refactor how nim compiler is provided in nix

nix/default.nix

@@ -2,8 +2,6 @@
 
 let
   deps      = import ./deps.nix    { inherit pkgs; };
-  nimSrc    = pkgs.callPackage ./nim.nix    {};
-  nimbleSrc = pkgs.callPackage ./nimble.nix {};
 
   # nat_traversal is excluded from the static pathArgs; it is handled
   # separately in buildPhase (its bundled C libs must be compiled first).
@@ -62,8 +60,6 @@ pkgs.stdenv.mkDerivation {
       ${pathArgs} \
       --path:$NAT_TRAV \
       --path:$NAT_TRAV/src \
-      --lib:${nimSrc}/lib \
-      --nimblePath:${nimbleSrc} \
       --passL:"-L${zerokitRln}/lib -lrln" \
       --define:disable_libbacktrace \
       --out:build/liblogosdelivery.${libExt} \
@@ -83,8 +79,6 @@ pkgs.stdenv.mkDerivation {
       ${pathArgs} \
       --path:$NAT_TRAV \
       --path:$NAT_TRAV/src \
-      --lib:${nimSrc}/lib \
-      --nimblePath:${nimbleSrc} \
       --passL:"-L${zerokitRln}/lib -lrln" \
       --define:disable_libbacktrace \
       --out:build/liblogosdelivery.a \

nix/nim.nix

@@ -1,19 +0,0 @@
-# Fetches the Nim source tree at the exact revision declared in waku.nimble.
-# The compiler binary is still pkgs.nim-2_2 (pre-built); this source is
-# used to pin the stdlib to the same commit.
-# Regenerate sha256 with:
-#   nix shell nixpkgs#nix-prefetch-git --command \
-#     nix-prefetch-git --url https://github.com/nim-lang/Nim.git --rev v<version> --fetch-submodules
-{ pkgs }:
-let
-  lines       = pkgs.lib.splitString "\n" (builtins.readFile ../waku.nimble);
-  versionLine = builtins.head (builtins.filter
-    (l: builtins.match "^const NimVersion.*" l != null) lines);
-  version     = builtins.head (builtins.match ".*\"([0-9]+\\.[0-9]+\\.[0-9]+)\".*" versionLine);
-in
-pkgs.fetchgit {
-  url = "https://github.com/nim-lang/Nim.git";
-  rev = "v${version}";
-  sha256 = "1g4nxbwbc6h174gbpa3gcs47xwk6scbmiqlp0nq1ig3af8fcqcnj";
-  fetchSubmodules = true;
-}

nix/nimble.nix

@@ -1,17 +0,0 @@
-# Fetches Nimble at the exact revision declared in waku.nimble.
-# Regenerate hash with:
-#   nix store prefetch-file --hash-type sha256 --unpack \
-#     https://github.com/nim-lang/nimble/archive/v<version>.tar.gz
-# or set hash = "" and let Nix report the correct value.
-{ pkgs }:
-let
-  lines       = pkgs.lib.splitString "\n" (builtins.readFile ../waku.nimble);
-  versionLine = builtins.head (builtins.filter
-    (l: builtins.match "^const NimbleVersion.*" l != null) lines);
-  version     = builtins.head (builtins.match ".*\"([0-9]+\\.[0-9]+\\.[0-9]+)\".*" versionLine);
-in
-pkgs.fetchgit {
-  url  = "https://github.com/nim-lang/nimble";
-  rev  = "v${version}";
-  hash = "sha256-wgzFhModFkwB8st8F5vSkua7dITGGC2cjoDvgkRVZMs=";
-}

nix/shell.nix

@@ -14,6 +14,7 @@ pkgs.mkShell {
     rustup
     rustc
     cmake
-    nim-unwrapped-2_2
+    nim-2_2
+    nimble
   ];
 }