More granular file resolving function, add back warnings

src/Stack/Package.hs

@@ -804,11 +804,17 @@ resolveComponentFiles component build names = do
 -- | Get all C sources and extra source files in a build.
 buildOtherSources :: BuildInfo -> RIO Ctx [DotCabalPath]
 buildOtherSources build = do
+    cwd <- liftIO getCurrentDir
     dir <- asks (parent . ctxFile)
-    -- TODO: add warnMissing here too
+    file <- asks ctxFile
     csources <-
-        forMaybeM (cSources build) $ \fp ->
-            findCandidate [dir] (DotCabalCFile fp)
+        forMaybeM (cSources build) $ \fp -> do
+            result <- resolveDirFile dir fp
+            case result of
+              Nothing -> do
+                warnMissingFile "File" cwd fp file
+                return Nothing
+              Just p -> return $ Just (DotCabalCFilePath p)
     jsources <-
         forMaybeM (targetJsSources build) $ \fp ->
             findCandidate [dir] (DotCabalFile fp)
@@ -1231,14 +1237,16 @@ findCandidate dirs name = do
 
                   -- Otherwise, return everything
                   (xs, ys) -> xs ++ ys
-    resolveCandidate
-        :: (MonadIO m, MonadThrow m)
-        => Path Abs Dir -> FilePath.FilePath -> m [Path Abs File]
-    resolveCandidate x y = do
-        -- The standard canonicalizePath does not work for this case
-        p <- parseCollapsedAbsFile (toFilePath x FilePath.</> y)
-        exists <- doesFileExist p
-        return $ if exists then [p] else []
+    resolveCandidate dir = fmap maybeToList . resolveDirFile dir
+
+resolveDirFile
+    :: (MonadIO m, MonadThrow m)
+    => Path Abs Dir -> FilePath.FilePath -> m (Maybe (Path Abs File))
+resolveDirFile x y = do
+    -- The standard canonicalizePath does not work for this case
+    p <- parseCollapsedAbsFile (toFilePath x FilePath.</> y)
+    exists <- doesFileExist p
+    return $ if exists then Just p else Nothing
 
 -- | Warn the user that multiple candidates are available for an
 -- entry, but that we picked one anyway and continued.
@@ -1315,16 +1323,19 @@ resolveOrWarn subject resolver path =
      file <- asks ctxFile
      dir <- asks (parent . ctxFile)
      result <- resolver dir path
-     when (isNothing result) $
-       prettyWarnL
-           [ fromString . T.unpack $ subject -- TODO: needs style?
-           , flow "listed in"
-           , maybe (pretty file) pretty (stripProperPrefix cwd file)
-           , flow "file does not exist:"
-           , style Dir . fromString $ path
-           ]
+     when (isNothing result) $ warnMissingFile subject cwd path file
      return result
 
+warnMissingFile :: Text -> Path Abs Dir -> FilePath -> Path Abs File -> RIO Ctx ()
+warnMissingFile subject cwd path fromFile =
+    prettyWarnL
+        [ fromString . T.unpack $ subject -- TODO: needs style?
+        , flow "listed in"
+        , maybe (pretty fromFile) pretty (stripProperPrefix cwd fromFile)
+        , flow "file does not exist:"
+        , style Dir . fromString $ path
+        ]
+
 -- | Resolve the file, if it can't be resolved, warn for the user
 -- (purely to be helpful).
 resolveFileOrWarn :: FilePath.FilePath