From b41229ca07af04e310b70fba24ec99f1cafc3913 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Thu, 15 May 2025 13:18:19 +0300
Subject: [PATCH] build(Cargo.toml): set minimum supported Rust version
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Sets the MSRV for the crate. The `rust-toolchain.toml` file is dropped since
this is too retrictive when choosing choosing a toolchain for developing the
crate – uses exact semantics.

It is necessary to change the `flake.nix` to read this version from the
`Cargo.toml` so that it can select the rust toolchain to use via `rust-overlay`.

Signed-off-by: Lars Wirzenius <liw@liw.fi>
Co-authored-by: Fintan Halpenny <fintan.halpenny@gmail.com>
---
 Cargo.toml          |  3 +++
 flake.lock          | 18 +++++++++---------
 flake.nix           |  6 +++++-
 rust-toolchain.toml |  4 ----
 4 files changed, 17 insertions(+), 14 deletions(-)
 delete mode 100644 rust-toolchain.toml

diff --git a/Cargo.toml b/Cargo.toml
index 1f35143..71059fc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,6 +5,9 @@ license = "MIT OR Apache-2.0"
 version = "0.1.0"
 authors = ["Fintan Halpenny <fintan.halpenny@gmail.com>"]
 edition = "2021"
+# N.B. always use the full semver so that rust-overlay in `flake.nix` can select
+# the correct version
+rust-version = "1.82.0"
 
 [dependencies]
 indexmap = { version = "2.7.1", features = ["serde"] }
diff --git a/flake.lock b/flake.lock
index 45f8812..eea34c9 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "crane": {
       "locked": {
-        "lastModified": 1742394900,
-        "narHash": "sha256-vVOAp9ahvnU+fQoKd4SEXB2JG2wbENkpqcwlkIXgUC0=",
+        "lastModified": 1747260204,
+        "narHash": "sha256-KUb6MFWc2DYeTCmcEkrBrrqhxAgO6NHZh5qQKwsjG6I=",
         "owner": "ipetkov",
         "repo": "crane",
-        "rev": "70947c1908108c0c551ddfd73d4f750ff2ea67cd",
+        "rev": "7f85510df37247c86a0c44032f49aa18292ee11f",
         "type": "github"
       },
       "original": {
@@ -35,11 +35,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1742998488,
-        "narHash": "sha256-r7dqSLNkzg1rOPsq4Tuc6p+UtAGqNRMma4riupsuZv4=",
+        "lastModified": 1747308931,
+        "narHash": "sha256-aFP8PqwBbokBQ6IKpD71RbhSWV4qjyg6M0y62rodRts=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8e0b1e9c8c4dfaef0ff85e09c91294ba4afa4168",
+        "rev": "ed8ec80540abb9a7e69da65916cf3d0b26174555",
         "type": "github"
       },
       "original": {
@@ -64,11 +64,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1742956365,
-        "narHash": "sha256-Slrqmt6kJ/M7Z/ce4ebQWsz2aeEodrX56CsupOEPoz0=",
+        "lastModified": 1747190175,
+        "narHash": "sha256-s33mQ2s5L/2nyllhRTywgECNZyCqyF4MJeM3vG/GaRo=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "a0e3395c63cdbc9c1ec17915f8328c077c79c4a1",
+        "rev": "58160be7abad81f6f8cb53120d5b88c16e01c06d",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 72c50bc..ba7578d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -29,7 +29,10 @@
         overlays = [(import rust-overlay)];
       };
 
-      rustToolChain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+      # Get the `rust-version` from the Cargo manifest
+      manifest = builtins.fromTOML (builtins.readFile ./Cargo.toml);
+      rust-version = manifest.package.rust-version;
+      rustToolChain = pkgs.rust-bin.stable.${rust-version}.default;
       craneLib = (crane.mkLib pkgs).overrideToolchain rustToolChain;
 
       src = lib.cleanSourceWith {
@@ -99,6 +102,7 @@
         # Extra inputs can be added here; cargo and rustc are provided by default
         # from the toolchain that was specified earlier.
         packages = with pkgs; [
+          cargo-nextest
           cargo-watch
           ripgrep
           rust-analyzer
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
deleted file mode 100644
index ba99c25..0000000
--- a/rust-toolchain.toml
+++ /dev/null
@@ -1,4 +0,0 @@
-[toolchain]
-channel = "1.84"
-profile = "default"
-components = [ "rust-src" ]