lib.replaceChars: warn about being a deprecated alias

replaceStrings has been in nix since 2015(nix 1.10)

so it is safe to remove the fallback

d6d5885c15

nixos/lib/systemd-lib.nix

@@ -8,9 +8,9 @@ let
   systemd = cfg.package;
 in rec {
 
-  shellEscape = s: (replaceChars [ "\\" ] [ "\\\\" ] s);
+  shellEscape = s: (replaceStrings [ "\\" ] [ "\\\\" ] s);
 
-  mkPathSafeName = lib.replaceChars ["@" ":" "\\" "[" "]"] ["-" "-" "-" "" ""];
+  mkPathSafeName = lib.replaceStrings ["@" ":" "\\" "[" "]"] ["-" "-" "-" "" ""];
 
   # a type for options that take a unit name
   unitNameType = types.strMatching "[a-zA-Z0-9@%:_.\\-]+[.](service|socket|device|mount|automount|swap|target|path|timer|scope|slice)";
@@ -258,7 +258,7 @@ in rec {
 
   makeJobScript = name: text:
     let
-      scriptName = replaceChars [ "\\" "@" ] [ "-" "_" ] (shellEscape name);
+      scriptName = replaceStrings [ "\\" "@" ] [ "-" "_" ] (shellEscape name);
       out = (pkgs.writeShellScriptBin scriptName ''
         set -e
         ${text}

nixos/lib/utils.nix

@@ -48,7 +48,7 @@ rec {
     trim = s: removeSuffix "/" (removePrefix "/" s);
     normalizedPath = strings.normalizePath s;
   in
-    replaceChars ["/"] ["-"]
+    replaceStrings ["/"] ["-"]
     (replacePrefix "." (strings.escapeC ["."] ".")
     (strings.escapeC (stringToCharacters " !\"#$%&'()*+,;<=>=@[\\]^`{|}~-")
     (if normalizedPath == "/" then normalizedPath else trim normalizedPath)));
@@ -67,7 +67,7 @@ rec {
         else if builtins.isInt arg || builtins.isFloat arg then toString arg
         else throw "escapeSystemdExecArg only allows strings, paths and numbers";
     in
-      replaceChars [ "%" "$" ] [ "%%" "$$" ] (builtins.toJSON s);
+      replaceStrings [ "%" "$" ] [ "%%" "$$" ] (builtins.toJSON s);
 
   # Quotes a list of arguments into a single string for use in a Exec*
   # line.
@@ -112,7 +112,7 @@ rec {
         else if isAttrs item then
           map (name:
             let
-              escapedName = ''"${replaceChars [''"'' "\\"] [''\"'' "\\\\"] name}"'';
+              escapedName = ''"${replaceStrings [''"'' "\\"] [''\"'' "\\\\"] name}"'';
             in
               recurse (prefix + "." + escapedName) item.${name}) (attrNames item)
         else if isList item then