Track changes to setup-config #5578

Author: snoyberg

ChangeLog.md

@@ -34,6 +34,8 @@ Bug fixes:
 * `stack setup` will look in sandboxed directories for executables, not
   relying on `findExecutables. See
   [GHC issue 20074](https://gitlab.haskell.org/ghc/ghc/-/issues/20074)
+* Track changes to `setup-config` properly to avoid reconfiguring on every change.
+  See [#5578](https://github.com/commercialhaskell/stack/issues/5578)
 
 ## v2.7.1
 

src/Stack/Build/Cache.hs

@@ -21,6 +21,7 @@ module Stack.Build.Cache
     , writeBuildCache
     , writeConfigCache
     , writeCabalMod
+    , writeSetupConfigMod
     , TestStatus (..)
     , setTestStatus
     , getTestStatus
@@ -182,6 +183,20 @@ writeCabalMod dir x = do
     writeBinaryFileAtomic fp "Just used for its modification time"
     liftIO $ setFileTimes (toFilePath fp) x x
 
+-- | See 'tryGetSetupConfigMod'
+writeSetupConfigMod
+  :: HasEnvConfig env
+  => Path Abs Dir
+  -> Maybe CTime
+  -> RIO env ()
+writeSetupConfigMod dir Nothing = do
+    fp <- configSetupConfigMod dir
+    ignoringAbsence $ removeFile fp
+writeSetupConfigMod dir (Just x) = do
+    fp <- configSetupConfigMod dir
+    writeBinaryFileAtomic fp "Just used for its modification time"
+    liftIO $ setFileTimes (toFilePath fp) x x
+
 -- | Delete the caches for the project.
 deleteCaches :: HasEnvConfig env => Path Abs Dir -> RIO env ()
 deleteCaches dir

src/Stack/Build/Execute.hs

@@ -845,8 +845,10 @@ ensureConfig :: HasEnvConfig env
 ensureConfig newConfigCache pkgDir ExecuteEnv {..} announce cabal cabalfp task = do
     newCabalMod <- liftIO $ modificationTime <$> getFileStatus (toFilePath cabalfp)
     setupConfigfp <- setupConfigFromDir pkgDir
-    newSetupConfigMod <- liftIO $ either (const Nothing) (Just . modificationTime) <$>
-      tryJust (guard . isDoesNotExistError) (getFileStatus (toFilePath setupConfigfp))
+    let getNewSetupConfigMod =
+          liftIO $ either (const Nothing) (Just . modificationTime) <$>
+          tryJust (guard . isDoesNotExistError) (getFileStatus (toFilePath setupConfigfp))
+    newSetupConfigMod <- getNewSetupConfigMod
     -- See https://github.com/commercialhaskell/stack/issues/3554
     taskAnyMissingHack <- view $ actualCompilerVersionL.to getGhcVersion.to (< mkVersion [8, 4])
     needConfig <-
@@ -905,6 +907,11 @@ ensureConfig newConfigCache pkgDir ExecuteEnv {..} announce cabal cabalfp task =
             TTLocalMutable{} -> writeConfigCache pkgDir newConfigCache
             TTRemotePackage{} -> return ()
         writeCabalMod pkgDir newCabalMod
+        -- This file gets updated one more time by the configure step, so get
+        -- the most recent value. We could instead change our logic above to
+        -- check if our config mod file is newer than the file above, but this
+        -- seems reasonable too.
+        getNewSetupConfigMod >>= writeSetupConfigMod pkgDir
 
     return needConfig
   where