Move linters into the tree

This MR moves the GHC linters into the tree, so that they can be run directly using Hadrian.

* Query all files tracked by Git instead of using changed files, so that we can run the exact same linting step locally and in a merge request.
* Only check that the changelogs don't contain TBA when RELEASE=YES.
* Add hadrian/lint script, which runs all the linting steps.
* Ensure the hlint job exits with a failure if hlint is not installed (otherwise we were ignoring the failure). Given that hlint doesn't seem to be available in CI at the moment, I've temporarily allowed failure in the hlint job.
* Run all linting tests in CI using hadrian.

42 files changed, 1166 insertions, 163 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0a2d34db8d..c6d95612a5 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -157,7 +157,7 @@ not-interruptible:
   stage: not-interruptible
   script: "true"
   interruptible: false
-  image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
+  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:$DOCKER_REV"
   tags:
     - lint
   rules:
@@ -175,39 +175,24 @@ not-interruptible:
 
 ghc-linters:
   stage: tool-lint
-  image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
-  extends: .lint
-  script:
-    - git fetch "$CI_MERGE_REQUEST_PROJECT_URL" $CI_MERGE_REQUEST_TARGET_BRANCH_NAME
-    - base="$(git merge-base FETCH_HEAD $CI_COMMIT_SHA)"
-    - "echo Linting changes between $base..$CI_COMMIT_SHA"
-    #    - validate-commit-msg .git $(git rev-list $base..$CI_COMMIT_SHA)
-    - validate-whitespace .git $(git rev-list $base..$CI_COMMIT_SHA)
-    - .gitlab/linters/check-makefiles.py commits $base $CI_COMMIT_SHA
-    - .gitlab/linters/check-cpp.py commits $base $CI_COMMIT_SHA
-    - .gitlab/linters/check-version-number.sh
-    - python3 testsuite/tests/linters/checkUniques/check-uniques.py .
-  dependencies: []
-  rules:
-    - if: $CI_MERGE_REQUEST_ID
-    - *drafts-can-fail-lint
-
-lint-notes:
-  image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
+  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:$DOCKER_REV"
   extends: .lint-params
   variables:
     BUILD_FLAVOUR: default
   script:
     - .gitlab/ci.sh configure
-    - .gitlab/ci.sh run_hadrian test --only="notes"
+    - .gitlab/ci.sh run_hadrian test --test-root-dirs="testsuite/tests/linters"
   dependencies: []
+  rules:
+    - if: $CI_MERGE_REQUEST_ID
+    - *drafts-can-fail-lint
 
 # Run mypy Python typechecker on linter scripts.
 lint-linters:
   image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
   extends: .lint
   script:
-    - mypy .gitlab/linters/*.py
+    - mypy testsuite/tests/linters/regex-linters/*.py
   dependencies: []
 
 # Check that .T files all parse by listing broken tests.
@@ -230,14 +215,18 @@ typecheck-testsuite:
 # accommodate, e.g., haddock changes not yet upstream) but not on `master` or
 # Marge jobs.
 .lint-submods:
-  image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
-  extends: .lint
+  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:$DOCKER_REV"
+  extends: .lint-params
+  variables:
+    BUILD_FLAVOUR: default
   script:
+    - .gitlab/ci.sh configure
+    - .gitlab/ci.sh run_hadrian stage1:exe:lint-submodule-refs
     - git fetch "$CI_MERGE_REQUEST_PROJECT_URL" $CI_MERGE_REQUEST_TARGET_BRANCH_NAME
     - base="$(git merge-base FETCH_HEAD $CI_COMMIT_SHA)"
     - "echo Linting submodule changes between $base..$CI_COMMIT_SHA"
     - git submodule foreach git remote update
-    - submodchecker . $(git rev-list $base..$CI_COMMIT_SHA)
+    - _build/stage0/bin/lint-submodule-refs . $(git rev-list $base..$CI_COMMIT_SHA)
   dependencies: []
 
 lint-submods:
@@ -251,34 +240,55 @@ lint-submods:
 
 lint-submods-branch:
   extends: .lint-submods
+  variables:
+    BUILD_FLAVOUR: default
   script:
+    - .gitlab/ci.sh configure
+    - .gitlab/ci.sh run_hadrian stage1:exe:lint-submodule-refs
     - "echo Linting submodule changes between $CI_COMMIT_BEFORE_SHA..$CI_COMMIT_SHA"
     - git submodule foreach git remote update
-    - submodchecker . $(git rev-list $CI_COMMIT_BEFORE_SHA..$CI_COMMIT_SHA)
+    - _build/stage0/bin/lint-submodule-refs . $(git rev-list $CI_COMMIT_BEFORE_SHA..$CI_COMMIT_SHA)
   rules:
     - if: '$CI_COMMIT_BRANCH == "master"'
     - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/'
     - *drafts-can-fail-lint
 
-.lint-changelogs:
-  image: "registry.gitlab.haskell.org/ghc/ci-images/linters:$DOCKER_REV"
+############################################################
+# GHC source code linting
+############################################################
+
+.lint-params:
+  needs: []
+  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:$DOCKER_REV"
   extends: .lint
-  dependencies: []
-  script:
-    - bash .gitlab/linters/check-changelogs.sh
+  before_script:
+    - export PATH="/opt/toolchain/bin:$PATH"
+    # workaround for docker permissions
+    - sudo chown ghc:ghc -R .
+    - git submodule sync --recursive
+    - git submodule update --init --recursive
+    - git checkout .gitmodules
+    - .gitlab/ci.sh setup
+  after_script:
+    - .gitlab/ci.sh save_cache
+    - cat ci-timings
+  variables:
+    GHC_FLAGS: -Werror
+  cache:
+    key: lint-$CACHE_REV
+    paths:
+      - cabal-cache
 
-lint-changelogs:
-  extends: .lint-changelogs
-  # Allow failure since this isn't a final release.
+hlint-ghc-and-base:
+  extends: .lint-params
+  variables:
+    BUILD_FLAVOUR: default
+  script:
+    - .gitlab/ci.sh setup
+    - .gitlab/ci.sh configure
+    - .gitlab/ci.sh run_hadrian lint:base
+    - .gitlab/ci.sh run_hadrian lint:compiler
   allow_failure: true
-  rules:
-    - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/'
-
-lint-release-changelogs:
-  extends: .lint-changelogs
-  rules:
-    - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/'
-    - *drafts-can-fail-lint
 
 ############################################################
 # Validation via Pipelines (hadrian)
@@ -410,42 +420,6 @@ hadrian-ghc-in-ghci:
       - cabal-cache
 
 ############################################################
-# GHC source code linting
-############################################################
-
-.lint-params:
-  needs: []
-  image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-deb10:$DOCKER_REV"
-  extends: .lint
-  before_script:
-    - export PATH="/opt/toolchain/bin:$PATH"
-    # workaround for docker permissions
-    - sudo chown ghc:ghc -R .
-    - git submodule sync --recursive
-    - git submodule update --init --recursive
-    - git checkout .gitmodules
-    - .gitlab/ci.sh setup
-  after_script:
-    - .gitlab/ci.sh save_cache
-    - cat ci-timings
-  variables:
-    GHC_FLAGS: -Werror
-  cache:
-    key: lint-$CACHE_REV
-    paths:
-      - cabal-cache
-
-lint-libs:
-  extends: .lint-params
-  variables:
-    BUILD_FLAVOUR: default
-  script:
-    - .gitlab/ci.sh setup
-    - .gitlab/ci.sh configure
-    - .gitlab/ci.sh run_hadrian lint:base
-    - .gitlab/ci.sh run_hadrian lint:compiler
-
-############################################################
 # Validation via Pipelines (make)
 ############################################################
 
diff --git a/.gitlab/linters/check-changelogs.sh b/.gitlab/linters/check-changelogs.sh
deleted file mode 100755
index 56ac187a90..0000000000
--- a/.gitlab/linters/check-changelogs.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-
-COLOR_RED="\e[31m"
-COLOR_GREEN="\e[32m"
-COLOR_NONE="\e[0m"
-
-grep TBA libraries/*/changelog.md && (
-    echo -e "${COLOR_RED}Error: Found \"TBA\"s in changelogs.${COLOR_NONE}"
-    exit 1
-) || (
-    echo -e "${COLOR_GREEN}changelogs look okay.${COLOR_NONE}"
-    exit 0
-)
-
diff --git a/cabal.project-reinstall b/cabal.project-reinstall
index e026e70a5d..aa6fc0c47e 100644
--- a/cabal.project-reinstall
+++ b/cabal.project-reinstall
@@ -46,6 +46,7 @@ packages: ./compiler
           ./utils/runghc
           ./utils/unlit
           ./utils/iserv
+          ./linters/**/*.cabal
 
 constraints: ghc +internal-interpreter +dynamic-system-linke +terminfo,
              ghc-bin +internal-interpreter +threaded,
diff --git a/ghc.mk b/ghc.mk
index 683a04d571..68496cd83a 100644
--- a/ghc.mk
+++ b/ghc.mk
@@ -546,13 +546,15 @@ utils/ghc-pkg/dist-install/package-data.mk: $(fixed_pkg_prev)
 utils/hsc2hs/dist-install/package-data.mk: $(fixed_pkg_prev)
 utils/compare_sizes/dist-install/package-data.mk: $(fixed_pkg_prev)
 utils/runghc/dist-install/package-data.mk: $(fixed_pkg_prev)
-utils/notes-util/dist-install/package-data.mk: $(fixed_pkg_prev)
 utils/iserv/stage2/package-data.mk: $(fixed_pkg_prev)
 utils/iserv/stage2_p/package-data.mk: $(fixed_pkg_prev)
 utils/iserv/stage2_dyn/package-data.mk: $(fixed_pkg_prev)
 ifeq "$(Windows_Host)" "YES"
 utils/gen-dll/dist-install/package-data.mk: $(fixed_pkg_prev)
 endif
+linters/linters-common/dist-install/package-data.mk: $(fixed_pkg_prev)
+linters/lint-notes/dist-install/package-data.mk: $(fixed_pkg_prev) linters/linters-common/dist-install/package-data.mk
+linters/lint-whitespace/dist-install/package-data.mk: $(fixed_pkg_prev) linters/linters-common/dist-install/package-data.mk
 
 # the GHC package doesn't live in libraries/, so we add its dependency manually:
 compiler/stage2/package-data.mk: $(fixed_pkg_prev)
@@ -669,7 +671,6 @@ BUILD_DIRS += utils/hsc2hs
 BUILD_DIRS += utils/ghc-pkg
 BUILD_DIRS += utils/testremove
 BUILD_DIRS += utils/check-ppr
-BUILD_DIRS += utils/notes-util
 BUILD_DIRS += utils/check-exact
 BUILD_DIRS += utils/count-deps
 BUILD_DIRS += utils/ghc-cabal
@@ -679,6 +680,9 @@ BUILD_DIRS += ghc
 BUILD_DIRS += docs/users_guide
 BUILD_DIRS += utils/compare_sizes
 BUILD_DIRS += utils/iserv
+BUILD_DIRS += linters/linters-common
+BUILD_DIRS += linters/lint-notes
+BUILD_DIRS += linters/lint-whitespace
 
 # ----------------------------------------------
 # Actually include the sub-ghc.mk's
@@ -1092,7 +1096,7 @@ BIN_DIST_MK = $(BIN_DIST_PREP_DIR)/bindist.mk
 unix-binary-dist-prep: $(includes_dist-install_H_FILES_GENERATED)
 	$(call removeTrees,bindistprep/)
 	"$(MKDIRHIER)" $(BIN_DIST_PREP_DIR)
-	set -e; for i in packages LICENSE compiler ghc rts libraries utils docs libffi includes driver mk rules Makefile m4 aclocal.m4 config.sub config.guess install-sh llvm-targets llvm-passes ghc.mk inplace distrib/configure.ac distrib/README distrib/INSTALL; do ln -s ../../$$i $(BIN_DIST_PREP_DIR)/; done
+	set -e; for i in packages LICENSE compiler ghc rts libraries linters utils docs libffi includes driver mk rules Makefile m4 aclocal.m4 config.sub config.guess install-sh llvm-targets llvm-passes ghc.mk inplace distrib/configure.ac distrib/README distrib/INSTALL; do ln -s ../../$$i $(BIN_DIST_PREP_DIR)/; done
 	echo "HADDOCK_DOCS       = $(HADDOCK_DOCS)"       >> $(BIN_DIST_MK)
 	echo "BUILD_SPHINX_HTML  = $(BUILD_SPHINX_HTML)"  >> $(BIN_DIST_MK)
 	echo "BUILD_SPHINX_PDF   = $(BUILD_SPHINX_PDF)"   >> $(BIN_DIST_MK)
diff --git a/hadrian/lint b/hadrian/lint
new file mode 100644
index 0000000000..8c43c89bd1
--- /dev/null
+++ b/hadrian/lint
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+"hadrian/build" "$@" test --test-root-dirs="testsuite/tests/linters"
+  # hlint targets disabled as they do not currently run on CI.
+  # lint:compiler lint:base
diff --git a/hadrian/src/Packages.hs b/hadrian/src/Packages.hs
index a44e3cd95e..9ca18f14c3 100644
--- a/hadrian/src/Packages.hs
+++ b/hadrian/src/Packages.hs
@@ -9,7 +9,9 @@ module Packages (
     hsc2hs, hp2ps, hpc, hpcBin, integerGmp, integerSimple, iserv, iservProxy,
     libffi, libiserv, mtl, parsec, pretty, primitive, process, remoteIserv, rts,
     runGhc, stm, templateHaskell, terminfo, text, time, timeout, touchy,
-    transformers, unlit, unix, win32, xhtml, noteLinter, ghcPackages, isGhcPackage,
+    transformers, unlit, unix, win32, xhtml,
+    lintersCommon, lintNotes, lintCommitMsg, lintSubmoduleRefs, lintWhitespace,
+    ghcPackages, isGhcPackage,
 
     -- * Package information
     programName, nonHsMainPackage, autogenPath, programPath, timeoutPath,
@@ -39,13 +41,25 @@ ghcPackages =
     , hp2ps, hpc, hpcBin, integerGmp, integerSimple, iserv, libffi, libiserv, mtl
     , parsec, pretty, process, rts, runGhc, stm, templateHaskell
     , terminfo, text, time, touchy, transformers, unlit, unix, win32, xhtml
-    , timeout, noteLinter ]
+    , timeout
+    , lintersCommon
+    , lintNotes, lintCommitMsg, lintSubmoduleRefs, lintWhitespace ]
 
 -- TODO: Optimise by switching to sets of packages.
 isGhcPackage :: Package -> Bool
 isGhcPackage = (`elem` ghcPackages)
 
 -- | Package definitions, see 'Package'.
+array, base, binary, bytestring, cabalSyntax, cabal, checkPpr, checkExact, countDeps,
+  compareSizes, compiler, containers, deepseq, deriveConstants, directory,
+  exceptions, filepath, genapply, genprimopcode, ghc, ghcBignum, ghcBoot, ghcBootTh,
+  ghcCompact, ghcHeap, ghci, ghciWrapper, ghcPkg, ghcPrim, haddock, haskeline, hsc2hs,
+  hp2ps, hpc, hpcBin, integerGmp, integerSimple, iserv, iservProxy, remoteIserv, libffi, libiserv, mtl,
+  parsec, pretty, primitive, process, rts, runGhc, stm, templateHaskell,
+  terminfo, text, time, touchy, transformers, unlit, unix, win32, xhtml,
+  timeout,
+  lintersCommon, lintNotes, lintCommitMsg, lintSubmoduleRefs, lintWhitespace
+    :: Package
 array               = lib  "array"
 base                = lib  "base"
 binary              = lib  "binary"
@@ -108,7 +122,12 @@ unlit               = util "unlit"
 unix                = lib  "unix"
 win32               = lib  "Win32"
 xhtml               = lib  "xhtml"
-noteLinter          = prg  "notes-util"      `setPath` "utils/notes-util"
+
+lintersCommon       = lib     "linters-common"      `setPath` "linters/linters-common"
+lintNotes           = linter  "lint-notes"
+lintCommitMsg       = linter  "lint-commit-msg"
+lintSubmoduleRefs   = linter  "lint-submodule-refs"
+lintWhitespace      = linter  "lint-whitespace"
 
 -- | Construct a library package, e.g. @array@.
 lib :: PackageName -> Package
@@ -126,6 +145,10 @@ prg name = program name name
 util :: PackageName -> Package
 util name = program name ("utils" -/- name)
 
+-- | Construct a linter executable program (lives in the \"linters\" subdirectory).
+linter :: PackageName -> Package
+linter name = program name ("linters" -/- name)
+
 -- | Amend a package path if it doesn't conform to a typical pattern.
 setPath :: Package -> FilePath -> Package
 setPath pkg path = pkg { pkgPath = path }
diff --git a/hadrian/src/Rules/Docspec.hs b/hadrian/src/Rules/Docspec.hs
index 69b49a1cc5..30f6a039eb 100644
--- a/hadrian/src/Rules/Docspec.hs
+++ b/hadrian/src/Rules/Docspec.hs
@@ -8,6 +8,7 @@ import Base
 import Context.Path
 import Settings.Builders.Common
 import qualified Packages as P
+import System.Exit (exitFailure)
 
 docspecRules :: Rules ()
 docspecRules = do
@@ -21,8 +22,9 @@ docspec lintAction = do
     putBuild "| Running cabal-docspec…"
     lintAction
     putSuccess "| Done."
-  else
+  else do
     putFailure "| Please make sure you have the `cabal-docspec` executable in your $PATH"
+    liftIO exitFailure
 
 base :: Action ()
 base = do
diff --git a/hadrian/src/Rules/Lint.hs b/hadrian/src/Rules/Lint.hs
index bb7df1687a..58f9715f21 100644
--- a/hadrian/src/Rules/Lint.hs
+++ b/hadrian/src/Rules/Lint.hs
@@ -5,6 +5,7 @@ module Rules.Lint
 import Base
 import Settings.Builders.Common
 import System.Directory (findExecutable)
+import System.Exit (exitFailure)
 
 lintRules :: Rules ()
 lintRules = do
@@ -19,8 +20,9 @@ lint lintAction = do
     putBuild "| Running the linter…"
     lintAction
     putSuccess "| Done."
-  else
+  else do
     putFailure "| Please make sure you have the `hlint` executable in your $PATH"
+    liftIO exitFailure
 
 runHLint :: [FilePath] -- ^ include directories
          -> [String]   -- ^ CPP defines
diff --git a/hadrian/src/Rules/Test.hs b/hadrian/src/Rules/Test.hs
index fe0aba04cc..4b0ba4a913 100644
--- a/hadrian/src/Rules/Test.hs
+++ b/hadrian/src/Rules/Test.hs
@@ -44,17 +44,24 @@ countDepsExtra :: Maybe String
 countDepsExtra = Just "-iutils/count-deps"
 
 noteLinterProgPath, noteLinterSourcePath :: FilePath
-noteLinterProgPath = "test/bin/notes-util" <.> exe
-noteLinterSourcePath = "utils/notes-util/Main.hs"
+noteLinterProgPath = "test/bin/lint-notes" <.> exe
+noteLinterSourcePath = "linters/lint-notes/Main.hs"
 noteLinterExtra :: Maybe String
-noteLinterExtra = Just "-iutils/notes-util"
+noteLinterExtra = Just "-ilinters/lint-notes"
+
+whitespaceLinterProgPath, whitespaceLinterSourcePath :: FilePath
+whitespaceLinterProgPath = "test/bin/lint-whitespace" <.> exe
+whitespaceLinterSourcePath = "linters/lint-whitespace/Main.hs"
+whitespaceLinterExtra :: Maybe String
+whitespaceLinterExtra = Just "-ilinters/lint-whitespace"
 
 checkPrograms :: [(String,FilePath, FilePath, Maybe String, Package, Stage -> Stage)]
 checkPrograms =
     [ ("test:check-ppr",checkPprProgPath, checkPprSourcePath, checkPprExtra, checkPpr, id)
     , ("test:check-exact",checkExactProgPath, checkExactSourcePath, checkExactExtra, checkExact, id)
     , ("test:count-deps",countDepsProgPath, countDepsSourcePath, countDepsExtra, countDeps, id)
-    , ("lint:notes-util", noteLinterProgPath, noteLinterSourcePath, noteLinterExtra, noteLinter, const Stage0)
+    , ("lint:notes", noteLinterProgPath, noteLinterSourcePath, noteLinterExtra, lintNotes, const Stage0)
+    , ("lint:whitespace", whitespaceLinterProgPath, whitespaceLinterSourcePath, whitespaceLinterExtra, lintWhitespace, const Stage0)
     ]
 
 inTreeOutTree :: (Stage -> Action b) -> Action b -> Action b
@@ -213,7 +220,8 @@ testRules = do
             setEnv "CHECK_PPR" (top -/- root -/- checkPprProgPath)
             setEnv "CHECK_EXACT" (top -/- root -/- checkExactProgPath)
             setEnv "COUNT_DEPS" (top -/- root -/- countDepsProgPath)
-            setEnv "NOTES_UTIL" (top -/- root -/- noteLinterProgPath)
+            setEnv "LINT_NOTES" (top -/- root -/- noteLinterProgPath)
+            setEnv "LINT_WHITESPACE" (top -/- root -/- whitespaceLinterProgPath)
 
             -- This lets us bypass the need to generate a config
             -- through Make, which happens in testsuite/mk/boilerplate.mk
diff --git a/hadrian/src/Settings/Default.hs b/hadrian/src/Settings/Default.hs
index 8c490347b9..21ab008cb7 100644
--- a/hadrian/src/Settings/Default.hs
+++ b/hadrian/src/Settings/Default.hs
@@ -87,7 +87,11 @@ stage0Packages = do
              , text
              , transformers
              , unlit
-             , noteLinter
+             , lintersCommon
+             , lintNotes
+             , lintCommitMsg
+             , lintSubmoduleRefs
+             , lintWhitespace
              ]
           ++ [ terminfo | not windowsHost, not cross ]
           ++ [ timeout  | windowsHost                ]
diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md
index 44ac94c32b..a905e2d2f3 100644
--- a/libraries/base/changelog.md
+++ b/libraries/base/changelog.md
@@ -111,7 +111,7 @@
 
     - `oneBits :: FiniteBits a => a`, `oneBits = complement zeroBits`.
 
-## 4.15.0.0 *TBA*
+## 4.15.0.0 *Feb 2021*
 
   * `openFile` now calls the `open` system call with an `interruptible` FFI
     call, ensuring that the call can be interrupted with `SIGINT` on POSIX
diff --git a/linters/lint-commit-msg/Main.hs b/linters/lint-commit-msg/Main.hs
new file mode 100644
index 0000000000..cf12b19ba5
--- /dev/null
+++ b/linters/lint-commit-msg/Main.hs
@@ -0,0 +1,160 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiWayIf #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+{-# OPTIONS_GHC -Wno-missing-local-signatures #-}
+
+module Main where
+
+-- base
+import           Control.Monad
+  ( forM, forM_, unless, when )
+import           Data.Maybe
+  ( isJust )
+import           System.Environment
+  ( getArgs )
+import           System.Exit
+  ( ExitCode(..), exitWith )
+
+-- mtl
+import           Control.Monad.Writer
+  ( liftIO, execWriter, tell )
+
+-- text
+import           Data.Text
+  ( Text )
+import qualified Data.Text    as T
+import qualified Data.Text.IO as T
+  ( putStrLn )
+
+-- linters-common
+import           Linters.Common
+  ( LintMsg(..), LintLvl(..)
+  , gitCatCommit, gitNormCid, tshow
+  )
+
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = do
+    dir:refs <- getArgs >>= \case
+        [] -> fail "usage: lint-commit-msg <git-repo> [<commit-id>+]"
+        x  -> return x
+
+    stats <- forM (map T.pack refs) $ \ref -> do
+        cid <- gitNormCid dir ref
+        (_, msg) <- gitCatCommit dir cid
+
+        let cmsgs = lintMsg msg
+
+        liftIO $ do
+            -- putStrLn (T.unpack cid)
+            -- forM_ (zip [1::Int ..] (T.lines msg)) $ \(lno,l) -> do
+            --     putStrLn (show lno <> "\t" <> show l)
+            -- putStrLn "--"
+
+            let status = maximum (Nothing : [ Just lvl | LintMsg lvl _ _ _ <- cmsgs ])
+                ok     = status < Just LintLvlErr
+
+            unless (null cmsgs) $ do
+                putStrLn "====================================================================================="
+                putStrLn ("commit " <> T.unpack cid <> " has linter issues:")
+                putStrLn ""
+                forM_ cmsgs $ \(LintMsg lvl lno l m) -> do
+                    let lvls = case lvl of
+                            LintLvlErr  -> "*ERROR*"
+                            LintLvlWarn -> "Warning"
+                    putStrLn (" " <> lvls <> " on line " <> show lno <> ": " <> T.unpack m)
+                    putStrLn (" > " <> show l)
+                    putStrLn ""
+                    return ()
+
+            unless ok $
+                putStrLn ("Validation FAILED for " <> T.unpack cid)
+
+            return status
+
+    unless (null $ filter isJust stats) $
+        T.putStrLn "====================================================================================="
+
+    let stats1 = maximum (Nothing : stats)
+
+    unless (stats1 == Nothing) $ do
+        T.putStrLn "There were commit message linter issues! For more information see"
+        T.putStrLn " http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html"
+        T.putStrLn ""
+
+    unless (stats1 < Just LintLvlErr) $ do
+        T.putStrLn "Validation FAILED because at least one commit had linter errors!"
+        exitWith (ExitFailure 1)
+
+    T.putStrLn "Commit message validation passed!"
+
+-- | Commit message linter
+lintMsg :: Text -> [LintMsg]
+lintMsg msg0 = execWriter $ do
+    -- subject-line validations
+    if | T.null (T.strip subj) -> errSubj "empty subject line"
+       | otherwise -> do
+           when (T.stripStart subj /= subj) $
+               errSubj "subject line with leading whitespace"
+
+           when (T.stripEnd subj /= subj) $
+               warnSubj "subject line with trailing whitespace"
+
+           when (T.any (== '\t') subj) $
+               errSubj "subject line contains TAB"
+
+           if | slen > 80 -> errSubj  ("subject line longer than 80 characters (was " <> tshow slen <> " characters)"
+                                       <> " -- , ideally subject line is at most 50 characters long")
+              | slen > 50 -> warnSubj ("subject line longer than 50 characters (was " <> tshow slen <> " characters)")
+              | slen < 8  -> errSubj  ("subject line shorter than 8 characters (was " <> tshow slen <> " characters)")
+              | otherwise -> return ()
+
+    -- 2nd-line & body validations
+    case lns of
+        []  -> return () -- empty commit msg -- will have caused already an LintLvlErr
+        [_] -> return () -- single-line commit msg
+        (_:line2:body) -> do
+            -- 2nd line validations
+            if | not (T.null line2)
+                   -> tell [LintMsg LintLvlErr  2 line2 "2nd line must be empty"]
+               | null body
+                   -> tell [LintMsg LintLvlWarn 2 line2 "2nd line exists, but no commit msg body found"]
+               | otherwise -> return ()
+
+            -- body validations
+            forM_ (zip [3..] body) $ \(lineno,l) -> do
+                let llen = T.length l
+                    warnBody m = tell [LintMsg LintLvlWarn lineno l m]
+                    errBody  m = tell [LintMsg LintLvlErr  lineno l m]
+
+                when (T.stripEnd l /= l) $ warnBody "trailing whitespace"
+
+                when (T.any (== '\t') l) $ warnBody "contains TAB character"
+
+                when (T.isPrefixOf "Summary:" l) $
+                    warnBody "redundant Phabricator 'Summary:' tag detected -- please trim your commit message"
+
+                when (T.isPrefixOf "Summary: Signed-off-by:" l) $
+                    errBody "'Signed-Off-by:'-marker not starting on first column"
+
+                if | llen > 100 -> errBody  ("body line longer than 100 characters (was "
+                                             <> tshow llen <> " characters) -- "
+                                             <> "ideally body lines are at most 72 characters long")
+                   | llen > 72  -> warnBody ("body line longer than 72 characters (was "
+                                             <> tshow llen <> " characters)")
+                   | otherwise  -> return ()
+
+    return ()
+  where
+    warnSubj m = tell [LintMsg LintLvlWarn 1 subj m]
+    errSubj  m = tell [LintMsg LintLvlErr  1 subj m]
+
+    lns = T.lines msg0
+
+    subj | (l0:_) <- lns = l0
+         | otherwise     = ""
+
+    slen = T.length subj
diff --git a/linters/lint-commit-msg/cabal.project b/linters/lint-commit-msg/cabal.project
new file mode 100644
index 0000000000..444b636706
--- /dev/null
+++ b/linters/lint-commit-msg/cabal.project
@@ -0,0 +1,2 @@
+packages: .,
+          ../linters-common
diff --git a/linters/lint-commit-msg/lint-commit-msg.cabal b/linters/lint-commit-msg/lint-commit-msg.cabal
new file mode 100644
index 0000000000..8020a925a4
--- /dev/null
+++ b/linters/lint-commit-msg/lint-commit-msg.cabal
@@ -0,0 +1,29 @@
+cabal-version:       3.0
+name:                lint-commit-msg
+version:             0.1.0.0
+synopsis:            Lint a commit message
+license:             GPL-3.0-only
+author:              The GHC team
+build-type:          Simple
+
+executable lint-commit-msg
+  ghc-options:
+    -Wall
+
+  default-language:
+    Haskell2010
+
+  hs-source-dirs:
+    .
+
+  main-is:
+    Main.hs
+
+  build-depends:
+    linters-common,
+    mtl
+      >=2.1 && <2.3,
+    base
+       >= 4.14 && < 5,
+    text
+       >= 1.2  && < 2.1
diff --git a/utils/notes-util/Main.hs b/linters/lint-notes/Main.hs
index aa9386bc01..02ee3f11d4 100644
--- a/utils/notes-util/Main.hs
+++ b/linters/lint-notes/Main.hs
@@ -8,9 +8,9 @@ usage :: IO a
 usage = do
     putStrLn $ unlines
         [ "usage:"
-        , "    ghc-notes <mode>"
-        , "    ghc-notes <mode> @<response-file>"
-        , "    ghc-notes <mode> <file>"
+        , "    lint-notes <mode>"
+        , "    lint-notes <mode> @<response-file>"
+        , "    lint-notes <mode> <file>"
         , ""
         , "valid modes:"
         , "  dump             dump all Note definitions and references"
@@ -51,7 +51,7 @@ main = do
       [mode] -> do
         let excludeList =
               [ "testsuite/tests/linters/notes.stdout"
-              , "utils/notes-util/test" ]
+              , "linters/lint-notes/test" ]
         files <- lines <$> readProcess "git" ["ls-tree", "--name-only", "-r", "HEAD"] ""
         return (parseMode mode, filter (`notElem` excludeList) files)
       _ -> usage
diff --git a/utils/notes-util/Makefile b/linters/lint-notes/Makefile
index 176527a3c7..71500f0147 100644
--- a/utils/notes-util/Makefile
+++ b/linters/lint-notes/Makefile
@@ -10,7 +10,7 @@
 #
 # -----------------------------------------------------------------------------
 
-dir = utils/notes-util
+dir = linters/lint-notes
 TOP = ../..
 include $(TOP)/mk/sub-makefile.mk
 
diff --git a/utils/notes-util/Notes.hs b/linters/lint-notes/Notes.hs
index cf267d8d67..cf267d8d67 100644
--- a/utils/notes-util/Notes.hs
+++ b/linters/lint-notes/Notes.hs
diff --git a/utils/notes-util/check.sh b/linters/lint-notes/check.sh
index acac923471..cd87900f9b 100755..100644
--- a/utils/notes-util/check.sh
+++ b/linters/lint-notes/check.sh
@@ -7,20 +7,20 @@ GHC="${GHC:-ghc}"
 
 cd "$(dirname $0)"
 "$CABAL_INSTALL" build -w "$GHC"
-bin="$("$CABAL_INSTALL" list-bin -w "$GHC" ghc-notes)"
+bin="$("$CABAL_INSTALL" list-bin -w "$GHC" lint-notes)"
 cd "$(git rev-parse --show-toplevel)"
 "$bin" broken-refs \
-    | grep -v "utils/notes-util/expected-broken-note-refs:" \
+    | grep -v "linters/lint-notes/expected-broken-note-refs:" \
     | sed 's/:[0-9]\+:[0-9]\+:/:/' \
     > broken-note-refs
 
