nix: bundle a rust nightly channel manifest for Hydra restrict-eval being always-on

default.nix

@@ -1,10 +1,19 @@
-let
-  mozillaOverlay = import <mozillaOverlay>;
-  pkgs = import <nixpkgs> { overlays = [ mozillaOverlay ]; };
-in
+{ # Use master branch of the overlay by default
+  mozillaOverlay ? import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz),
+  # This is needed when nix-build is run with option
+  # `restrict-eval`. Setting this flag to `true` causes the
+  # rustPlatform to be generated from the bundled
+  # `channel-rust-nightly.toml`. By default (`false`) the
+  # mozillaOverlay fetches the latest manifest.
+  rustRestrictedManifest ? false,
+  pkgs ? import <nixpkgs> { overlays = [ mozillaOverlay ]; },
+}:
+
 with pkgs;
 let
-  rustPlatform = recurseIntoAttrs (callPackage (import ./nix/rustPlatform.nix) {});
+  rustPlatform = recurseIntoAttrs (callPackage (import ./nix/rustPlatform.nix) {
+    restrictedManifest = rustRestrictedManifest;
+  });
   adc2tcp = callPackage (import ./nix/adc2tcp.nix) { inherit rustPlatform; };
   openocd = callPackage (import ./nix/openocd.nix) {};
 in

nix/rustPlatform.nix

@@ -1,14 +1,27 @@
-{ recurseIntoAttrs, makeRustPlatform, rustChannelOfTargets, rustChannel ? "nightly" }:
+{ recurseIntoAttrs, stdenv, lib,
+  makeRustPlatform, rustChannelOfTargets,
+  fetchurl, patchelf,
+  restrictedManifest ? false
+}:
 
 let
   targets = [
     # "x86_64-unknown-linux-gnu"
     # "thumbv6m-none-eabi"
+    # "thumbv7m-none-eabi"
     # "thumbv7em-none-eabi"
     "thumbv7em-none-eabihf"
   ];
-  rust = builtins.trace "rustChannel: selected channel ${rustChannel}"
-    rustChannelOfTargets rustChannel null targets;
+  rustChannel =
+    lib.rustLib.fromManifestFile ./channel-rust-nightly.toml {
+      inherit stdenv fetchurl patchelf;
+    };
+  rust =
+    if restrictedManifest
+    then
+      rustChannel.rust.override { inherit targets; }
+    else
+      rustChannelOfTargets "nightly" null targets;
 in
 makeRustPlatform {
   rustc = rust;

release.nix

@@ -0,0 +1,6 @@
+# For running on Hydra
+
+import ./default.nix {
+  mozillaOverlay = import <mozillaOverlay>;
+  rustRestrictedManifest = true;
+}