This package does not build with GHC 9.4.8.

[kindaro]

what I do

% git remote -v
origin	https://github.com/pxqr/base32-bytestring.git (fetch)
origin	https://github.com/pxqr/base32-bytestring.git (push)
% git rev-parse @
3a6fe39aa734fd053baababdc8afa413999c8cd1
% ghc --version
The Glorious Glasgow Haskell Compilation System, version 9.4.8
% cabal build
Build profile: -w ghc-9.4.8 -O1
In order, the following will be built (use -v for more details):
 - base32-bytestring-0.2.1.0 (lib) (first run)
Preprocessing library for base32-bytestring-0.2.1.0..
Building library for base32-bytestring-0.2.1.0..
[1 of 3] Compiling Data.ByteString.Base32.Internal ( src/Data/ByteString/Base32/Internal.hs, /tmp/base32-bytestring/dist-newstyle/build/x86_64-linux/ghc-9.4.8/base32-bytestring-0.2.1.0/build/Data/ByteString/Base32/Internal.o, /tmp/base32-bytestring/dist-newstyle/build/x86_64-linux/ghc-9.4.8/base32-bytestring-0.2.1.0/build/Data/ByteString/Base32/Internal.dyn_o )

src/Data/ByteString/Base32/Internal.hs:73:1: error:
    Parse error in pattern: unpack5Ptr In a function binding for the ‘@’ operator.
                            Perhaps you meant an as-pattern, which must not be surrounded by whitespace
   |
73 | unpack5Ptr !tbl bs @ (PS fptr off sz) =
   | ^^^^^^^^^^^^^^^^^^
Error: cabal: Failed to build base32-bytestring-0.2.1.0.

what should happen

Running cabal build should build the package.

discussion

The reason for this error is that the parsing of @ has become white space sensitive, I think since the proposal ghc-proposals/ghc-proposals#229, so in this case white space about the @ needs to be cut away.

[kindaro]

After removing the white space about all @ characters and replacing inlinePerformIO with unsafePerformIO, I have this package build. Here is the patch:

diff --git a/src/Data/ByteString/Base32/Internal.hs b/src/Data/ByteString/Base32/Internal.hs
index aa7c5b3..29a9720 100644
--- a/src/Data/ByteString/Base32/Internal.hs
+++ b/src/Data/ByteString/Base32/Internal.hs
@@ -70,7 +70,7 @@ padCeilN !n !x
 -----------------------------------------------------------------------}

 unpack5Ptr :: Ptr Word8 -> ByteString -> ByteString
-unpack5Ptr !tbl bs @ (PS fptr off sz) =
+unpack5Ptr !tbl bs@(PS fptr off sz) =
   unsafePerformIO $ do
     let unpackedSize = dstSize $ BS.length bs
     BS.create unpackedSize $ \ dst -> do
@@ -164,7 +164,7 @@ cleanup io = unsafePerformIO $
     handler (ErrorCall msg) = return (Left msg)

 pack5Ptr :: Ptr Word5 -> ByteString -> Result ByteString
-pack5Ptr !tbl bs @ (PS fptr off sz) =
+pack5Ptr !tbl bs@(PS fptr off sz) =
   cleanup $ do
     let packedSize = dstSize $ BS.length bs
     BS.createAndTrim packedSize $ \ dst -> do
@@ -176,7 +176,7 @@ pack5Ptr !tbl bs @ (PS fptr off sz) =
     lookupTable ix
         | x == invIx = error $ show (w2c ix) ++ " is not base32 character"
         | otherwise  = x
-      where x = inlinePerformIO (peekByteOff tbl (fromIntegral ix))
+      where x = unsafePerformIO (peekByteOff tbl (fromIntegral ix))
     {-# INLINE lookupTable #-}

     dstSize x = d + if m == 0 then 0 else 1
@@ -248,10 +248,10 @@ pack5 (PS fptr off len) bs

 isInAlphabet :: Ptr Word5 -> Word8 -> Bool
 isInAlphabet !tbl !ix =
-  inlinePerformIO (peekByteOff tbl (fromIntegral ix)) /= invIx
+  unsafePerformIO (peekByteOff tbl (fromIntegral ix)) /= invIx

 pack5Lenient :: DecTable -> ByteString -> Either String ByteString
-pack5Lenient tbl @ (PS fptr _ _) bs =
+pack5Lenient tbl@(PS fptr _ _) bs =
   unsafePerformIO $ do
     withForeignPtr fptr $ \ !tbl_ptr -> do
       return $! pack5 tbl $ BS.filter (isInAlphabet tbl_ptr) bs

I have not checked if the package works as it should though.