chore(rust): bump MSRV to 1.71.0

Summary: Let's be more aggressive about tracking the latest stable Rust release.
There's little benefit to being conservative so early on, especially when no
users seem to have faced any issue with upgrading, or strictly required an old
Rust version.

Right now, just lagging Rust by 1 major release probably seems fine. We're
targeting 1.71.0 to get ahead of the curve, since 1.72.0 will likely release
sometime before the next `jj` release.

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Change-Id: I4e691b6ba63b5b9023a75ae0a6917672

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
         cargo_flags: [""]
         include:
         - os: ubuntu-latest
-          rust_version: "1.64"
+          rust_version: "1.71"
           cargo_flags: ""
         - os: ubuntu-latest
           rust_version: stable
@@ -65,7 +65,7 @@ jobs:
         with:
           toolchain: nightly
           components: rustfmt
-      - run: cargo fmt --all -- --check
+      - run: cargo +nightly fmt --all -- --check
 
   cargo-deny:
     runs-on: ubuntu-latest
@@ -95,4 +95,4 @@ jobs:
         with:
           toolchain: stable
           components: clippy
-      - run: cargo clippy --all-features --workspace --all-targets -- -D warnings
+      - run: cargo +stable clippy --all-features --workspace --all-targets -- -D warnings

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking changes
 
+* The minimum supported Rust version (MSRV) is now 1.71.0.
+
 ### New features
 
 ### Fixed bugs

Cargo.toml

@@ -3,7 +3,7 @@ name = "jj-cli"
 version = "0.8.0"
 authors = ["Martin von Zweigbergk <martinvonz@google.com>"]
 edition = "2021"
-rust-version = "1.64"  # Remember to update CI, contributing.md, and flake.nix
+rust-version = "1.71"  # Remember to update CI, and contributing.md
 license = "Apache-2.0"
 description = "Jujutsu (an experimental VCS)"
 homepage = "https://github.com/martinvonz/jj"

docs/contributing.md

@@ -77,10 +77,12 @@ recommended steps.
 
 ### Summary
 
+If you already have `rustup` installed, then moving into the source code
+directory will install the MSRV for you.
+
 One-time setup:
 
-    rustup toolchain add nightly  # If this is not your default
-    rustup toolchain add 1.64     # See note about MSRV & `rust-version` below
+    rustup toolchain add nightly  # wanted for 'rustfmt'
     cargo install cargo-insta
     cargo install cargo-watch
     cargo install cargo-nextest
@@ -89,7 +91,7 @@ During development (adapt according to your preference):
 
     cargo watch --ignore '.jj/**' -s \
       'cargo clippy --workspace --all-targets \
-       && cargo +1.64 check --workspace --all-targets'
+       && cargo check --workspace --all-targets'
     cargo +nightly fmt # Occasionally
     cargo nextest run --workspace # Occasionally
     cargo insta test --workspace # Occasionally
@@ -116,9 +118,8 @@ These are listed roughly in order of decreasing importance.
    toolchain and use `cargo +nightly fmt`.
 
 3. Your code will be rejected if it cannot be compiled with the minimal
-   supported version of Rust ("MSRV"). This version is listed as
-   `rust-version` in [`Cargo.toml`](../Cargo.toml); it is 1.64 as of this
-   writing.
+   supported version of Rust ("MSRV"). Currently, `jj` follows a rather
+   casual MSRV policy: "The current `rustc` stable version, minus one."
 
 4. Your code needs to pass `cargo clippy`. You can also
    use `cargo +nightly clippy` if you wish to see more warnings.

flake.nix

@@ -35,6 +35,13 @@
             pkgs.lib.all (re: builtins.match re relPath == null) regexes;
         };
 
+      rust-version = pkgs.rust-bin.stable."1.71.0".default;
+
+      ourRustPlatform = pkgs.makeRustPlatform {
+        rustc = rust-version;
+        cargo = rust-version;
+      };
+
       # NOTE (aseipp): on Linux, go ahead and use mold by default to improve
       # link times a bit; mostly useful for debug build speed, but will help
       # over time if we ever get more dependencies, too
@@ -42,7 +49,7 @@
     in
     {
       packages = {
-        jujutsu = pkgs.rustPlatform.buildRustPackage rec {
+        jujutsu = ourRustPlatform.buildRustPackage rec {
           pname = "jujutsu";
           version = "unstable-${self.shortRev or "dirty"}";
           buildNoDefaultFeatures = true;
@@ -64,8 +71,9 @@
             makeWrapper
             pkg-config
           ];
-          buildInputs = with pkgs; [ openssl zstd libgit2 libssh2 ]
-            ++ lib.optionals stdenv.isDarwin [
+          buildInputs = with pkgs; [
+            openssl zstd libgit2 libssh2
+          ] ++ lib.optionals stdenv.isDarwin [
             darwin.apple_sdk.frameworks.Security
             darwin.apple_sdk.frameworks.SystemConfiguration
             libiconv
@@ -102,7 +110,7 @@
         buildInputs = with pkgs; [
           # Using the minimal profile with explicit "clippy" extension to avoid
           # two versions of rustfmt
-          (rust-bin.stable."1.64.0".minimal.override {
+          (rust-version.override {
             extensions = [
               "rust-src" # for rust-analyzer
               "clippy"

lib/Cargo.toml

@@ -3,7 +3,7 @@ name = "jj-lib"
 version = "0.8.0"
 authors = ["Martin von Zweigbergk <martinvonz@google.com>"]
 edition = "2021"
-rust-version = "1.64"
+rust-version = "1.71"
 license = "Apache-2.0"
 description = "Library for Jujutsu (an experimental VCS)"
 homepage = "https://github.com/martinvonz/jj"