-if diff -q utils/notes-util/expected-broken-note-refs broken-note-refs; then
+if diff -q linters/lint-notes/expected-broken-note-refs broken-note-refs; then
     printf "No unexpected broken note references"
 else
     printf "Found unexpected broken note references:\n\n"
-    diff -u utils/notes-util/expected-broken-note-refs broken-note-refs || true
+    diff -u linters/lint-notes/expected-broken-note-refs broken-note-refs || true
     if [[ "$1" == "-a" ]]; then
-        cp broken-note-refs utils/notes-util/expected-broken-note-refs
+        cp broken-note-refs linters/lint-notes/expected-broken-note-refs
         printf "\n"
         printf "Accepted new broken note references."
     else
diff --git a/linters/lint-notes/ghc.mk b/linters/lint-notes/ghc.mk
new file mode 100644
index 0000000000..bd4e97a85f
--- /dev/null
+++ b/linters/lint-notes/ghc.mk
@@ -0,0 +1,18 @@
+# -----------------------------------------------------------------------------
+#
+# (c) 2009 The University of Glasgow
+#
+# This file is part of the GHC build system.
+#
+# To understand how the build system works and how to modify it, see
+#      https://gitlab.haskell.org/ghc/ghc/wikis/building/architecture
+#      https://gitlab.haskell.org/ghc/ghc/wikis/building/modifying
+#
+# -----------------------------------------------------------------------------
+
+linters/lint-notes_USES_CABAL                   = YES
+linters/lint-notes_PACKAGE                      = lint-notes
+linters/lint-notes_dist-install_PROGNAME        = lint-notes
+linters/lint-notes_dist-install_INSTALL         = NO
+linters/lint-notes_dist-install_INSTALL_INPLACE = YES
+$(eval $(call build-prog,linters/lint-notes,dist-install,1))
diff --git a/utils/notes-util/notes-util.cabal b/linters/lint-notes/lint-notes.cabal
index 41b1a5afdd..9896e74766 100644
--- a/utils/notes-util/notes-util.cabal
+++ b/linters/lint-notes/lint-notes.cabal
@@ -1,5 +1,5 @@
 cabal-version:      2.4
-name:               notes-util
+name:               lint-notes
 version:            0.1.0.0
 synopsis:           A tool for querying and checking GHC Notes
 bug-reports: https://gitlab.haskell.org/ghc/ghc
@@ -8,7 +8,7 @@ author:             Ben Gamari
 maintainer:         ben@smart-cactus.org
 copyright:          (c) 2022 Ben Gamari
 
