[#164] Use only '/' as path separator

Problem: in markdown links, '/' should always be used as path separator ,
e.g. GitHub renderer is not threating link `[x](a\b.md)` as a link
to file in dir `a`
We use OS-dependent file separators everywhere, so
e.g. `canonizeLocalRef "./a.md"="./a.md`"` on Windows

Solution: replace '\' to '/' while constructing repo tree if needed
and then use only '/', preferring functions from `System.FilePath.Posix`.
We can do this, since 'a/b' and `a\b` are equivalent paths on Windows

src/Xrefcheck/Core.hs

@@ -21,7 +21,7 @@ import Data.Map qualified as M
 import Data.Reflection (Given)
 import Data.Text qualified as T
 import Fmt (Buildable (..), blockListF, blockListF', nameF, (+|), (|+))
-import System.FilePath (isPathSeparator, pathSeparator)
+import System.FilePath.Posix (isPathSeparator)
 import Time (Second, Time)
 
 import Data.DList (DList)
@@ -303,7 +303,7 @@ canonizeLocalRef :: Text -> Text
 canonizeLocalRef ref =
   maybe ref canonizeLocalRef (T.stripPrefix localPrefix ref)
   where
-    localPrefix = toText ['.', pathSeparator]
+    localPrefix = "./"
 
 -----------------------------------------------------------
 -- Visualisation

src/Xrefcheck/Scan.hs

@@ -30,7 +30,9 @@ import Data.Reflection (Given)
 import Fmt (Buildable (..), nameF, (+|), (|+))
 import System.Directory (doesDirectoryExist)
 import System.Directory.Tree qualified as Tree
-import System.FilePath (dropTrailingPathSeparator, equalFilePath, takeDirectory, takeExtension)
+import System.FilePath qualified as OsDependentFilePath
+import System.FilePath.Posix
+  (dropTrailingPathSeparator, equalFilePath, takeDirectory, takeExtension)
 
 import Xrefcheck.Core
 import Xrefcheck.Progress
@@ -118,15 +120,17 @@ scanRepo rw formatsSupport config root = do
 
   _ Tree.:/ repoTree <- liftIO $ Tree.readDirectoryWithL processFile root
   let (errs, fileInfos) = gatherScanErrs &&& gatherFileInfos
-        $ dropSndMaybes . F.toList
+        $ map (first useLinuxPathSep) . dropSndMaybes . F.toList
         $ Tree.zipPaths $ location Tree.:/ repoTree
   return . ScanResult errs $ RepoInfo (M.fromList fileInfos)
   where
     isDirectory = readingSystem . doesDirectoryExist
     gatherScanErrs = foldMap (snd . snd)
     gatherFileInfos = map (bimap normaliseWithNoTrailing fst)
+    useLinuxPathSep | OsDependentFilePath.pathSeparator == '/' = id
+                    | otherwise = intercalate "/" . OsDependentFilePath.splitDirectories
 
-    processFile file = do
+    processFile (useLinuxPathSep -> file) = do
       let ext = takeExtension file
       let mscanner = formatsSupport ext
       if isIgnored file

src/Xrefcheck/System.hs

@@ -20,8 +20,9 @@ import Data.Coerce (coerce)
 import GHC.IO.Unsafe (unsafePerformIO)
 import System.Directory (canonicalizePath)
 import System.Environment (lookupEnv)
-import System.FilePath ((</>))
 import System.FilePath.Glob qualified as Glob
+import System.FilePath.Posix ((</>))
+
 import Xrefcheck.Util (normaliseWithNoTrailing)
 
 -- | We can quite safely treat surrounding filesystem as frozen,

src/Xrefcheck/Util.hs

@@ -26,7 +26,7 @@ import Data.Time (UTCTime)
 import Data.Time.Clock (nominalDiffTimeToSeconds)
 import Data.Time.Clock.POSIX (POSIXTime, utcTimeToPOSIXSeconds)
 import Fmt (Builder)
-import System.FilePath (dropTrailingPathSeparator, normalise)
+import System.FilePath.Posix (dropTrailingPathSeparator, normalise)
 import Time (Second, Time (..), sec)
 
 import Xrefcheck.Util.Colorize

src/Xrefcheck/Verify.hs

@@ -58,7 +58,7 @@ import Network.HTTP.Req
 import Network.HTTP.Types.Header (hRetryAfter)
 import Network.HTTP.Types.Status (Status, statusCode, statusMessage)
 import System.Directory (doesDirectoryExist, doesFileExist)
-import System.FilePath (makeRelative, normalise, splitDirectories, takeDirectory, (</>))
+import System.FilePath.Posix (makeRelative, normalise, splitDirectories, takeDirectory, (</>))
 import Text.ParserCombinators.ReadPrec qualified as ReadPrec (lift)
 import Text.Regex.TDFA.Text (Regex, regexec)
 import Text.URI (Authority (..), ParseExceptionBs, URI (..), mkURIBs)