Apply CLASH_MULTIPLE_HIDDEN to clash-prelude:doctests

Current doctest(-parallel) can't pickup such defines automatically, so 
we have to do it manually.

And also define CLASH_OPAQUE, to prevent a ton of warnings.

Author: leonschoorl

cabal.project

@@ -16,7 +16,7 @@ write-ghc-environment-files: always
 -- index state, to go along with the cabal.project.freeze file. update the index
 -- state by running `cabal update` twice and looking at the index state it
 -- displays to you (as the second update will be a no-op)
-index-state: 2023-09-12T05:36:44Z
+index-state: 2023-10-18T12:11:41Z
 
 -- For some reason the `clash-testsuite` executable fails to run without
 -- this, as it cannot find the related library...
@@ -81,4 +81,3 @@ package recursion-schemes
 
 package regex-tdfa
     optimization: 2
-

clash-prelude/clash-prelude.cabal

@@ -385,12 +385,15 @@ test-suite doctests
     build-depends:
       base,
       clash-prelude,
-      doctest-parallel >= 0.2 && < 0.4,
+      doctest-parallel >= 0.3.1 && < 0.4,
       filepath
 
   if flag(workaround-ghc-mmap-crash)
     ghc-options:    -with-rtsopts=-xm20000000
 
+  if flag(multiple-hidden)
+    CPP-Options: -DCLASH_MULTIPLE_HIDDEN
+
 
 test-suite unittests
   import:           common-options

clash-prelude/tests/doctests.hs

@@ -1,7 +1,21 @@
+{-# LANGUAGE CPP #-}
 module Main where
 
-import System.Environment (getArgs)
 import Test.DocTest (mainFromCabal)
+import System.Environment (getArgs)
 
 main :: IO ()
-main = mainFromCabal "clash-prelude" =<< getArgs
+main = mainFromCabal "clash-prelude" =<< fmap (extraArgs ++) getArgs
+
+extraArgs :: [String]
+extraArgs = map ("--ghc-arg=" ++)
+  [
+#if __GLASGOW_HASKELL__ >= 904
+    "-DCLASH_OPAQUE=OPAQUE"
+#else
+    "-DCLASH_OPAQUE=NOINLINE"
+#endif
+#ifdef CLASH_MULTIPLE_HIDDEN
+  , "-DCLASH_MULTIPLE_HIDDEN"
+#endif
+  ]