daml/bazel_tools/haskell_proto3_suite_deriving_defaults.patch

GHC 8.10 enables -Wderiving-defaults as part of -Wall.
It’s a useful warning so we want to keep it. However,
proto3-suite generates code that triggers this warning.
Now ideally, we would just switch proto3-suite over to
DerivingStrategies but unfortunately haskell-src, the library
used to generate the Haskell source, does not support that.
So instead, we disable the warning on a per file basis.
The warning only exists in GHC >= 8.10 so we cannot
upstream this atm.
diff --git a/src/Proto3/Suite/DotProto/Generate.hs b/src/Proto3/Suite/DotProto/Generate.hs
index ef16ba4..b62ee6b 100644
--- a/src/Proto3/Suite/DotProto/Generate.hs
+++ b/src/Proto3/Suite/DotProto/Generate.hs
@@ -128,6 +128,7 @@ renderHsModuleForDotProto extraInstanceFiles dotProto importCtxt = do
       {-# OPTIONS_GHC -fno-warn-name-shadowing       #-}
       {-# OPTIONS_GHC -fno-warn-unused-matches       #-}
       {-# OPTIONS_GHC -fno-warn-missing-export-lists #-}
+      {-# OPTIONS_GHC -Wno-deriving-defaults #-}
 
       -- | Generated by Haskell protocol buffer compiler. DO NOT EDIT!
     |]