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Diffstat (limited to 'compiler/GHC/Runtime/Loader.hs')
| -rw-r--r-- | compiler/GHC/Runtime/Loader.hs | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/compiler/GHC/Runtime/Loader.hs b/compiler/GHC/Runtime/Loader.hs index 3349ed0020..5617376f60 100644 --- a/compiler/GHC/Runtime/Loader.hs +++ b/compiler/GHC/Runtime/Loader.hs @@ -76,6 +76,29 @@ import Data.List (unzip4) import GHC.Iface.Errors.Ppr import GHC.Driver.Monad +{- Note [Timing of plugin initialization] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Plugins needs to be initialised as soon as possible in the pipeline. This is because +driver plugins are executed immediately after being loaded, which can modify anything +in the HscEnv, including the logger and DynFlags (for example #21279). For example, +in ghc/Main.hs the logger is used almost immediately after the session has been initialised +and so if a user overwrites the logger expecting all output to go there then unless +the plugins are initialised before that point then unexpected things will happen. + +We initialise plugins in ghc/Main.hs for the main ghc executable. + +When people are using the GHC API, they also need to initialise plugins +at the highest level possible for things to work as expected. We keep +some defensive calls to plugin initialisation in functions like `load'` and `oneshot` +to catch cases where API users have not initialised their own plugins. + +In addition to this, there needs to be an initialisation call for each module +just in case the user has enabled a plugin just for that module using OPTIONS_GHC +pragma. + +-} + -- | Initialise plugins specified by the current DynFlags and update the session. initializeSessionPlugins :: GhcMonad m => m () initializeSessionPlugins = getSession >>= liftIO . initializePlugins >>= setSession |