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Skip generating foreign calls under ghcide, generate stubs instead #128

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Sep 29, 2023
Merged

Skip generating foreign calls under ghcide, generate stubs instead #128

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26 changes: 20 additions & 6 deletions inline-c/src/Language/C/Inline/FunPtr.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,9 @@ module Language.C.Inline.FunPtr
, uniqueFfiImportName
) where

import Data.Maybe (isJust)
import Foreign.Ptr (FunPtr)
import System.Environment (lookupEnv)
import qualified Language.Haskell.TH as TH
import qualified Language.Haskell.TH.Syntax as TH

Expand All @@ -27,9 +29,15 @@ import qualified Language.Haskell.TH.Syntax as TH
mkFunPtr :: TH.TypeQ -> TH.ExpQ
mkFunPtr hsTy = do
ffiImportName <- uniqueFfiImportName
dec <- TH.forImpD TH.CCall TH.Safe "wrapper" ffiImportName [t| $(hsTy) -> IO (FunPtr $(hsTy)) |]
TH.addTopDecls [dec]
TH.varE ffiImportName
-- See note [ghcide-support]
usingGhcide <- TH.runIO $ isJust <$> lookupEnv "__GHCIDE__"
if usingGhcide
then do
[e|error "inline-c: A 'usingGhcide' mkFunPtr stub was evaluated -- this should not happen" :: $(hsTy) -> IO (FunPtr $(hsTy)) |]
else do -- Actual foreign function call generation.
dec <- TH.forImpD TH.CCall TH.Safe "wrapper" ffiImportName [t| $(hsTy) -> IO (FunPtr $(hsTy)) |]
TH.addTopDecls [dec]
TH.varE ffiImportName

-- | @$('mkFunPtrFromName' 'foo)@, if @foo :: 'CDouble' -> 'IO'
-- 'CDouble'@, splices in an expression of type @'IO' ('FunPtr'
Expand All @@ -56,9 +64,15 @@ mkFunPtrFromName name = do
peekFunPtr :: TH.TypeQ -> TH.ExpQ
peekFunPtr hsTy = do
ffiImportName <- uniqueFfiImportName
dec <- TH.forImpD TH.CCall TH.Safe "dynamic" ffiImportName [t| FunPtr $(hsTy) -> $(hsTy) |]
TH.addTopDecls [dec]
TH.varE ffiImportName
usingGhcide <- TH.runIO $ isJust <$> lookupEnv "__GHCIDE__"
-- See note [ghcide-support]
if usingGhcide
then do
[e|error "inline-c: A 'usingGhcide' peekFunPtr stub was evaluated -- this should not happen" :: FunPtr $(hsTy) -> $(hsTy) |]
else do -- Actual foreign function call generation.
dec <- TH.forImpD TH.CCall TH.Safe "dynamic" ffiImportName [t| FunPtr $(hsTy) -> $(hsTy) |]
TH.addTopDecls [dec]
TH.varE ffiImportName

-- TODO absurdly, I need to 'newName' twice for things to work. I found
-- this hack in language-c-inline. Why is this?
Expand Down
25 changes: 18 additions & 7 deletions inline-c/src/Language/C/Inline/Internal.hs
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Expand Up @@ -64,12 +64,13 @@ import Control.Monad.State (evalStateT, StateT, get, put)
import Control.Monad.Trans.Class (lift)
import Data.Foldable (forM_)
import qualified Data.Map as Map
import Data.Maybe (fromMaybe)
import Data.Maybe (fromMaybe, isJust)
import Data.Traversable (for)
import Data.Typeable (Typeable, cast)
import qualified Language.Haskell.TH as TH
import qualified Language.Haskell.TH.Quote as TH
import qualified Language.Haskell.TH.Syntax as TH
import System.Environment (lookupEnv)
import System.IO.Unsafe (unsafePerformIO, unsafeDupablePerformIO)
import qualified Text.Parsec as Parsec
import qualified Text.Parsec.Pos as Parsec
Expand Down Expand Up @@ -298,12 +299,22 @@ inlineCode Code{..} = do
void $ emitVerbatim $ out $ directive ++ codeDefs
-- Create and add the FFI declaration.
ffiImportName <- uniqueFfiImportName
dec <- if codeFunPtr
then
TH.forImpD TH.CCall codeCallSafety ("&" ++ codeFunName) ffiImportName [t| FunPtr $(codeType) |]
else TH.forImpD TH.CCall codeCallSafety codeFunName ffiImportName codeType
TH.addTopDecls [dec]
TH.varE ffiImportName
-- Note [ghcide-support]
-- haskell-language-server / ghcide cannot handle code that use
-- `addForeignFile`/`addForeignSource` as we do here; it will result
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I understand that it doesn't work, but I think what should be fixed is the tool, not the code generation part.
I don't want to add a flag for the tools here.

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I think what should be fixed is the tool, not the code generation part.

@junjihashimoto What fix do you suggest? There's none known to me.

If you find it better, we can use an environemnt variable that has in the name that linking does not work in this environment instead of __GHCIDE__ specifically, so it covers all tools where linking as expected by inline-c does not work.

I don't want to add a flag for the tools here.

Usage of inline-c breaks HLS (which it does), everybody will carry this patch anyway.

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@junjihashimoto junjihashimoto Sep 29, 2023 •
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@nh2 One idea is creating a ghc plugin and adding a mechanism to set functions that don't work. The plugin generates dummy code for each function. It's a code generation problem, so I think we can solve a series of problems by the plugin.

-- in linker errors during TH evaluations, see:
-- <https://github.com/haskell/haskell-language-server/issues/365#issuecomment-976294466>
-- Thus for GHCIDE, simply generate a call to `error` instead of a call to a foreign import.
usingGhcide <- TH.runIO $ isJust <$> lookupEnv "__GHCIDE__"
if usingGhcide
then do
[e|error "inline-c: A 'usingGhcide' inlineCode stub was evaluated -- this should not happen" :: $(if codeFunPtr then [t| FunPtr $(codeType) |] else codeType) |]
else do -- Actual foreign function call generation.
dec <- if codeFunPtr
then TH.forImpD TH.CCall codeCallSafety ("&" ++ codeFunName) ffiImportName [t| FunPtr $(codeType) |]
else TH.forImpD TH.CCall codeCallSafety codeFunName ffiImportName codeType
TH.addTopDecls [dec]
TH.varE ffiImportName

uniqueCName :: Maybe String -> TH.Q String
uniqueCName mbPostfix = do
Expand Down