Add shell and build environment for NixOS

mk/depends.mk

@@ -3,10 +3,15 @@
 # Don't check for Rust/Cargo if you will be using Podman
 ifneq ($(PODMAN_BUILD),1)
 
+# don’t check for Rust and Cargo if building on a Nix system
+ifneq ($(NIX_SHELL_BUILD),1)
+
 ifeq ($(shell which rustup),)
 $(error rustup not found, install from "https://rustup.rs/")
 endif
 
+endif
+
 ifeq ($(shell which cbindgen),)
 $(error cbindgen not found, install from crates.io or from your package manager)
 endif
@@ -19,9 +24,11 @@ ifeq ($(shell which just),)
 $(error 'just' not found, install from crates.io or from your package manager)
 endif
 
+ifneq ($(NIX_SHELL_BUILD),1)
 CARGO_CONFIG_VERSION=0.1.1
 ifeq ($(shell env -u RUSTUP_TOOLCHAIN cargo install --list | grep '^cargo-config v$(CARGO_CONFIG_VERSION):$$'),)
 $(error cargo-config $(CARGO_CONFIG_VERSION) not found, run "cargo install --force --version $(CARGO_CONFIG_VERSION) cargo-config")
 endif
+endif
 
 endif

mk/fstools.mk

@@ -16,6 +16,9 @@ else
 	touch $@
 endif
 
+$(INSTALLER): CC = 
+$(INSTALLER): TARGET = $(HOST_TARGET)
+$(INSTALLER): RUSTUP_TOOLCHAIN = 
 $(INSTALLER): installer
 	$(HOST_CARGO) build --bin redox_installer --manifest-path installer/Cargo.toml --release