-executable notes-util
+executable lint-notes
     main-is:          Main.hs
     other-modules:    Notes
     build-depends:    base >= 4 && < 5 ,
diff --git a/utils/notes-util/test b/linters/lint-notes/test
index 3eb1e0466e..3eb1e0466e 100644
--- a/utils/notes-util/test
+++ b/linters/lint-notes/test
diff --git a/linters/lint-submodule-refs/Main.hs b/linters/lint-submodule-refs/Main.hs
new file mode 100644
index 0000000000..f99f066da0
--- /dev/null
+++ b/linters/lint-submodule-refs/Main.hs
@@ -0,0 +1,77 @@
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main where
+
+-- base
+import           Control.Monad
+  ( forM, forM_, unless, when )
+import           Data.List
+  ( partition )
+import           Data.Maybe
+  ( mapMaybe )
+import           System.Environment
+  ( getArgs )
+import           System.Exit
+  ( ExitCode(..), exitWith )
+
+-- text
+import qualified Data.Text    as T
+import qualified Data.Text.IO as T
+  ( putStrLn )
+
+-- linters-common
+import           Linters.Common
+  ( GitType(..)
+  , gitBranchesContain, gitCatCommit, gitDiffTree, gitNormCid
+  )
+
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = do
+    dir:refs <- getArgs >>= \case
+        [] -> fail "usage: lint-submodule-refs <git-repo> [<commit-id>+]"
+        x  -> return x
+
+    forM_ (map T.pack refs) $ \ref -> do
+      (cid,deltas) <- gitDiffTree dir ref
+
+      let smDeltas = [ (smPath, smCid) | (_, (GitTypeGitLink, smCid), smPath) <- deltas ]
+
+      unless (null smDeltas) $ do
+          T.putStrLn $ "Submodule update(s) detected in " <> cid <> ":"
+
+          (_, msg) <- gitCatCommit dir cid
+
+          unless ("submodule" `T.isInfixOf` msg) $ do
+              T.putStrLn "*FAIL* commit message does not contain magic 'submodule' word."
+              T.putStrLn "This lint avoids accidental changes to git submodules."
+              T.putStrLn "Include the word 'submodule' in your commit message to silence this warning, e.g. 'Update submodule'."
+              exitWith (ExitFailure 1)
+
+          bad <- fmap or $ forM smDeltas $ \(smPath,smCid) -> do
+              T.putStrLn $ " - " <> smPath <> " => " <> smCid
+
+              let smAbsPath = dir ++ "/" ++ T.unpack smPath
+              remoteBranches <- gitBranchesContain smAbsPath smCid
+
+              let (wip, nonWip) = partition ("wip/" `T.isPrefixOf`) originBranches
+                  originBranches = mapMaybe isOriginTracking remoteBranches
+                  isOriginTracking = T.stripPrefix "origin/"
+              let bad = null nonWip
+              when bad $ do
+                  T.putStrLn $     "   *FAIL* commit not found in submodule repo"
+                  T.putStrLn       "          or not reachable from persistent branches"
+                  T.putStrLn       ""
+                  when (not $ null wip) $ do
+                    T.putStrLn     "     Found the following non-mirrored WIP branches:"
+                    forM_ wip $ \branch -> do
+                      commit <- gitNormCid smAbsPath branch
+                      T.putStrLn $ "      - " <> branch <> " -> " <> commit
+                    T.putStrLn ""
+              pure bad
+
+          if bad
+            then exitWith (ExitFailure 1)
+            else T.putStrLn " OK"
diff --git a/linters/lint-submodule-refs/cabal.project b/linters/lint-submodule-refs/cabal.project
new file mode 100644
index 0000000000..444b636706
--- /dev/null
+++ b/linters/lint-submodule-refs/cabal.project
@@ -0,0 +1,2 @@
+packages: .,
+          ../linters-common
diff --git a/linters/lint-submodule-refs/lint-submodule-refs.cabal b/linters/lint-submodule-refs/lint-submodule-refs.cabal
new file mode 100644
index 0000000000..ce4012adfc
--- /dev/null
+++ b/linters/lint-submodule-refs/lint-submodule-refs.cabal
@@ -0,0 +1,28 @@
+cabal-version:       3.0
+name:                lint-submodule-refs
+version:             0.1.0.0
+synopsis:            Lint submodule references
+license:             GPL-3.0-only
+author:              The GHC team
+build-type:          Simple
+
+executable lint-submodule-refs
+
+  default-language:
+    Haskell2010
+
+  build-depends:
+    base
+       >= 4.14 && < 5,
+    text
+       >= 1.2  && < 2.1,
+    linters-common
+
+  ghc-options:
+    -Wall
+
+  hs-source-dirs:
+    .
+
+  main-is:
+    Main.hs
diff --git a/linters/lint-whitespace/Main.hs b/linters/lint-whitespace/Main.hs
new file mode 100644
index 0000000000..f1657c4f40
--- /dev/null
+++ b/linters/lint-whitespace/Main.hs
@@ -0,0 +1,265 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ViewPatterns #-}
+
+
+module Main where
+
+-- base
+import           Control.Exception
+  ( IOException, handle )
+import           Control.Monad
+  ( forM, forM_, unless, when )
+import           Data.Maybe
+  ( isJust, mapMaybe )
+import           System.Environment
+  ( getArgs )
+import           System.Exit
+  ( ExitCode(..), exitWith )
+
+-- containers
+import Data.Map.Strict
+  ( Map )
+import qualified Data.Map.Strict as Map
+  ( alter, empty, keys, findWithDefault )
+
+-- mtl
+import           Control.Monad.Writer
+  ( liftIO, execWriter, tell )
+
+-- process
+import System.Process
+  ( readProcess )
+
+-- text
+import           Data.Text
+  ( Text )
+import qualified Data.Text    as T
+import qualified Data.Text.IO as T
+  ( readFile )
+
+-- linters-common
+import           Linters.Common
+  ( LintMsg(..), LintLvl(..)
+  , GitType(..)
+  , gitCatBlob, gitDiffTree
+  , z40
+  )
+
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = do
+    getArgs >>= \case
+      ("commits":dir:refs)  -> mainCommits dir refs
+      ("commits":_)         -> fail "usage: lint-whitespace commits <git-repo> [<commit-id>+]"
+      ("files":fs)          -> mainFiles fs
+      ("tracked":args)      -> mainTracked args
+      _ -> fail "usage: lint-whitespace <files|commits|tracked> ..."
+
+mainCommits :: FilePath -> [String] -> IO ()
+mainCommits dir refs = do
+
+    stats <- forM (map T.pack refs) $ \ref -> do
+      (cid,deltas) <- gitDiffTree dir ref
+
+      lintMsgs0 <- forM deltas $ \(origs, (gt, blobId), fname) -> if (gt == GitTypeRegFile && hasSuffix fname)
+        then do
+          let blobIds0 = [ b0 | (GitTypeRegFile, b0, _) <- origs, b0 /= z40 ]
+          blob1  <- gitCatBlob dir blobId
+          blobs0 <- mapM (gitCatBlob dir) blobIds0
+
+          -- blobs0 will be empty in case in case of newly added files as well as renames/copies
+          -- blobs0 will contain more than one entry for merge-commits
+
+          return [ (fname, msg) | msg <- lintBlob blobs0 blob1 ]
+        else return []
+
+      checkLintMsgs ("commit " <> T.unpack cid) lintMsgs0
+
+    finalReport stats
+
+finalReport :: [Maybe LintLvl] -> IO ()
+finalReport stats = do
+    unless (null $ filter isJust stats) $
+        putStrLn "====================================================================================="
+
+    let stats1 = maximum (Nothing : stats)
+
+    -- unless (stats1 == Nothing) $ do
+    --     putStrLn "There were commit message linter issues! For more information see"
+    --     putStrLn ""
+
+    unless (stats1 < Just LintLvlErr) $ do
+        putStrLn "Validation FAILED because at least one commit had linter errors!"
+        exitWith (ExitFailure 1)
+
+    putStrLn "whitespace validation passed!"
+
+checkLintMsgs :: String -> [[(Text, LintMsg)]] -> IO (Maybe LintLvl)
+checkLintMsgs herald lintMsgs0 = do
+      let lintMsgs = concat lintMsgs0
+          status = maximum (Nothing : [ Just lvl | (_, LintMsg lvl _ _ _) <- lintMsgs ])
+          ok     = status < Just LintLvlErr
+
+      unless (null lintMsgs) $ liftIO $ do
+          putStrLn "====================================================================================="
+          putStrLn (herald <> " has whitespace linter issues:")
+          putStrLn ""
+          forM_ lintMsgs $ \(fn, LintMsg lvl lno l m) -> do
+              let lvls = case lvl of
+                      LintLvlErr  -> "*ERROR*"
+                      LintLvlWarn -> "Warning"
+              putStrLn (" " <> lvls <> " " <> T.unpack fn <> ":" <> show lno <> ": " <> T.unpack m)
+              putStrLn (" > " <> show l)
+              putStrLn ""
+              return ()
+
+      unless ok $ liftIO $
+          putStrLn ("Validation FAILED for " <> herald)
+
+      return status
+
+mainFiles :: [FilePath] -> IO ()
+mainFiles fs = do
+  stats <- forM fs $ \f -> do
+    lintMsgs0 <- handle (\(_ :: IOException) -> return []) (lintFile <$> T.readFile f)
+    checkLintMsgs ("file " <> f) [[(T.pack f, err) | err <- lintMsgs0 ]]
+  finalReport stats
+
+mainTracked :: [String] -> IO ()
+mainTracked args = do
+  (ignoredFiles, ignoredDirs) <- parseTrackedArgs args
+  allFiles <- lines <$> readProcess "git" ["ls-tree", "--name-only", "-r", "HEAD"] ""
+  let files = filter (isTracked ignoredFiles ignoredDirs) allFiles
+  mainFiles files
+
+-- Check a file for trailing whitespace and tabs
+lintFile :: Text -> [LintMsg]
+lintFile blob1 = execWriter $ do
+    when (hasTabs blob1) $ do
+        tell [ LintMsg LintLvlErr lno l "introduces TAB"
+             | (lno,l) <- zip [1..] lns
+             , "\t" `T.isInfixOf` l
+             ]
+
+    when (hasTrail blob1) $ do
+        tell [ LintMsg LintLvlErr lno l "introduces trailing whitespace"
+             | (lno,l) <- zip [1..] lns, hasTrail l ]
+  where
+    lns = T.lines blob1
+
+lintBlob :: [Text] -> Text -> [LintMsg]
+lintBlob blobs0 blob1 = execWriter $ do
+    -- Perform simple invariant-preservation checks
+    when (hasTabs blob1 && not (any hasTabs blobs0)) $ do
+        tell [ LintMsg LintLvlErr lno l "introduces TAB"
+             | (lno,l) <- zip [1..] lns
+             , "\t" `T.isInfixOf` l
+             ]
+
+    when (hasTrail blob1 && not (any hasTrail blobs0)) $ do
+        tell [ LintMsg LintLvlErr lno l "introduces trailing whitespace"
+             | (lno,l) <- zip [1..] lns, hasTrail l ]
+
+    when (missingFinalEOL blob1) $ if not (any missingFinalEOL blobs0)
+          then tell [LintMsg LintLvlErr  llno lln "lacking final EOL"]
+          else tell [LintMsg LintLvlWarn llno lln "lacking final EOL"]
+
+  where
+    lns = T.lines blob1
+    llno = length lns
+    lln = case lns of
+        [] -> ""
+        _  -> last lns
+
+hasTabs :: Text -> Bool
+hasTabs = T.any (=='\t')
+
+hasTrail :: Text -> Bool
+hasTrail t = or [ " \n"    `T.isInfixOf`  t
+                , " \r\n"  `T.isInfixOf`  t
+                , "\t\r\n" `T.isInfixOf`  t
+                , " "      `T.isSuffixOf` t
+                , "\t"     `T.isSuffixOf` t
+                ]
+
+missingFinalEOL :: Text -> Bool
+missingFinalEOL = not . T.isSuffixOf "\n"
+
+--------------------------------------------------
+
+data Flag
+  = IgnoreFiles
+  | IgnoreDirs
+  | UnknownFlag Text
+  deriving stock ( Eq, Ord, Show )
+
+parseTrackedArgs :: [String] -> IO ([Text], [Text])
+parseTrackedArgs args = do
+  unless (null bareArgs) $
+    fail "usage: lint-whitespace tracked --ignore-files ... --ignore-dirs ..."
+  unless (null unknownFlags) $
+    fail $ "lint-whitespace tracked: unknown flags " ++ show unknownFlags ++ "\n\
+           \supported flags are --ignore-files and --ignore-dirs"
+  return (ignoredFiles, ignoredDirs)
+  where
+    (bareArgs, flagArgs) = splitOn flagMaybe (map T.pack args)
+    ignoredFiles = Map.findWithDefault [] IgnoreFiles flagArgs
+    ignoredDirs  = Map.findWithDefault [] IgnoreDirs  flagArgs
+    unknownFlags = mapMaybe (\case { UnknownFlag unk -> Just unk ; _ -> Nothing})
+                 $ Map.keys flagArgs
+
+-- Assumes the input string has no whitespace.
+flagMaybe :: Text -> Maybe Flag
+flagMaybe "-f" = Just IgnoreFiles
+flagMaybe "--ignore-files" = Just IgnoreFiles
+flagMaybe "-d" = Just IgnoreDirs
+flagMaybe "--ignore-dirs" = Just IgnoreDirs
+flagMaybe str
+  | let (hyphens, rest) = T.span ((==) '-') str
+  , not (T.null hyphens)
+  = Just (UnknownFlag rest)
+  | otherwise
+  = Nothing
+
+splitOn :: forall a b. Ord b => (a -> Maybe b) -> [a] -> ([a], Map b [a])
+splitOn f = go Nothing
+  where
+    go :: Maybe b -> [a] -> ([a], Map b [a])
+    go _ [] = ([], Map.empty)
+    go mb_b (a:as) = case f a of
+      Nothing ->
+        case go mb_b as of
+          (xs, yxs) ->
+            case mb_b of
+              Nothing -> (a:xs, yxs)
+              Just b  -> (xs, Map.alter (alter_fn a) b yxs)
+      Just b -> go (Just b) as
+    alter_fn :: a -> Maybe [a] -> Maybe [a]
+    alter_fn a Nothing   = Just [a]
+    alter_fn a (Just as) = Just (a:as)
+
+--------------------------------------------------
+-- Predicates used to filter which files we lint.
+
+hasSuffix :: Text -> Bool
+hasSuffix fn = any (`T.isSuffixOf` fn) suffixes
+  where
+    suffixes = T.words ".hs .hsc .lhs .cabal .c .h .lhs-boot .hs-boot .x .y"
+
+autogenFiles :: [ Text ]
+autogenFiles = [ "WCsubst.c", "iconv.c", "Table.hs" ]
+
+ignoredPrefixes :: [Text]
+ignoredPrefixes = [ "testsuite/", "libraries/base/tests"
+                  , "utils/hp2ps", "utils/hpc", "utils/unlit"
+                  ]
+
+isTracked :: [Text] -> [Text] -> FilePath -> Bool
+isTracked ignoredFiles ignoredDirs (T.pack -> fn)
+  =  hasSuffix fn
+  && not (fn `elem` ignoredFiles)
+  && not (any (`T.isPrefixOf` fn) ignoredDirs)
diff --git a/linters/lint-whitespace/cabal.project b/linters/lint-whitespace/cabal.project
new file mode 100644
index 0000000000..444b636706
--- /dev/null
+++ b/linters/lint-whitespace/cabal.project
@@ -0,0 +1,2 @@
+packages: .,
+          ../linters-common
diff --git a/linters/lint-whitespace/ghc.mk b/linters/lint-whitespace/ghc.mk
new file mode 100644
index 0000000000..6b844911e5
--- /dev/null
+++ b/linters/lint-whitespace/ghc.mk
@@ -0,0 +1,18 @@
+# -----------------------------------------------------------------------------
+#
+# (c) 2009 The University of Glasgow
+#
+# This file is part of the GHC build system.
+#
+# To understand how the build system works and how to modify it, see
+#      https://gitlab.haskell.org/ghc/ghc/wikis/building/architecture
+#      https://gitlab.haskell.org/ghc/ghc/wikis/building/modifying
+#
+# -----------------------------------------------------------------------------
+
+linters/lint-whitespace_USES_CABAL                   = YES
+linters/lint-whitespace_PACKAGE                      = lint-whitespace
+linters/lint-whitespace_dist-install_PROGNAME        = lint-whitespace
+linters/lint-whitespace_dist-install_INSTALL         = NO
+linters/lint-whitespace_dist-install_INSTALL_INPLACE = YES
+$(eval $(call build-prog,linters/lint-whitespace,dist-install,1))
diff --git a/linters/lint-whitespace/lint-whitespace.cabal b/linters/lint-whitespace/lint-whitespace.cabal
new file mode 100644
index 0000000000..e3d2aa3a06
--- /dev/null
+++ b/linters/lint-whitespace/lint-whitespace.cabal
@@ -0,0 +1,31 @@
+cabal-version:       3.0
+name:                lint-whitespace
+version:             0.1.0.0
+synopsis:            Lint whitespace
+license:             GPL-3.0-only
+author:              The GHC team
+build-type:          Simple
+
+executable lint-whitespace
+
+  default-language:
+    Haskell2010
+
+  hs-source-dirs:
+    .
+
+  main-is:
+    Main.hs
+
+  build-depends:
+    linters-common,
+    mtl
+      >=2.1 && <2.3,
+    process
+      ^>= 1.6,
+    containers
+      ^>= 0.6,
+    base
+       >= 4.14 && < 5,
+    text
+       >= 1.2  && < 2.1,
diff --git a/linters/linters-common/Linters/Common.hs b/linters/linters-common/Linters/Common.hs
new file mode 100644
index 0000000000..8d92a87787
--- /dev/null
+++ b/linters/linters-common/Linters/Common.hs
@@ -0,0 +1,197 @@
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+
+module Linters.Common where
+
+-- base
+import           Control.Monad
+  ( liftM, unless )
+import           Data.Function
+  ( on )
+import           Data.List
+  ( groupBy )
+import           Data.Maybe
+  ( fromMaybe )
+import           GHC.IO.Encoding
+  ( utf8, setLocaleEncoding, getLocaleEncoding, textEncodingName )
+
+-- deepseq
+import           Control.DeepSeq
+  ( NFData(rnf), force, ($!!) )
+
+-- process
+import System.Process
+  ( readProcess )
+
+-- text
+import           Data.Text
+  ( Text )
+import qualified Data.Text as T
+
+--------------------------------------------------------------------------------
+
+data LintMsg = LintMsg !LintLvl !Int !Text !Text
+              deriving stock Show
+
+data LintLvl = LintLvlWarn | LintLvlErr
+              deriving stock ( Show, Eq, Ord )
+
+type GitRef = Text
+
+type Sh = IO
+
+silently :: a -> a
+silently = id
+
+runGit :: FilePath -> Text -> [Text] -> Sh Text
+runGit fp t ts = runGitStdin fp t ts ""
+
+-- | Run @git@ operation
+runGitStdin :: FilePath -> Text -> [Text] -> Text -> Sh Text
+runGitStdin d op args std_in = do
+    d' <- return $ T.pack d
+    out <- withUtf8 $ silently $ readProcess "git" (map T.unpack ("-C" : d' : op : args)) (T.unpack std_in)
+    return (T.pack out)
+
+-- | WARNING: non-reentrant Hack!
+withUtf8 :: Sh a -> Sh a
+withUtf8 act = do
+    oldloc <- getLocaleEncoding
+    if (textEncodingName oldloc == textEncodingName utf8)
+    then act
+    else do
+        setLocaleEncoding utf8
+        r <- act
+        setLocaleEncoding oldloc
+        return r
+
+-- | wrapper around @git cat-file commit@
+--
+-- Returns (commit-header, commit-body)
+gitCatCommit :: FilePath -> GitRef -> Sh (Text,Text)
+gitCatCommit d ref = do
+    tmp <- runGit d "cat-file" ["commit", ref ]
+    return (fmap (T.drop 2) $ T.breakOn "\n\n" tmp)
+
+-- | wrapper around @git cat-file commit@
+gitCatBlob :: FilePath -> GitRef -> Sh Text
+gitCatBlob d ref = do
+    tmpl <- liftM tread $ runGit d "cat-file" ["-s", ref] -- workaround shelly adding EOLs
+    tmp <- runGit d "cat-file" ["blob", ref]
+    return (T.take tmpl tmp)
+  where
+    tread = read . T.unpack
+
+-- | Wrapper around @git rev-parse --verify@
+--
+-- Normalise git ref to commit sha1
+gitNormCid :: FilePath -> GitRef -> Sh GitRef
+gitNormCid d ref = do
+    tmp <- runGit d "rev-parse" ["-q", "--verify", ref <> "^{commit}" ]
+    return (T.strip tmp)
+
+-- | wrapper around @git branch --contains@
+gitBranchesContain :: FilePath -> GitRef -> Sh [Text]
+gitBranchesContain d ref = do
+    tmp <- liftM T.lines $
+           --errExit False $ print_stderr False $
+           runGit d "branch" ["--contains", ref, "-r"]
+
+    unless (all (\s -> T.take 2 s `elem` ["  ","* "]) tmp) $
+        fail "gitBranchesContain: internal error"
+
+    return $!! map (T.drop 2) tmp
+
+-- | returns @[(path, (url, key))]@
+--
+-- may throw exception
+getModules :: FilePath -> GitRef -> Sh [(Text, (Text, Text))]
+getModules d ref = do
+    tmp <- runGit d "show" [ref <> ":.gitmodules"]
+
+    res <- liftM T.lines $ runGitStdin d "config" [ "--file", "/dev/stdin", "-l" ] tmp
+
+    let ms  = [ (T.tail key1,(key2, T.tail val))
+              | r <- res, "submodule." `T.isPrefixOf` r
+              , let (key,val) = T.break (=='=') r
+              , let (key',key2) = T.breakOnEnd "." key
+              , let (_,key1) = T.break (=='.') (T.init key')
+              ]
+
+        ms' = [ (path', (url, k))
+              | es@((k,_):_) <- groupBy ((==) `on` fst) ms
+              , let props = map snd es
+              , let url = fromMaybe (error "getModules1") (lookup "url" props)
+              , let path' = fromMaybe (error "getModules2") (lookup "path" props)
+              ]
+
+    return $!! ms'
+
+
+{- |
+
+Possible meanings of the 'Char' value:
+
+ * Added (A),
+ * Copied (C),
+ * Deleted (D),
+ * Modified (M),
+ * Renamed (R),
+ * have their type (i.e. regular file, symlink, submodule, ...) changed (T),
+ * are Unmerged (U),
+ * are Unknown (X),
+ * or have had their pairing Broken (B).
+
+-}
+gitDiffTree :: FilePath -> GitRef -> Sh (Text, [([(GitType, Text, Char)], (GitType, Text), Text)])
+gitDiffTree d ref = do
+    tmp <- liftM T.lines $ runGit d "diff-tree" ["--root","-c", "-r", ref]
+    case tmp of
+        cid:deltas -> return $!! (cid, map parseDtLine deltas)
+        []         -> return ("", [])
+
+  where
+    parseDtLine :: Text -> ([(GitType, Text, Char)], (GitType, Text), Text)
+    parseDtLine l
+      | sanityCheck = force (zip3 (map cvtMode mode') oid' (T.unpack k),(cvtMode mode,oid),fp)
+      | otherwise = error "in parseDtLine"
+      where
+        sanityCheck = n > 0 && T.length k == n
+
+        n = T.length cols
+        (mode',mode:tmp') = splitAt n $ T.split (==' ') l''
+        (oid',[oid,k]) = splitAt n tmp'
+        [l'',fp] = T.split (=='\t') l'
+        (cols,l') = T.span (==':') l
+
+gitDiffTreePatch :: FilePath -> GitRef -> Text -> Sh Text
+gitDiffTreePatch d ref fname = runGit d "diff-tree" ["--root", "--cc", "-r", ref, "--", fname]
+
+z40 :: GitRef
+z40 = T.pack (replicate 40 '0')
+
+data GitType
+    = GitTypeVoid
+    | GitTypeRegFile
+    | GitTypeExeFile
+    | GitTypeTree
+    | GitTypeSymLink
+    | GitTypeGitLink
+    deriving stock (Show,Eq,Ord,Enum)
+
+instance NFData GitType where rnf !_ = ()
+
+cvtMode :: Text -> GitType
+cvtMode "000000" = GitTypeVoid
+cvtMode "040000" = GitTypeSymLink
+cvtMode "100644" = GitTypeRegFile
+cvtMode "100755" = GitTypeExeFile
+cvtMode "120000" = GitTypeSymLink
+cvtMode "160000" = GitTypeGitLink
+cvtMode x = error ("cvtMode: " ++ show x)
+
+tshow :: Show a => a -> Text
+tshow = T.pack . show
diff --git a/utils/notes-util/ghc.mk b/linters/linters-common/ghc.mk
index 99f8628b70..409e3c9cc8 100644
--- a/utils/notes-util/ghc.mk
+++ b/linters/linters-common/ghc.mk
@@ -10,9 +10,8 @@
 #
 # -----------------------------------------------------------------------------
 
