From 96e4fada7a885f971d542d9cc5eb2bcf3a80766c Mon Sep 17 00:00:00 2001
From: leynos <leynos@rohga>
Date: Tue, 7 Jul 2026 12:22:09 +0200
Subject: [PATCH] Add a setup-commands input to the cargo mutation workflow

Callers cannot inject steps into a `workflow_call` job, so repositories
whose builds need job-level preparation had no way to satisfy it before
cargo-mutants runs. The concrete case is agent-template-rust review
feedback: generated repos render `.cargo/config.toml` with
`-fuse-ld=mold` on the default Linux target and their CI installs mold
before any cargo command; the mutation baseline would fail to link on a
bare runner.

`setup-commands` (default empty, preserving existing behaviour) runs
caller-supplied shell in each mutants job after toolchain setup and
before cargo-mutants, via a temp script under `set -euo pipefail`. The
input executes with the same privileges the caller's own workflows
already hold in their repository.
---
 .github/workflows/mutation-cargo.yml | 19 +++++++++++++++++++
 docs/mutation-cargo-workflow.md      |  1 +
 2 files changed, 20 insertions(+)

diff --git a/.github/workflows/mutation-cargo.yml b/.github/workflows/mutation-cargo.yml
index 49151204..fa417c7e 100644
--- a/.github/workflows/mutation-cargo.yml
+++ b/.github/workflows/mutation-cargo.yml
@@ -58,6 +58,14 @@ on:
           "--all-features" so feature-gated tests run against mutants.
         type: string
         default: ""
+      setup-commands:
+        description: >-
+          Shell commands run in each mutants job before cargo-mutants
+          (e.g. installing a linker such as mold, or system packages
+          the build needs). Executed with bash under `set -euo
+          pipefail`; empty means no extra setup.
+        type: string
+        default: ""
 
 # Default the token to no scopes; jobs opt in explicitly.
 permissions: {}
@@ -185,6 +193,17 @@ jobs:
             cargo binstall --no-confirm cargo-mutants
           fi
 
+      - name: Run setup commands
+        if: ${{ inputs.setup-commands != '' }}
+        shell: bash
+        env:
+          SETUP_COMMANDS: ${{ inputs.setup-commands }}
+        run: |
+          set -euo pipefail
+          script="${RUNNER_TEMP}/mutation-setup-commands.sh"
+          printf '%s\n' "${SETUP_COMMANDS}" > "${script}"
+          bash -euo pipefail "${script}"
+
       - name: Install uv (act)
         if: ${{ env.ACT == 'true' }}
         shell: bash
diff --git a/docs/mutation-cargo-workflow.md b/docs/mutation-cargo-workflow.md
index 55d361e2..56473dcb 100644
--- a/docs/mutation-cargo-workflow.md
+++ b/docs/mutation-cargo-workflow.md
@@ -83,6 +83,7 @@ jobs:
 | `shard-count` | `6` | Fan-out for full dispatch runs (scoped runs stay single-shard). |
 | `cargo-mutants-version` | pinned | Tool version; the summary parser is validated against it. |
 | `extra-args` | (empty) | Extra cargo-mutants arguments (shell-lexed), e.g. `--all-features`. |
+| `setup-commands` | (empty) | Shell commands run before cargo-mutants in each mutants job (e.g. `sudo apt-get install -y mold` when the repo's `.cargo/config.toml` selects that linker). |
 
 ## Notes