From fa7f4e68c5183cba9a41f497907aae381c73b563 Mon Sep 17 00:00:00 2001
From: Philip Metzger <philipmetzger@bluewin.ch>
Date: Wed, 24 Jul 2024 20:16:03 +0200
Subject: [PATCH] run: Treat `jj run -j0 <command>` as use all available cores

Waleed noticed this in #4021.
---
 cli/src/commands/run.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/cli/src/commands/run.rs b/cli/src/commands/run.rs
index cbcab0296..5a72251e7 100644
--- a/cli/src/commands/run.rs
+++ b/cli/src/commands/run.rs
@@ -59,9 +59,8 @@ pub fn cmd_run(ui: &mut Ui, command: &CommandHelper, args: &RunArgs) -> Result<(
     // 2. the amount of cores available.
     // 3. a single job, if all of the above fails.
     let _jobs = match args.jobs {
-        Some(0) => return Err(user_error("must pass at least one job")),
+        Some(0) | None => std::thread::available_parallelism().map(|t| t.into()).ok(),
         Some(jobs) => Some(jobs),
-        None => std::thread::available_parallelism().map(|t| t.into()).ok(),
     }
     // Fallback to a single user-visible job.
     .unwrap_or(1usize);