Make 'count-deps' a ghc/util standalone program

- Move 'count-deps' into 'ghc/utils' so that it can be called standalone.
- Move 'testsuite/tests/parser/should_run/' tests 'CountParserDeps' and
'CountAstDeps' to 'testsuite/tests/count-deps' and reimplement in terms
of calling the utility
- Document how to use 'count-deps' in 'ghc/utils/count-deps/README'

9 files changed, 29 insertions, 112 deletions

diff --git a/testsuite/mk/boilerplate.mk b/testsuite/mk/boilerplate.mk
index a2fb56d1ba..942e6e32c2 100644
--- a/testsuite/mk/boilerplate.mk
+++ b/testsuite/mk/boilerplate.mk
@@ -227,6 +227,10 @@ ifeq "$(CHECK_EXACT)" ""
 CHECK_EXACT := $(abspath $(TOP)/../inplace/bin/check-exact)
 endif
 
+ifeq "$(COUNT_DEPS)" ""
+COUNT_DEPS := $(abspath $(TOP)/../inplace/bin/count-deps)
+endif
+
 # -----------------------------------------------------------------------------
 # configuration of TEST_HC
 
@@ -296,4 +300,3 @@ FREEBSD = YES
 else
 FREEBSD = NO
 endif
-
diff --git a/testsuite/tests/parser/should_run/CountAstDeps.stdout b/testsuite/tests/count-deps/CountDepsAst.stdout
index 4b33ad2982..4b33ad2982 100644
--- a/testsuite/tests/parser/should_run/CountAstDeps.stdout
+++ b/testsuite/tests/count-deps/CountDepsAst.stdout
diff --git a/testsuite/tests/parser/should_run/CountParserDeps.stdout b/testsuite/tests/count-deps/CountDepsParser.stdout
index 16dbb8e185..16dbb8e185 100644
--- a/testsuite/tests/parser/should_run/CountParserDeps.stdout
+++ b/testsuite/tests/count-deps/CountDepsParser.stdout
diff --git a/testsuite/tests/count-deps/Makefile b/testsuite/tests/count-deps/Makefile
new file mode 100644
index 0000000000..41911c47df
--- /dev/null
+++ b/testsuite/tests/count-deps/Makefile
@@ -0,0 +1,23 @@
+TOP=../..
+include $(TOP)/mk/boilerplate.mk
+include $(TOP)/mk/test.mk
+
+LIBDIR := "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`"
+
+# Calculate the number of module dependencies of 'Parser.' If that
+# number exceeds a threshold, that indicates that the dependencies
+# have significantly gone up via the commit under test (and the test
+# is deemed to fail). In that case, this most likely means a cycle
+# has arisen that pulls in modules for Core generation. The
+# motivation for not allowing that to happen is so that the
+# 'ghc-lib-parser' package subset of the GHC API can continue to be
+# provided with as small a number of modules as possible for when the
+# need exists to produce ASTs and nothing more.
+
+.PHONY: count-deps-parser
+count-deps-parser:
+	$(COUNT_DEPS) $(LIBDIR) "GHC.Parser"
+
+.PHONY: count-deps-ast
+count-deps-ast:
+	$(COUNT_DEPS) $(LIBDIR) "Language.Haskell.Syntax"
diff --git a/testsuite/tests/count-deps/all.T b/testsuite/tests/count-deps/all.T
new file mode 100644
index 0000000000..6b8abd9c95
--- /dev/null
+++ b/testsuite/tests/count-deps/all.T
@@ -0,0 +1,2 @@
+test('CountDepsAst', [], makefile_test, ['count-deps-ast'])
+test('CountDepsParser', [], makefile_test, ['count-deps-parser'])
diff --git a/testsuite/tests/parser/should_run/CountAstDeps.hs b/testsuite/tests/parser/should_run/CountAstDeps.hs
deleted file mode 100644
index ba7f0c50f9..0000000000
--- a/testsuite/tests/parser/should_run/CountAstDeps.hs
+++ /dev/null
@@ -1,16 +0,0 @@
-module Main(main) where
-
--- Calculate the number of module dependencies of 'Parser.' If that
--- number exceeds a threshold, that indicates that the dependencies
--- have significantly gone up via the commit under test (and the test
--- is deemed to fail). In that case, this most likely means a cycle
--- has arisen that pulls in modules for Core generation. The
--- motivation for not allowing that to happen is so that the
--- 'ghc-lib-parser' package subset of the GHC API can continue to be
--- provided with as small a number of modules as possible for when the
--- need exists to produce ASTs and nothing more.
-
-import CountDeps
-
-main :: IO ()
-main = printDeps "Language.Haskell.Syntax"
diff --git a/testsuite/tests/parser/should_run/CountDeps.hs b/testsuite/tests/parser/should_run/CountDeps.hs
deleted file mode 100644
index fab36de4a8..0000000000
--- a/testsuite/tests/parser/should_run/CountDeps.hs
+++ /dev/null
@@ -1,71 +0,0 @@
-module CountDeps (printDeps) where
-
-import GHC.Driver.Env
-import GHC.Unit.Module
-import GHC.Driver.Session
-import GHC.Driver.Main
-import GHC
-import GHC.Utils.Misc
-import Data.Maybe
-import Control.Monad
-import Control.Monad.IO.Class
-import System.Environment
-import System.Exit
-import GHC.Unit.Module.Deps
-import Data.Map.Strict qualified as Map
-
-dotSpec :: String -> Map.Map String [String] -> String
-dotSpec name g =
- "digraph \"" ++ name ++ "\" {\n" ++
-    Map.foldlWithKey' f "" g ++ "}\n"
-  where
-    f acc k ns = acc ++ concat ["  " ++ show k ++ " -> " ++ show n ++ ";\n" | n <- ns]
-
-printDeps :: String -> IO ()
-printDeps modName = do
-  [libdir] <- getArgs
-  modGraph <-
-    Map.map (map moduleNameString) .
-      Map.mapKeys moduleNameString <$> calcDeps modName libdir
-  let modules = Map.keys modGraph
-      num = length modules
-  putStrLn $ "Found " ++ show num ++ " " ++ modName ++ " module dependencies"
-  forM_ modules putStrLn
-  -- Uncomment the next line to print a dependency graph in dot
-  -- format:
-  -- putStr $ dotSpec modName modGraph
-  -- Then,
-  -- * Copy the digraph output to a file ('deps.dot' say)
-  -- * To render it, use a command along the lines of
-  --   'tred deps.dot > deps-tred.dot && dot -Tpdf -o deps.pdf deps-tred.dot'
-
-calcDeps :: String -> FilePath -> IO (Map.Map ModuleName [ModuleName])
-calcDeps modName libdir =
-  defaultErrorHandler defaultFatalMessager defaultFlushOut $ do
-    runGhc (Just libdir) $ do
-        df <- getSessionDynFlags
-        logger <- getLogger
-        (df, _, _) <- parseDynamicFlags logger df [noLoc "-package=ghc"]
-        setSessionDynFlags df
-        env <- getSession
-        loop env Map.empty [mkModuleName modName]
-  where
-    -- Source imports are only guaranteed to show up in the 'mi_deps'
-    -- of modules that import them directly and don’t propagate
-    -- transitively so we loop.
-    loop :: HscEnv -> Map.Map ModuleName [ModuleName] -> [ModuleName] -> Ghc (Map.Map ModuleName [ModuleName])
-    loop env modules (m : ms) =
-      if m `Map.member` modules
-        then loop env modules ms
-        else do
-          mi <- liftIO $ hscGetModuleInterface env (mkModule m)
-          let deps = modDeps mi
-          modules <- return $ Map.insert m [] modules
-          loop env (Map.insert m deps modules) $ ms ++ filter (not . (`Map.member` modules)) deps
-    loop _ modules [] = return modules
-
-    mkModule :: ModuleName -> Module
-    mkModule = Module (stringToUnit "ghc")
-
-    modDeps :: ModIface -> [ModuleName]
-    modDeps mi = map gwib_mod $ dep_direct_mods (mi_deps mi)
diff --git a/testsuite/tests/parser/should_run/CountParserDeps.hs b/testsuite/tests/parser/should_run/CountParserDeps.hs
deleted file mode 100644
index f1dacb1d62..0000000000
--- a/testsuite/tests/parser/should_run/CountParserDeps.hs
+++ /dev/null
@@ -1,16 +0,0 @@
-module Main(main) where
-
--- Calculate the number of module dependencies of 'Parser.' If that
--- number exceeds a threshold, that indicates that the dependencies
--- have significantly gone up via the commit under test (and the test
--- is deemed to fail). In that case, this most likely means a cycle
--- has arisen that pulls in modules for Core generation. The
--- motivation for not allowing that to happen is so that the
--- 'ghc-lib-parser' package subset of the GHC API can continue to be
--- provided with as small a number of modules as possible for when the
--- need exists to produce ASTs and nothing more.
-
-import CountDeps
-
-main :: IO ()
-main = printDeps "GHC.Parser"
diff --git a/testsuite/tests/parser/should_run/all.T b/testsuite/tests/parser/should_run/all.T
index 5c2112057e..92c6d0fcb3 100644
--- a/testsuite/tests/parser/should_run/all.T
+++ b/testsuite/tests/parser/should_run/all.T
@@ -14,14 +14,6 @@ test('NegativeZero', normal, compile_and_run, [''])
 test('HexFloatLiterals', normal, compile_and_run, [''])
 test('NumericUnderscores0', normal, compile_and_run, [''])
 test('NumericUnderscores1', normal, compile_and_run, [''])
-test('CountAstDeps',
-     [ extra_files(['CountDeps.hs']), only_ways(['normal']), extra_run_opts('"' + config.libdir + '"') ],
-     compile_and_run,
-     ['-package ghc'])
-test('CountParserDeps',
-     [ extra_files(['CountDeps.hs']), only_ways(['normal']), extra_run_opts('"' + config.libdir + '"') ],
-     compile_and_run,
-     ['-package ghc'])
 test('LexNegLit', normal, compile_and_run, [''])
 test('RecordDotSyntax1', normal, compile_and_run, [''])
 test('RecordDotSyntax2', normal, compile_and_run, [''])