-utils/notes-util_USES_CABAL                   = YES
-utils/notes-util_PACKAGE                      = notes-util
-utils/notes-util_dist-install_PROGNAME        = notes-util
-utils/notes-util_dist-install_INSTALL         = NO
-utils/notes-util_dist-install_INSTALL_INPLACE = YES
-$(eval $(call build-prog,utils/notes-util,dist-install,1))
+linters/linters-common_USES_CABAL                   = YES
+linters/linters-common_PACKAGE                      = linters-common
+linters/linters-common_dist-install_INSTALL         = YES
+linters/linters-common_dist-install_INSTALL_INPLACE = YES
+$(eval $(call build-package,linters/linters-common,dist-install,1))
diff --git a/linters/linters-common/linters-common.cabal b/linters/linters-common/linters-common.cabal
new file mode 100644
index 0000000000..02245750dd
--- /dev/null
+++ b/linters/linters-common/linters-common.cabal
@@ -0,0 +1,30 @@
+cabal-version:       3.0
+name:                linters-common
+version:             0.1.0.0
+synopsis:            Common library for GHC linting scripts
+license:             GPL-3.0-only
+author:              The GHC team
+build-type:          Simple
+
+library
+  default-language:
+    Haskell2010
+
+  build-depends:
+    process
+      ^>= 1.6,
+    base
+       >= 4.14 && < 5,
+    text
+       >= 1.2  && < 2.1,
+    deepseq
+       >= 1.1,
+
+  hs-source-dirs:
+    .
+
+  ghc-options:
+    -Wall
+
+  exposed-modules:
+    Linters.Common
diff --git a/testsuite/mk/boilerplate.mk b/testsuite/mk/boilerplate.mk
index 9fc9b36e23..03c281f76d 100644
--- a/testsuite/mk/boilerplate.mk
+++ b/testsuite/mk/boilerplate.mk
@@ -231,8 +231,12 @@ ifeq "$(COUNT_DEPS)" ""
 COUNT_DEPS := $(abspath $(TOP)/../inplace/bin/count-deps)
 endif
 
-ifeq "$(NOTES_UTIL)" ""
-NOTES_UTIL := $(abspath $(TOP)/../inplace/bin/notes-util)
+ifeq "$(LINT_NOTES)" ""
+LINT_NOTES := $(abspath $(TOP)/../inplace/bin/lint-notes)
+endif
+
+ifeq "$(LINT_WHITESPACE)" ""
+LINT_WHITESPACE := $(abspath $(TOP)/../inplace/bin/lint-whitespace)
 endif
 
 # -----------------------------------------------------------------------------
diff --git a/testsuite/tests/linters/Makefile b/testsuite/tests/linters/Makefile
index 559d0bba3e..54ef4db132 100644
--- a/testsuite/tests/linters/Makefile
+++ b/testsuite/tests/linters/Makefile
@@ -1,11 +1,96 @@
 TOP=../..
 
-ifeq "$(NOTES_UTIL)" ""
-NOTES_UTIL := $(abspath $(TOP)/../inplace/bin/notes-util)
+ifeq "$(LINT_NOTES)" ""
+LINT_NOTES := $(abspath $(TOP)/../inplace/bin/lint-notes)
+endif
+
+ifeq "$(LINT_WHITESPACE)" ""
+LINT_WHITESPACE := $(abspath $(TOP)/../inplace/bin/lint-whitespace)
 endif
 
 uniques:
 	python3 checkUniques/check-uniques.py $(TOP)/..
 
