rustPlatform.importCargoLock: add support for v1 lock files

v1 lock files (generated by default by Cargo versions 1.40 and below)
use a single table, `metadata`, to store the checksums of packages.

The primary motivation for doing this now is that we're considering
vendoring all Cargo lock files in Nixpkgs, some packages still use it
(e.g. cargo-asm), and adding support for it doesn't increase the
complexity of the function. No matter the outcome of the vendoring
discussion, this is a nice thing to have because Cargo still supports 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.lock

@@ -0,0 +1,85 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "getrandom"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.94 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasi 0.10.2+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.94"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "rand"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.94 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_chacha 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_hc 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "ppv-lite86 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "getrandom 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_hc"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand_core 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "v1"
+version = "0.1.0"
+dependencies = [
+ "rand 0.8.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "wasi"
+version = "0.10.2+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[metadata]
+"checksum cfg-if 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+"checksum getrandom 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c9495705279e7140bf035dde1f6e750c162df8b625267cd52cc44e0b156732c8"
+"checksum libc 0.2.94 (registry+https://github.com/rust-lang/crates.io-index)" = "18794a8ad5b29321f790b55d93dfba91e125cb1a9edbd4f8e3150acc771c1a5e"
+"checksum ppv-lite86 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "ac74c624d6b2d21f425f752262f42188365d7b8ff1aff74c82e45136510a4857"
+"checksum rand 0.8.3 (registry+https://github.com/rust-lang/crates.io-index)" = "0ef9e7e66b4468674bfcb0c81af8b7fa0bb154fa9f28eb840da5c447baeb8d7e"
+"checksum rand_chacha 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e12735cf05c9e10bf21534da50a147b924d555dc7a547c42e6bb2d5b6017ae0d"
+"checksum rand_core 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "34cf66eb183df1c5876e2dcf6b13d57340741e8dc255b48e40a26de954d06ae7"
+"checksum rand_hc 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3190ef7066a446f2e7f42e239d161e905420ccab01eb967c9eb27d21b2322a73"
+"checksum wasi 0.10.2+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)" = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"

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 <me@danieldk.eu>"]
+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);
+}