Add support for legacy rust-toolchain

Change to immutable URLs

README.md

@@ -87,9 +87,9 @@ Here's an example of using it in nixos configuration.
  distRoot = "https://static.rust-lang.org/dist";
 
  # Select a toolchain and aggregate components by rustup's `rust-toolchain` file format.
- # See: https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file
+ # See: https://github.com/ebroto/rustup/blob/c2db7dac6b38c99538eec472db9d23d18f918409/README.md#the-toolchain-file
  fromRustupToolchain = { channel, components ? [], targets ? [] }: «derivation»;
- # Same as `fromRustupToolchain` but read from a `rust-toolchain` TOML file.
+ # Same as `fromRustupToolchain` but read from a `rust-toolchain` file (legacy one-line string or in TOML).
  fromRustupToolchainFile = rust-toolchain-file-path: «derivation»;
 
  stable = {

flake.nix

@@ -96,12 +96,16 @@
  extensions = [ "rustfmt-preview" "rustc-dev" ];
  targets = [ "wasm32-unknown-unknown" "aarch64-unknown-linux-gnu" ];
  });
- rustup-toolchain-customization-file = assertEq
- (fromRustupToolchainFile ./tests/rust-toolchain)
+
+ rustup-toolchain-file-toml = assertEq
+ (fromRustupToolchainFile ./tests/rust-toolchain-toml)
  (nightly."2020-07-10".rust.override {
  extensions = [ "rustfmt-preview" "rustc-dev" ];
  targets = [ "wasm32-unknown-unknown" "aarch64-unknown-linux-gnu" ];
  });
+ rustup-toolchain-file-legacy = assertEq
+ (fromRustupToolchainFile ./tests/rust-toolchain-legacy)
+ nightly."2020-07-10".rust;
  };
 
  checkDrvs = {};

rust-overlay.nix

@@ -34,13 +34,22 @@ let
  else throw "Unknown channel: ${channel}";
 
  # Select a toolchain and aggregate components by rustup's `rust-toolchain` file format.
- # See: https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file
+ # See: https://github.com/ebroto/rustup/blob/c2db7dac6b38c99538eec472db9d23d18f918409/README.md#the-toolchain-file
  fromRustupToolchain = { channel, components ? [], targets ? [] }:
  (toolchainFromManifest (selectManifest { inherit channel; })).rust.override {
  extensions = components;
  inherit targets;
  };
 
+ # Same as `fromRustupToolchain` but read from a `rust-toolchain` file (legacy one-line string or in TOML).
+ fromRustupToolchainFile = path: let
+ inherit (builtins) readFile match fromTOML head;
+ content = readFile path;
+ legacy = match "([^\r\n]+)\r?\n?" content;
+ in if legacy != null
+ then fromRustupToolchain { channel = head legacy; }
+ else fromRustupToolchain (fromTOML content).toolchain;
+
  getComponentsWithFixedPlatform = pkgs: pkgname: stdenv:
  let
  pkg = pkgs.${pkgname};
@@ -315,8 +324,7 @@ in {
  (super.rust-bin or {}) //
  mapAttrs (channel: mapAttrs (version: toolchainFromManifest)) super.rust-bin.manifests //
  {
- fromRustupToolchainFile = path: fromRustupToolchain (fromTOML (readFile path)).toolchain;
- inherit fromRustupToolchain;
+ inherit fromRustupToolchain fromRustupToolchainFile;
  };
 
  # All attributes below are for compatiblity with mozilla overlay.

tests/rust-toolchain-legacy

@@ -0,0 +1 @@
+nightly-2020-07-10