lib.strings.normalizePath: Deprecate for path values

There's no need to call this function on path data types, and it's
confusing with the new lib.path library functions

1 files changed, 14 insertions, 1 deletions

diff --git a/lib/strings.nix b/lib/strings.nix
index 963d937947f2b..be4e8ece59361 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -207,7 +207,20 @@ rec {
        normalizePath "/a//b///c/"
        => "/a/b/c/"
   */
-  normalizePath = s: (builtins.foldl' (x: y: if y == "/" && hasSuffix "/" x then x else x+y) "" (stringToCharacters s));
+  normalizePath = s:
+    warnIf
+      (isPath s)
+      ''
+        lib.strings.normalizePath: The argument (${toString s}) is a path value, but only strings are supported.
+            Path values are always normalised in Nix, so there's no need to call this function on them.
+            This function also copies the path to the Nix store and returns the store path, the same as "''${path}" will, which may not be what you want.
+            This behavior is deprecated and will throw an error in the future.''
+      (
+        builtins.foldl'
+          (x: y: if y == "/" && hasSuffix "/" x then x else x+y)
+          ""
+          (stringToCharacters s)
+      );
 
   /* Depending on the boolean `cond', return either the given string
      or the empty string. Useful to concatenate against a bigger string.