+makefiles:
+	(cd $(TOP)/tests/linters/ && python3 regex-linters/check-makefiles.py tracked)
+
+version-number:
+	regex-linters/check-version-number.sh ${TOP}/..
+
+cpp:
+	(cd $(TOP)/tests/linters/ && python3 regex-linters/check-cpp.py tracked)
+
+changelogs:
+	regex-linters/check-changelogs.sh $(TOP)/..
+
 notes:
-	(cd $(TOP)/.. && $(NOTES_UTIL) broken-refs)
+	(cd $(TOP)/.. && $(LINT_NOTES) broken-refs)
+
+whitespace:
+	(cd $(TOP)/.. &&\
+	  $(LINT_WHITESPACE) tracked\
+			--ignore-dirs\
+				testsuite\
+				libraries/base/cbits\
+				libraries/base/tests\
+				utils/hp2ps\
+				utils/hpc\
+				utils/unlit\
+			--ignore-files\
+				libraries/base/GHC/IO/Encoding/CodePage/Table.hs\
+				libraries/base/Control/Concurrent/QSem.hs\
+				libraries/base/Control/Concurrent/QSemN.hs\
+				libraries/base/Control/Monad/ST/Imp.hs\
+				libraries/base/Control/Monad/ST/Lazy.hs\
+				libraries/base/Data/Char.hs\
+				libraries/base/Data/Eq.hs\
+				libraries/base/Data/IORef.hs\
+				libraries/base/Data/Int.hs\
+				libraries/base/Data/Ix.hs\
+				libraries/base/Data/Ratio.hs\
+				libraries/base/Data/STRef/Lazy.hs\
+				libraries/base/Data/STRef/Strict.hs\
+				libraries/base/Foreign.hs\
+				libraries/base/Foreign/C.hs\
+				libraries/base/Foreign/Concurrent.hs\
+				libraries/base/Foreign/ForeignPtr.hs\
+				libraries/base/Foreign/ForeignPtr/Imp.hs\
+				libraries/base/Foreign/ForeignPtr/Safe.hs\
+				libraries/base/Foreign/ForeignPtr/Unsafe.hs\
+				libraries/base/Foreign/Marshal.hs\
+				libraries/base/Foreign/Marshal/Alloc.hs\
+				libraries/base/Foreign/Marshal/Error.hs\
+				libraries/base/Foreign/Marshal/Safe.hs\
+				libraries/base/Foreign/Marshal/Unsafe.hs\
+				libraries/base/Foreign/Safe.hs\
+				libraries/base/Foreign/StablePtr.hs\
+				libraries/base/Foreign/Storable.hs\
+				libraries/base/GHC/IO/Encoding/Latin1.hs\
+				libraries/base/GHC/IO/Encoding/Types.hs\
+				libraries/base/GHC/IO/Handle/FD.hs\
+				libraries/base/GHC/IO/IOMode.hs\
+				libraries/base/System/Console/GetOpt.hs\
+				libraries/base/System/IO/Unsafe.hs\
+				libraries/base/System/Mem.hs\
+				libraries/base/Text/Show.hs\
+				libraries/base/include/HsBase.h\
+				libraries/base/include/HsEvent.h\
+				libraries/base/include/md5.h\
+				libraries/ghc-prim/GHC/Tuple.hs\
+				libraries/template-haskell/Language/Haskell/TH/Quote.hs\
+				rts/STM.h\
+				rts/Sparks.h\
+				rts/Threads.h\
+				rts/hooks/OnExit.c\
+				rts/sm/Evac.h\
+				rts/sm/MarkStack.h\
+				rts/sm/MarkWeak.h\
+				rts/sm/Scav.h\
+				rts/sm/Sweep.c\
+				rts/sm/Sweep.h\
+				rts/win32/veh_excn.h\
+				utils/genprimopcode/Parser.y\
+				utils/genprimopcode/Syntax.hs\
+				utils/lndir/lndir-Xos.h\
+				utils/lndir/lndir-Xosdefs.h\
+  )
diff --git a/testsuite/tests/linters/all.T b/testsuite/tests/linters/all.T
index ef3ea5441f..0eefb0f9a4 100644
--- a/testsuite/tests/linters/all.T
+++ b/testsuite/tests/linters/all.T
@@ -14,8 +14,27 @@ def has_ls_files() -> bool:
   except subprocess.CalledProcessError:
     return False
 
+test('makefiles', [ no_deps if has_ls_files() else skip
+                  , extra_files(["regex-linters"]) ]
+                , makefile_test, ['makefiles'])
 
-test('notes', [no_deps if has_ls_files() else skip
-              , req_hadrian_deps(["lint:notes-util"])
+test('changelogs', [ no_deps if has_ls_files() else skip
+                   , extra_files(["regex-linters"]) ]
+                 , makefile_test, ['changelogs'])
+
+test('cpp', [ no_deps if has_ls_files() else skip
+            , extra_files(["regex-linters"]) ]
+            , makefile_test, ['cpp'])
+
+test('version-number', [ no_deps if has_ls_files() else skip
+                       , extra_files(["regex-linters"]) ]
+                     , makefile_test, ['version-number'])
+
+test('notes', [ no_deps if has_ls_files() else skip
+              , req_hadrian_deps(["lint:notes"])
               , normalise_fun(normalise_nos) ]
-              , makefile_test, ['notes'])
+            , makefile_test, ['notes'])
+
+test('whitespace', [ no_deps if has_ls_files() else skip
+                   , req_hadrian_deps(["lint:whitespace"]) ]
+                 , makefile_test, ['whitespace'])
diff --git a/testsuite/tests/linters/changelogs.stdout b/testsuite/tests/linters/changelogs.stdout
new file mode 100644
index 0000000000..9547d7b24b
--- /dev/null
+++ b/testsuite/tests/linters/changelogs.stdout
@@ -0,0 +1 @@
+Changelogs look OK (no "TBA"s, or RELEASE=NO)
diff --git a/testsuite/tests/linters/notes.stdout b/testsuite/tests/linters/notes.stdout
index 8e4ad38ac8..57d2aa1367 100644
--- a/testsuite/tests/linters/notes.stdout
+++ b/testsuite/tests/linters/notes.stdout
@@ -22,11 +22,11 @@ ref    compiler/GHC/Core/Unfold.hs:1242:50:     Note [Unfold info lazy contexts]
 ref    compiler/GHC/Core/Unfold/Make.hs:157:34:     Note [DFunUnfoldings]
 ref    compiler/GHC/Core/Unify.hs:544:16:     Note [Unification result]
 ref    compiler/GHC/Core/Unify.hs:1390:9:     Note [INLINE pragmas and (>>)]
-ref    compiler/GHC/Core/Utils.hs:944:40:     Note [ _       -> [con1]
-ref    compiler/GHC/CoreToStg.hs:460:15:     Note [Nullary unboxed tuple]
-ref    compiler/GHC/Driver/Main.hs:1551:34:     Note [simpleTidyPgm - mkBootModDetailsTc]
-ref    compiler/GHC/Driver/Session.hs:1949:36:     Note [GHC.Driver.Main . Safe Haskell Inference]
-ref    compiler/GHC/Driver/Session.hs:3910:49:     Note [Eta-reduction in -O0]
+ref    compiler/GHC/Core/Utils.hs:947:40:     Note [ _       -> [con1]
+ref    compiler/GHC/CoreToStg.hs:462:15:     Note [Nullary unboxed tuple]
+ref    compiler/GHC/Driver/Main.hs:1566:34:     Note [simpleTidyPgm - mkBootModDetailsTc]
+ref    compiler/GHC/Driver/Session.hs:1947:36:     Note [GHC.Driver.Main . Safe Haskell Inference]
+ref    compiler/GHC/Driver/Session.hs:3916:49:     Note [Eta-reduction in -O0]
 ref    compiler/GHC/Hs/Extension.hs:140:5:     Note [Strict argument type constraints]
 ref    compiler/GHC/HsToCore/Binds.hs:313:33:     Note [AbsBinds wrappers]
 ref    compiler/GHC/HsToCore/Binds.hs:849:46:     Note [Free dictionaries]
@@ -39,8 +39,8 @@ ref    compiler/GHC/HsToCore/Docs.hs:130:0:     Note [1]
 ref    compiler/GHC/HsToCore/Pmc/Solver.hs:853:20:     Note [COMPLETE sets on data families]
 ref    compiler/GHC/HsToCore/Types.hs:61:13:     Note [Generating fresh names for FFI wrappers]
 ref    compiler/GHC/HsToCore/Utils.hs:939:62:     Note [Don't CPR join points]
-ref    compiler/GHC/Iface/Syntax.hs:705:0:     Note [Minimal complete definition]
-ref    compiler/GHC/Iface/Syntax.hs:765:44:     Note [Minimal complete definition]
+ref    compiler/GHC/Iface/Syntax.hs:708:0:     Note [Minimal complete definition]
+ref    compiler/GHC/Iface/Syntax.hs:768:44:     Note [Minimal complete definition]
 ref    compiler/GHC/Parser/Lexer.x:185:7:     Note [Lexing NumericUnderscores extension]
 ref    compiler/GHC/Parser/Lexer.x:502:3:     Note [Lexing NumericUnderscores extension]
 ref    compiler/GHC/Rename/Expr.hs:2013:9:     Note [ApplicativeDo and strict patterns]
@@ -52,10 +52,10 @@ ref    compiler/GHC/Rename/Pat.hs:888:29:     Note [Disambiguating record fields
 ref    compiler/GHC/Rename/Splice.hs:450:27:     Note [Splices]
 ref    compiler/GHC/Runtime/Eval.hs:996:2:     Note [Querying instances for a type]
 ref    compiler/GHC/Runtime/Interpreter.hs:198:30:     Note [uninterruptibleMask_]
-ref    compiler/GHC/StgToCmm.hs:107:18:     Note [codegen-split-init]
-ref    compiler/GHC/StgToCmm.hs:110:18:     Note [pipeline-split-init]
-ref    compiler/GHC/StgToCmm/Expr.hs:491:4:     Note [case on bool]
-ref    compiler/GHC/StgToCmm/Expr.hs:751:3:     Note [alg-alt heap check]
+ref    compiler/GHC/StgToCmm.hs:108:18:     Note [codegen-split-init]
+ref    compiler/GHC/StgToCmm.hs:111:18:     Note [pipeline-split-init]
+ref    compiler/GHC/StgToCmm/Expr.hs:585:4:     Note [case on bool]
+ref    compiler/GHC/StgToCmm/Expr.hs:848:3:     Note [alg-alt heap check]
 ref    compiler/GHC/Tc/Errors.hs:180:13:     Note [Fail fast on kind errors]
 ref    compiler/GHC/Tc/Errors.hs:2016:0:     Note [Highlighting ambiguous type variables]
 ref    compiler/GHC/Tc/Errors/Ppr.hs:1760:11:     Note [Highlighting ambiguous type variables]
@@ -82,10 +82,10 @@ ref    compiler/GHC/Tc/Gen/Pat.hs:1376:16:     Note [Pattern coercions]
 ref    compiler/GHC/Tc/Gen/Sig.hs:78:10:     Note [Overview of type signatures]
 ref    compiler/GHC/Tc/Instance/Family.hs:515:35:     Note [Constrained family instances]
 ref    compiler/GHC/Tc/Module.hs:698:15:     Note [Extra dependencies from .hs-boot files]
-ref    compiler/GHC/Tc/Module.hs:1901:19:     Note [Root-main id]
-ref    compiler/GHC/Tc/Module.hs:1971:6:     Note [Root-main id]
+ref    compiler/GHC/Tc/Module.hs:1904:19:     Note [Root-main id]
+ref    compiler/GHC/Tc/Module.hs:1974:6:     Note [Root-main id]
 ref    compiler/GHC/Tc/Solver.hs:2541:36:     Note [Kind generalisation and SigTvs]
-ref    compiler/GHC/Tc/Solver/Canonical.hs:1228:33:     Note [Canonical LHS]
+ref    compiler/GHC/Tc/Solver/Canonical.hs:1229:33:     Note [Canonical LHS]
 ref    compiler/GHC/Tc/Solver/Interact.hs:1638:9:     Note [No touchables as FunEq RHS]
 ref    compiler/GHC/Tc/Solver/Interact.hs:2292:12:     Note [The equality class story]
 ref    compiler/GHC/Tc/Solver/Rewrite.hs:1032:7:     Note [Stability of rewriting]
@@ -96,9 +96,9 @@ ref    compiler/GHC/Tc/TyCl.hs:4366:16:     Note [rejigCon and c.f. Note [Check
 ref    compiler/GHC/Tc/TyCl/Instance.hs:947:26:     Note [Generalising in tcFamTyPatsGuts]
 ref    compiler/GHC/Tc/Types.hs:647:17:     Note [Generating fresh names for FFI wrappers]
 ref    compiler/GHC/Tc/Types.hs:696:33:     Note [Extra dependencies from .hs-boot files]
-ref    compiler/GHC/Tc/Types.hs:1145:28:     Note [Don't promote data constructors with non-equality contexts]
-ref    compiler/GHC/Tc/Types.hs:1221:36:     Note [Bindings with closed types]
-ref    compiler/GHC/Tc/Types.hs:1457:47:     Note [Care with plugin imports]
+ref    compiler/GHC/Tc/Types.hs:1154:28:     Note [Don't promote data constructors with non-equality contexts]
+ref    compiler/GHC/Tc/Types.hs:1230:36:     Note [Bindings with closed types]
+ref    compiler/GHC/Tc/Types.hs:1466:47:     Note [Care with plugin imports]
 ref    compiler/GHC/Tc/Types/Constraint.hs:238:34:     Note [NonCanonical Semantics]
 ref    compiler/GHC/Tc/Utils/Concrete.hs:246:2:     Note [Concrete and Concrete#]
 ref    compiler/GHC/Tc/Utils/Env.hs:556:7:     Note [Bindings with closed types]
@@ -109,8 +109,8 @@ ref    compiler/GHC/Tc/Utils/TcMType.hs:793:7:     Note [Kind checking for GADTs
 ref    compiler/GHC/Tc/Utils/TcType.hs:529:7:     Note [TyVars and TcTyVars]
 ref    compiler/GHC/ThToHs.hs:1738:11:     Note [Adding parens for splices]
 ref    compiler/GHC/ThToHs.hs:1749:3:     Note [Adding parens for splices]
-ref    compiler/GHC/Types/Basic.hs:586:17:     Note [Safe Haskell isSafeOverlap]
-ref    compiler/GHC/Types/Basic.hs:1326:7:     Note [Activation competition]
+ref    compiler/GHC/Types/Basic.hs:619:17:     Note [Safe Haskell isSafeOverlap]
+ref    compiler/GHC/Types/Basic.hs:1359:7:     Note [Activation competition]
 ref    compiler/GHC/Types/Demand.hs:307:25:     Note [Preserving Boxity of results is rarely a win]
 ref    compiler/GHC/Types/Demand.hs:1100:4:     Note [Use one-shot information]
 ref    compiler/GHC/Types/Error.hs:358:3:     Note [Suppressing Messages]
@@ -124,14 +124,16 @@ ref    compiler/Language/Haskell/Syntax/Expr.hs:1561:32:     Note [Quasi-quote o
 ref    compiler/Language/Haskell/Syntax/Pat.hs:336:12:     Note [Disambiguating record fields]
 ref    configure.ac:212:10:     Note [Linking ghc-bin against threaded stage0 RTS]
 ref    docs/core-spec/core-spec.mng:177:6:     Note [TyBinders]
-ref    ghc/GHCi/UI.hs:3630:25:     Note [ModBreaks.decls]
+ref    ghc/GHCi/UI.hs:3646:25:     Note [ModBreaks.decls]
 ref    ghc/ghc.mk:62:6:     Note [Linking ghc-bin against threaded stage0 RTS]
 ref    hadrian/src/Expression.hs:130:30:     Note [Linking ghc-bin against threaded stage0 RTS]
 ref    libraries/base/GHC/ST.hs:139:7:     Note [Definition of runRW#]
+ref    linters/lint-notes/Notes.hs:32:29:     Note [" <> T.unpack x <> "]
+ref    linters/lint-notes/Notes.hs:69:22:     Note [...]
 ref    testsuite/config/ghc:212:10:     Note [WayFlags]
 ref    testsuite/driver/testlib.py:152:10:     Note [Why is there no stage1 setup function?]
 ref    testsuite/driver/testlib.py:156:2:     Note [Why is there no stage1 setup function?]
-ref    testsuite/mk/boilerplate.mk:259:2:     Note [WayFlags]
+ref    testsuite/mk/boilerplate.mk:263:2:     Note [WayFlags]
 ref    testsuite/tests/indexed-types/should_fail/ExtraTcsUntch.hs:30:27:     Note [Extra TcS Untouchables]
 ref    testsuite/tests/perf/join_points/join005.hs:19:63:     Note [Don't CPR join points]
 ref    testsuite/tests/perf/should_run/all.T:3:6:     Note [Solving from instances when interacting Dicts]
@@ -149,7 +151,5 @@ ref    testsuite/tests/typecheck/should_compile/tc228.hs:9:7:     Note [Inferenc
 ref    testsuite/tests/typecheck/should_compile/tc231.hs:12:16:     Note [Important subtlety in oclose]
 ref    testsuite/tests/typecheck/should_fail/UnliftedNewtypesMultiFieldGadt.hs:11:28:     Note [Kind-checking the field type]
 ref    testsuite/tests/typecheck/should_fail/tcfail093.hs:13:7:     Note [Important subtlety in oclose]
-ref    utils/notes-util/Notes.hs:33:29:     Note [" <> T.unpack x <> "]
-ref    utils/notes-util/Notes.hs:70:22:     Note [...]
-ref    validate:413:14:     Note [Why is there no stage1 setup function?]
+ref    validate:412:14:     Note [Why is there no stage1 setup function?]
 
diff --git a/testsuite/tests/linters/regex-linters/check-changelogs.sh b/testsuite/tests/linters/regex-linters/check-changelogs.sh
new file mode 100755
index 0000000000..10fca9d5c0
--- /dev/null
+++ b/testsuite/tests/linters/regex-linters/check-changelogs.sh
@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+set -e
+
+COLOR_RED="\e[31m"
+COLOR_GREEN="\e[32m"
+COLOR_NONE="\e[0m"
+
+if grep -E -q 'RELEASE=YES' ${1}/configure.ac && grep TBA ${1}/libraries/*/changelog.md
+then
+    echo -e "${COLOR_RED}Error: Found \"TBA\"s in changelogs.${COLOR_NONE}"
+    exit 1
+else
+    echo -e "${COLOR_GREEN}Changelogs look OK (no \"TBA\"s, or RELEASE=NO)${COLOR_NONE}"
+    exit 0
+fi
diff --git a/.gitlab/linters/check-cpp.py b/testsuite/tests/linters/regex-linters/check-cpp.py
index ffa430e10d..4cc2257984 100755..100644
--- a/.gitlab/linters/check-cpp.py
+++ b/testsuite/tests/linters/regex-linters/check-cpp.py
@@ -37,6 +37,8 @@ for l in linters:
         'images'))
     # Don't lint core spec
     l.add_path_filter(lambda path: not path.name == 'core-spec.pdf')
+    # Don't lint the linter itself
+    l.add_path_filter(lambda path: not path.name == 'check-cpp.py')
 
 if __name__ == '__main__':
     run_linters(linters)
diff --git a/.gitlab/linters/check-makefiles.py b/testsuite/tests/linters/regex-linters/check-makefiles.py
index 5a8286c6a7..5a8286c6a7 100755..100644
--- a/.gitlab/linters/check-makefiles.py
+++ b/testsuite/tests/linters/regex-linters/check-makefiles.py
diff --git a/.gitlab/linters/check-version-number.sh b/testsuite/tests/linters/regex-linters/check-version-number.sh
index 4f478e487a..2ce68627f4 100755
--- a/.gitlab/linters/check-version-number.sh
+++ b/testsuite/tests/linters/regex-linters/check-version-number.sh
@@ -2,6 +2,6 @@
 
 set -e
 
-grep -E -q 'RELEASE=NO' configure.ac ||
-  grep -E -q '\[[0-9]+\.[0-9]+\.[0-9]+\]' configure.ac ||
+grep -E -q 'RELEASE=NO' ${1}/configure.ac ||
+  grep -E -q '\[[0-9]+\.[0-9]+\.[0-9]+\]' ${1}/configure.ac ||
   ( echo "error: configure.ac: GHC version number must have three components when RELEASE=YES."; exit 1 )
diff --git a/.gitlab/linters/linter.py b/testsuite/tests/linters/regex-linters/linter.py
index 61fe18de33..2246dcce30 100644
--- a/.gitlab/linters/linter.py
+++ b/testsuite/tests/linters/regex-linters/linter.py
@@ -38,6 +38,12 @@ def get_changed_files(base_commit: str, head_commit: str,
     files = subprocess.check_output(cmd)
     return files.decode('UTF-8').split('\n')
 
+def get_tracked_files(subdir: str = '.'):
+    """ Get the files tracked by git in the given subdirectory. """
+    cmd = ['git', 'ls-tree', '--name-only', '-r', 'HEAD', subdir]
+    files = subprocess.check_output(cmd)
+    return files.decode('UTF-8').split('\n')
+
 Warning = namedtuple('Warning', 'path,line_no,line_content,message')
 
 class Linter(object):
@@ -106,15 +112,19 @@ def run_linters(linters: Sequence[Linter],
     subparser.set_defaults(get_linted_files=lambda args:
                             get_changed_files(args.base, args.head, subdir))
 
-    subparser = subparsers.add_parser('files', help='Lint a range of commits')
+    subparser = subparsers.add_parser('files', help='Lint the given files')
     subparser.add_argument('file', nargs='+', help='File to lint')
     subparser.set_defaults(get_linted_files=lambda args: args.file)
 
+    subparser = subparsers.add_parser('tracked', help="Lint files tracked by Git")
+    subparser.set_defaults(get_linted_files=lambda args:
+                            get_tracked_files(subdir))
+
     args = parser.parse_args()
 
     linted_files = args.get_linted_files(args)
     for path in linted_files:
-        if path.startswith('.gitlab/linters'):
+        if path.startswith('linters'):
             continue
         for linter in linters:
             linter.do_lint(Path(path))
diff --git a/testsuite/tests/linters/whitespace.stdout b/testsuite/tests/linters/whitespace.stdout
new file mode 100644
index 0000000000..b773a1831d
--- /dev/null
+++ b/testsuite/tests/linters/whitespace.stdout
@@ -0,0 +1 @@
+whitespace validation passed!