WW: Use module name rather than filename for absent error messages

WwOpts in WorkWrap.Utils initialised the wo_output_file field with the
result of outputFile dflags. This is misguided because outputFile is
only set when -o is specified, which is barely ever (and never in --make
mode).

It seems this is
just used to add more context to an error message, a more appropriate
thing to use I think would be a module name.

Fixes #20438

3 files changed, 12 insertions, 11 deletions

diff --git a/compiler/GHC/Core/Opt/Pipeline.hs b/compiler/GHC/Core/Opt/Pipeline.hs
index ad7905ee27..18ac910d15 100644
--- a/compiler/GHC/Core/Opt/Pipeline.hs
+++ b/compiler/GHC/Core/Opt/Pipeline.hs
@@ -514,7 +514,7 @@ doCorePass pass guts = do
                                  updateBindsM (liftIO . cprAnalProgram logger fam_envs)
 
     CoreDoWorkerWrapper       -> {-# SCC "WorkWrap" #-}
-                                 updateBinds (wwTopBinds dflags fam_envs us)
+                                 updateBinds (wwTopBinds (mg_module guts) dflags fam_envs us)
 
     CoreDoSpecialising        -> {-# SCC "Specialise" #-}
                                  specProgram guts
diff --git a/compiler/GHC/Core/Opt/WorkWrap.hs b/compiler/GHC/Core/Opt/WorkWrap.hs
index 2c204795c9..976dcd5fe5 100644
--- a/compiler/GHC/Core/Opt/WorkWrap.hs
+++ b/compiler/GHC/Core/Opt/WorkWrap.hs
@@ -37,6 +37,7 @@ import GHC.Utils.Panic
 import GHC.Utils.Panic.Plain
 import GHC.Utils.Monad
 import GHC.Utils.Trace
+import GHC.Unit.Types
 
 {-
 We take Core bindings whose binders have:
@@ -66,14 +67,14 @@ info for exported values).
 \end{enumerate}
 -}
 
-wwTopBinds :: DynFlags -> FamInstEnvs -> UniqSupply -> CoreProgram -> CoreProgram
+wwTopBinds :: Module -> DynFlags -> FamInstEnvs -> UniqSupply -> CoreProgram -> CoreProgram
 
-wwTopBinds dflags fam_envs us top_binds
+wwTopBinds this_mod dflags fam_envs us top_binds
   = initUs_ us $ do
     top_binds' <- mapM (wwBind ww_opts) top_binds
     return (concat top_binds')
   where
-    ww_opts = initWwOpts dflags fam_envs
+    ww_opts = initWwOpts this_mod dflags fam_envs
 
 {-
 ************************************************************************
diff --git a/compiler/GHC/Core/Opt/WorkWrap/Utils.hs b/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
index 50200d18b0..df3608fe7d 100644
--- a/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
+++ b/compiler/GHC/Core/Opt/WorkWrap/Utils.hs
@@ -64,6 +64,7 @@ import Control.Monad ( zipWithM )
 import Data.List ( unzip4 )
 
 import GHC.Types.RepType
+import GHC.Unit.Types
 
 {-
 ************************************************************************
@@ -141,17 +142,18 @@ data WwOpts
   , wo_cpr_anal          :: !Bool
   , wo_fun_to_thunk      :: !Bool
   , wo_max_worker_args   :: !Int
-  , wo_output_file       :: Maybe String
+  -- Used for absent argument error message
+  , wo_module            :: !Module
   }
 
-initWwOpts :: DynFlags -> FamInstEnvs -> WwOpts
-initWwOpts dflags fam_envs = MkWwOpts
+initWwOpts :: Module -> DynFlags -> FamInstEnvs -> WwOpts
+initWwOpts this_mod dflags fam_envs = MkWwOpts
   { wo_fam_envs          = fam_envs
   , wo_simple_opts       = initSimpleOpts dflags
   , wo_cpr_anal          = gopt Opt_CprAnal dflags
   , wo_fun_to_thunk      = gopt Opt_FunToThunk dflags
   , wo_max_worker_args   = maxWorkerArgs dflags
-  , wo_output_file       = outputFile dflags
+  , wo_module            = this_mod
   }
 
 type WwResult
@@ -1003,9 +1005,7 @@ mkAbsentFiller opts arg
               -- will have different lengths and hence different costs for
               -- the inliner leading to different inlining.
               -- See also Note [Unique Determinism] in GHC.Types.Unique
-    file_msg = case wo_output_file opts of
-                 Nothing -> empty
-                 Just f  -> text "In output file " <+> quotes (text f)
+    file_msg = text "In module" <+> quotes (ppr $ wo_module opts)
 
 {- Note [Worker/wrapper for Strictness and Absence]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~