Fix ambiguous data files on duplicate idir

changelog/2026-02-08T22_02_38+01_00_fix_3141

@@ -0,0 +1 @@
+FIXED: Clash will no longer error if it finds the same data file more than once due to duplicate `-i` flags [#3141](https://github.com/clash-lang/clash-compiler/issues/3141)

clash-lib/src/Clash/Netlist/BlackBox/Util.hs

@@ -46,6 +46,7 @@ import           Control.Monad.State             (State, StateT (..), lift, gets
 import           Data.Bitraversable              (bitraverse)
 import           Data.Bool                       (bool)
 import           Data.Coerce                     (coerce)
+import           Data.Containers.ListUtils       (nubOrd)
 import           Data.Foldable                   (foldrM)
 import           Data.Hashable                   (Hashable (..))
 import qualified Data.HashMap.Strict             as HashMap
@@ -332,7 +333,7 @@ canonicalizeDataFilePath idirs toCanonicalize
       (canonicalizePath toCanonicalize)
       (error [I.i|Could not find data file #{show toCanonicalize}. Does it exist?|])
   | otherwise = unsafePerformIO $ do
-      let candidates = map (</> toCanonicalize) idirs
+      let candidates = map (</> toCanonicalize) (nubOrd idirs)
       found <- filterM doesFileExist candidates
       case found of
         [] -> error [I.i|

tests/Main.hs

@@ -668,6 +668,7 @@ runClashTest = defaultMain
            in runTest "T3021" _opts
         , let _opts = def { hdlTargets = [VHDL], hdlLoad = [], hdlSim = []}
            in runTest "T3084" _opts
+        , runTest "T3141" def{hdlSim=[], hdlLoad=[], clashFlags=["-itests/shouldwork/Issues/T3141", "-itests/shouldwork/Issues/T3141"]}
         ] <>
         if compiledWith == Cabal then
           -- This tests fails without environment files present, which are only

tests/shouldwork/Issues/T3141.hs

@@ -0,0 +1,11 @@
+module T3141 where
+
+import Clash.Explicit.Prelude
+
+topEntity ::
+  Clock System ->
+  Enable System ->
+  Signal System (Unsigned 4) ->
+  Signal System (Maybe (Unsigned 4, BitVector 8)) ->
+  Signal System (BitVector 8)
+topEntity clk ena = blockRamFile clk ena d16 "T3141.mem"