literal overflowing range of supported values
+severity: warning
+introduced: 9.6.1
+flag: -Woverflowed-literals
+---
+
+Warning emitted if a literal (constant value in the source code) will overflow.
+This doesn't cause error at runtime, but might cause confusion because overflowed value might be different than what you expect.
+
+To fix the warning you can:
+
+- Use different value for the literal so that it fits within the range supported by its type
+- Use different type, which is capable of representing the value