From 1f6f517ac7beaa84f51f5a68c6a0f038e7bc66af Mon Sep 17 00:00:00 2001
From: Zubin Duggal <zubin.duggal@gmail.com>
Date: Wed, 6 Dec 2023 11:35:56 +0530
Subject: [PATCH] session-loader: Set working directory on GHC 9.4+

We set the working directory appropriately so that TH code can access it and
read files relative to the root of the current component.

Fixes #481
---
 ghcide/session-loader/Development/IDE/Session.hs |  3 ++-
 ghcide/src/Development/IDE/GHC/Compat/Env.hs     |  9 ++++++++-
 ghcide/test/data/working-dir/a/A.hs              | 11 +++++++++++
 ghcide/test/data/working-dir/a/B.hs              |  6 ++++++
 ghcide/test/data/working-dir/a/a.cabal           | 11 +++++++++++
 ghcide/test/data/working-dir/a/wdtest            |  1 +
 ghcide/test/data/working-dir/cabal.project       |  1 +
 ghcide/test/data/working-dir/hie.yaml            |  2 ++
 8 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 ghcide/test/data/working-dir/a/A.hs
 create mode 100644 ghcide/test/data/working-dir/a/B.hs
 create mode 100644 ghcide/test/data/working-dir/a/a.cabal
 create mode 100644 ghcide/test/data/working-dir/a/wdtest
 create mode 100644 ghcide/test/data/working-dir/cabal.project
 create mode 100644 ghcide/test/data/working-dir/hie.yaml

diff --git a/ghcide/session-loader/Development/IDE/Session.hs b/ghcide/session-loader/Development/IDE/Session.hs
index 42615de78a4..9ed864bed47 100644
--- a/ghcide/session-loader/Development/IDE/Session.hs
+++ b/ghcide/session-loader/Development/IDE/Session.hs
@@ -1115,6 +1115,7 @@ setOptions cfp (ComponentOptions theOpts compRoot _) dflags = do
               Nothing -> compRoot
               Just wdir -> compRoot </> wdir
         let dflags''' =
+              setWorkingDirectory root $
               disableWarningsAsErrors $
               -- disabled, generated directly by ghcide instead
               flip gopt_unset Opt_WriteInterface $
@@ -1125,7 +1126,7 @@ setOptions cfp (ComponentOptions theOpts compRoot _) dflags = do
               setBytecodeLinkerOptions $
               disableOptimisation $
               Compat.setUpTypedHoles $
-              makeDynFlagsAbsolute compRoot
+              makeDynFlagsAbsolute root
               dflags''
         -- initPackages parses the -package flags and
         -- sets up the visibility for each component.
diff --git a/ghcide/src/Development/IDE/GHC/Compat/Env.hs b/ghcide/src/Development/IDE/GHC/Compat/Env.hs
index 66d135737c7..5466d5fc22e 100644
--- a/ghcide/src/Development/IDE/GHC/Compat/Env.hs
+++ b/ghcide/src/Development/IDE/GHC/Compat/Env.hs
@@ -55,7 +55,8 @@ module Development.IDE.GHC.Compat.Env (
     setBackend,
     ghciBackend,
     Development.IDE.GHC.Compat.Env.platformDefaultBackend,
-    workingDirectory
+    workingDirectory,
+    setWorkingDirectory,
     ) where
 
 import           GHC                 (setInteractiveDynFlags)
@@ -91,6 +92,12 @@ hsc_EPS = Env.hsc_unit_env
 #if !MIN_VERSION_ghc(9,3,0)
 workingDirectory :: a -> Maybe b
 workingDirectory _ = Nothing
+
+setWorkingDirectory :: FilePath -> DynFlags -> DynFlags
+setWorkingDirectory = const id
+#else
+setWorkingDirectory :: FilePath -> DynFlags -> DynFlags
+setWorkingDirectory p d = d { workingDirectory =  Just p }
 #endif
 
 setHomeUnitId_ :: UnitId -> DynFlags -> DynFlags
diff --git a/ghcide/test/data/working-dir/a/A.hs b/ghcide/test/data/working-dir/a/A.hs
new file mode 100644
index 00000000000..5b4f28ba40a
--- /dev/null
+++ b/ghcide/test/data/working-dir/a/A.hs
@@ -0,0 +1,11 @@
+{-# LANGUAGE TemplateHaskell #-}
+module A(th_a) where
+
+import Language.Haskell.TH
+import Language.Haskell.TH.Syntax
+import Control.Monad.IO.Class
+
+th_a :: DecsQ
+th_a = do
+  str <- makeRelativeToProject "wdtest" >>= liftIO . readFile
+  [d| a = $(lift str) |]
diff --git a/ghcide/test/data/working-dir/a/B.hs b/ghcide/test/data/working-dir/a/B.hs
new file mode 100644
index 00000000000..8563bb08751
--- /dev/null
+++ b/ghcide/test/data/working-dir/a/B.hs
@@ -0,0 +1,6 @@
+{-# LANGUAGE TemplateHaskell #-}
+module B() where
+
+import A
+
+$th_a
diff --git a/ghcide/test/data/working-dir/a/a.cabal b/ghcide/test/data/working-dir/a/a.cabal
new file mode 100644
index 00000000000..1b92d218498
--- /dev/null
+++ b/ghcide/test/data/working-dir/a/a.cabal
@@ -0,0 +1,11 @@
+name: a
+version: 1.0.0
+build-type: Simple
+cabal-version: >= 1.2
+extra-source-files: wdtest
+
+library
+  build-depends: base, template-haskell
+  exposed-modules: A B
+  ghc-options: -Wmissing-signatures
+  hs-source-dirs: .
diff --git a/ghcide/test/data/working-dir/a/wdtest b/ghcide/test/data/working-dir/a/wdtest
new file mode 100644
index 00000000000..9daeafb9864
--- /dev/null
+++ b/ghcide/test/data/working-dir/a/wdtest
@@ -0,0 +1 @@
+test
diff --git a/ghcide/test/data/working-dir/cabal.project b/ghcide/test/data/working-dir/cabal.project
new file mode 100644
index 00000000000..80dfe76da50
--- /dev/null
+++ b/ghcide/test/data/working-dir/cabal.project
@@ -0,0 +1 @@
+packages: a
diff --git a/ghcide/test/data/working-dir/hie.yaml b/ghcide/test/data/working-dir/hie.yaml
new file mode 100644
index 00000000000..04cd24395e4
--- /dev/null
+++ b/ghcide/test/data/working-dir/hie.yaml
@@ -0,0 +1,2 @@
+cradle:
+  cabal: