Remove errShortString, cleanup error-related functions

This commit removes the errShortString field from the ErrMsg type,
allowing us to cleanup a lot of dynflag-dependent error functions, and
move them in a more specialised 'GHC.Driver.Errors' closer to the
driver, where they are actually used.

Metric Increase:
  T4801
  T9961

2 files changed, 8 insertions, 11 deletions

diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs
index 174055bd01..819740c341 100644
--- a/compiler/GHC/Tc/Module.hs
+++ b/compiler/GHC/Tc/Module.hs
@@ -208,7 +208,7 @@ tcRnModule hsc_env mod_sum save_rn_syntax
     hsc_src = ms_hsc_src mod_sum
     dflags = hsc_dflags hsc_env
     home_unit = hsc_home_unit hsc_env
-    err_msg = mkPlainErrMsg dflags loc $
+    err_msg = mkPlainErrMsg loc $
               text "Module does not have a RealSrcSpan:" <+> ppr this_mod
 
     pair :: (Module, SrcSpan)
@@ -3119,5 +3119,5 @@ mark_plugin_unsafe dflags = unless (gopt Opt_PluginTrustworthy dflags) $
   recordUnsafeInfer pluginUnsafe
   where
     unsafeText = "Use of plugins makes the module unsafe"
-    pluginUnsafe = unitBag ( mkPlainWarnMsg dflags noSrcSpan
+    pluginUnsafe = unitBag ( mkPlainWarnMsg noSrcSpan
                                    (Outputable.text unsafeText) )
diff --git a/compiler/GHC/Tc/Utils/Monad.hs b/compiler/GHC/Tc/Utils/Monad.hs
index 7056ba898b..48348ce7d7 100644
--- a/compiler/GHC/Tc/Utils/Monad.hs
+++ b/compiler/GHC/Tc/Utils/Monad.hs
@@ -994,21 +994,19 @@ discardWarnings thing_inside
 
 mkLongErrAt :: SrcSpan -> MsgDoc -> MsgDoc -> TcRn ErrMsg
 mkLongErrAt loc msg extra
-  = do { dflags <- getDynFlags ;
-         printer <- getPrintUnqualified ;
+  = do { printer <- getPrintUnqualified ;
          unit_state <- hsc_units <$> getTopEnv ;
          let msg' = pprWithUnitState unit_state msg in
-         return $ mkLongErrMsg dflags loc printer msg' extra }
+         return $ mkLongErrMsg loc printer msg' extra }
 
 mkErrDocAt :: SrcSpan -> ErrDoc -> TcRn ErrMsg
 mkErrDocAt loc errDoc
-  = do { dflags <- getDynFlags ;
-         printer <- getPrintUnqualified ;
+  = do { printer <- getPrintUnqualified ;
          unit_state <- hsc_units <$> getTopEnv ;
          let f = pprWithUnitState unit_state
              errDoc' = mapErrDoc f errDoc
          in
-         return $ mkErrDoc dflags loc printer errDoc' }
+         return $ mkErrDoc loc printer errDoc' }
 
 addLongErrAt :: SrcSpan -> MsgDoc -> MsgDoc -> TcRn ()
 addLongErrAt loc msg extra = mkLongErrAt loc msg extra >>= reportError
@@ -1515,9 +1513,8 @@ add_warn reason msg extra_info
 -- | Display a warning, with an optional flag, for a given location.
 add_warn_at :: WarnReason -> SrcSpan -> MsgDoc -> MsgDoc -> TcRn ()
 add_warn_at reason loc msg extra_info
-  = do { dflags <- getDynFlags ;
-         printer <- getPrintUnqualified ;
-         let { warn = mkLongWarnMsg dflags loc printer
+  = do { printer <- getPrintUnqualified ;
+         let { warn = mkLongWarnMsg loc printer
                                     msg extra_info } ;
          reportWarning reason warn }