rustPlatform.importCargoLock: add support for v1 lock files

pkgs/build-support/rust/import-cargo-lock.nix

@@ -36,7 +36,9 @@ let
     then builtins.readFile lockFile
     else args.lockFileContents;
 
-  packages = (builtins.fromTOML lockFileContents).package;
+  parsedLockFile = builtins.fromTOML lockFileContents;
+
+  packages = parsedLockFile.package;
 
   # There is no source attribute for the source package itself. But
   # since we do not want to vendor the source package anyway, we can
@@ -79,17 +81,16 @@ let
   # We can't use the existing fetchCrate function, since it uses a
   # recursive hash of the unpacked crate.
   fetchCrate = pkg:
-    assert lib.assertMsg (pkg ? checksum) ''
+    let
+      checksum = pkg.checksum or parsedLockFile.metadata."checksum ${pkg.name} ${pkg.version} (${pkg.source})";
+    in
+    assert lib.assertMsg (checksum != null) ''
       Package ${pkg.name} does not have a checksum.
-      Please note that the Cargo.lock format where checksums used to be listed
-      under [metadata] is not supported.
-      If that is the case, running `cargo update` with a recent toolchain will
-      automatically update the format along with the crate's depenendencies.
     '';
     fetchurl {
       name = "crate-${pkg.name}-${pkg.version}.tar.gz";
       url = "https://crates.io/api/v1/crates/${pkg.name}/${pkg.version}/download";
-      sha256 = pkg.checksum;
+      sha256 = checksum;
     };
 
   # Fetch and unpack a crate.
@@ -105,7 +106,7 @@ let
         tar xf "${crateTarball}" -C $out --strip-components=1
 
         # Cargo is happy with largely empty metadata.
-        printf '{"files":{},"package":"${pkg.checksum}"}' > "$out/.cargo-checksum.json"
+        printf '{"files":{},"package":"${crateTarball.outputHash}"}' > "$out/.cargo-checksum.json"
       ''
       else if gitParts != null then
       let

pkgs/build-support/rust/test/import-cargo-lock/default.nix

@@ -11,4 +11,5 @@
   gitDependencyTag = callPackage ./git-dependency-tag { };
   gitDependencyBranch = callPackage ./git-dependency-branch { };
   maturin = callPackage ./maturin { };
+  v1 = callPackage ./v1 { };
 }

pkgs/build-support/rust/test/import-cargo-lock/v1/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "v1"
+version = "0.1.0"
+authors = ["Daniël de Kok <[email protected]>"]
+edition = "2018"
+
+[dependencies]
+rand = "0.8"

pkgs/build-support/rust/test/import-cargo-lock/v1/default.nix

@@ -0,0 +1,18 @@
+{ rustPlatform }:
+
+rustPlatform.buildRustPackage {
+  pname = "v1";
+  version = "0.1.0";
+
+  src = ./.;
+
+  cargoLock = {
+    lockFile = ./Cargo.lock;
+  };
+
+  doInstallCheck = true;
+
+  installCheckPhase = ''
+    $out/bin/v1
+  '';
+}

pkgs/build-support/rust/test/import-cargo-lock/v1/src/main.rs

@@ -0,0 +1,9 @@
+use rand::Rng;
+
+fn main() {
+    let mut rng = rand::thread_rng();
+
+    // Always draw zero :).
+    let roll: u8 = rng.gen_range(0..1);
+    assert_eq!(roll, 0);
+}