Driver Rework Patch

This patch comprises of four different but closely related ideas. The
net result is fixing a large number of open issues with the driver
whilst making it simpler to understand.

1. Use the hash of the source file to determine whether the source file
has changed or not. This makes the recompilation checking more robust to
modern build systems which are liable to copy files around changing
their modification times.

2. Remove the concept of a "stable module", a stable module was one
where the object file was older than the source file, and all transitive
dependencies were also stable. Now we don't rely on the modification
time of the source file, the notion of stability is moot.

3. Fix TH/plugin recompilation after the removal of stable modules. The
TH recompilation check used to rely on stable modules. Now there is a
uniform and simple way, we directly track the linkables which were
loaded into the interpreter whilst compiling a module. This is an
over-approximation but more robust wrt package dependencies changing.

4. Fix recompilation checking for dynamic object files. Now we actually
check if the dynamic object file exists when compiling with -dynamic-too

Fixes #19774 #19771 #19758 #17434 #11556 #9121 #8211 #16495 #7277 #16093

2 files changed, 3 insertions, 2 deletions

diff --git a/utils/check-exact/Main.hs b/utils/check-exact/Main.hs
index 63eabff460..b67efa2039 100644
--- a/utils/check-exact/Main.hs
+++ b/utils/check-exact/Main.hs
@@ -33,6 +33,7 @@ import GHC.Parser.Lexer
 import GHC.Data.FastString
 import GHC.Types.SrcLoc
 
+
 -- ---------------------------------------------------------------------
 
 _tt :: IO ()
@@ -346,7 +347,7 @@ parseOneFile libdir fileName =
          let dflags2 = dflags `gopt_set` Opt_KeepRawTokenStream
          _ <- setSessionDynFlags dflags2
          hsc_env <- getSession
-         emodSum <- liftIO $ summariseFile hsc_env [] fileName Nothing True Nothing
+         emodSum <- liftIO $ summariseFile hsc_env [] fileName Nothing Nothing
          case emsModSummary <$> emodSum of
            Left _err -> error "parseOneFile"
            Right modSum -> do
diff --git a/utils/check-ppr/Main.hs b/utils/check-ppr/Main.hs
index 80828874f6..d064431ec4 100644
--- a/utils/check-ppr/Main.hs
+++ b/utils/check-ppr/Main.hs
@@ -85,7 +85,7 @@ parseOneFile libdir fileName = do
          let dflags2 = dflags `gopt_set` Opt_KeepRawTokenStream
          _ <- setSessionDynFlags dflags2
          hsc_env <- getSession
-         ms <- liftIO $ summariseFile hsc_env [] fileName Nothing True Nothing
+         ms <- liftIO $ summariseFile hsc_env [] fileName Nothing Nothing
          case ms of
            Left _err -> error "parseOneFile"
            Right ems -> parseModule (emsModSummary ems)