From 54b39be7e793e21b0347f2a8141909cbc37abfb8 Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Wed, 22 Oct 2025 18:47:15 +0200
Subject: [PATCH] build_tools/style.fish: check that {rustfmt,Cargo}.toml
 edition specs are in sync

Commit 1fe6b288779 (rustfmt.toml: specify edition to allow 2024 syntax,
2025-10-19) mentions that "cargo fmt" has different behavior than
"rustfmt" before that commit.  Probably because when .rustfmt.toml
exists, rustfmt implicitly uses a different edition (2018?)  that
doesn't support c"" yet.  That commit bumped the edition to 2024,
which caused yet another deviation from "cargo fmt":

    Error writing files: failed to resolve mod `tests`: cannot parse /home/johannes/git/fish-shell/src/wutil/tests.rs
    error: expected identifier, found reserved keyword `gen`
      --> /home/johannes/git/fish-shell/src/tests/topic_monitor.rs:48:9
       |
    48 |     for gen in &mut gens_list {
       |         ^^^ expected identifier, found reserved keyword

This has since been fixed by
00784248db8 (Update to rust 2024 edition, 2025-10-22).

Let's add a test so that such changes won't randomly break "rustfmt"
again.

Fix that by using 2021 edition, like we do in Cargo.toml.

In future, rustfmt should probably default to a current edition (or
maybe read the edition from Cargo.toml?)  Not yet sure which one is the
upstream issue, maybe https://github.com/rust-lang/rustfmt/issues/5650
---
 .github/workflows/lint.yml | 3 +++
 .rustfmt.toml              | 1 -
 build_tools/style.fish     | 4 ++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 8f424e08c..0dd9d5c09 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -19,6 +19,9 @@ jobs:
       run: cargo build
     - name: check format
       run: PATH="target/debug:$PATH" build_tools/style.fish --all --check
+    - name: check rustfmt
+      run: find build.rs crates src -type f -name '*.rs' | xargs rustfmt --check
+
 
   clippy:
     runs-on: ubuntu-latest
diff --git a/.rustfmt.toml b/.rustfmt.toml
index f3e454b61..f216078d9 100644
--- a/.rustfmt.toml
+++ b/.rustfmt.toml
@@ -1,2 +1 @@
 edition = "2024"
-style_edition = "2024"
diff --git a/build_tools/style.fish b/build_tools/style.fish
index 0cc612bf5..f26305f20 100755
--- a/build_tools/style.fish
+++ b/build_tools/style.fish
@@ -101,6 +101,10 @@ if test $all = yes; or set -q rust_files[1]
         exit 127
     end
 
+    set -l edition_spec string match -r '^edition\s*=.*'
+    test "$($edition_spec <Cargo.toml)" = "$($edition_spec <.rustfmt.toml)"
+    or die "Cargo.toml and .rustfmt.toml use different editions"
+
     echo === Running "$green"rustfmt"$normal"
     if set -l -q _flag_check
         if test $all = yes