[llvm] [workflows] Add top-level permissions for libcxx-build-and-test.yaml (PR #73689)

[Tom Stellard via llvm-commits]

https://github.com/tstellar created https://github.com/llvm/llvm-project/pull/73689

This is the standard convention for our workflow files.

>From bcd87335aadff893e346377ada5b6cf8f7d22857 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Tue, 28 Nov 2023 10:40:52 -0800
Subject: [PATCH] [workflows] Add top-level permissions for
 libcxx-build-and-test.yaml

This is the standard convention for our workflow files.
---
 .github/workflows/libcxx-build-and-test.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index dccfe54d4646767..e929c02d11c1d93 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -23,6 +23,9 @@ on:
       - 'cmake/**'
       - '.github/workflows/libcxx-build-and-test.yaml'
 
+permissions:
+  contents: read # Default everything to read-only
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
   cancel-in-progress: true