substituteAll: validate arguments

So no one can repeat my mistakes.

pkgs/build-support/substitute/substitute-all.nix

@@ -1,12 +1,22 @@
-{ stdenvNoCC }:
+{ lib, stdenvNoCC }:
-
-args:
-
 # see the substituteAll in the nixpkgs documentation for usage and constraints
-stdenvNoCC.mkDerivation ({
+args:
-  name = if args ? name then args.name else baseNameOf (toString args.src);
+let
-  builder = ./substitute-all.sh;
+  # keep this in sync with substituteAll
-  inherit (args) src;
+  isInvalidArgName = x: builtins.match "^[a-z][a-zA-Z0-9_]*$" x == null;
-  preferLocalBuild = true;
+  invalidArgs = builtins.filter isInvalidArgName (builtins.attrNames args);
-  allowSubstitutes = false;
+in
-} // args)
+  if invalidArgs == [] then
+    stdenvNoCC.mkDerivation ({
+      name = if args ? name then args.name else baseNameOf (toString args.src);
+      builder = ./substitute-all.sh;
+      inherit (args) src;
+      preferLocalBuild = true;
+      allowSubstitutes = false;
+    } // args)
+  else throw ''
+    Argument names for `pkgs.substituteAll` must:
+      - start with a lower case ASCII letter
+      - only contain ASCII letters, digits and underscores
+    Found invalid argument names: ${lib.concatStringsSep ", " invalidArgs}.
+  ''