no-tab.yml

name: No-tabulation check

on: pull_request

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v7
      with:
        fetch-depth: 0

    - name: No-tabulation check
      run: |
        git fetch origin ${{ github.base_ref }}:${{ github.base_ref }}
        git diff ${{ github.base_ref }} -- . ':(exclude)*Makefile' ':(exclude)*.mk' | awk '
          /^\+\+\+ / { f=$2; sub(/^b\//,"",f); next }
          /^@@ /     { match($0,/\+[0-9]+/); ln=substr($0,RSTART+1,RLENGTH-1)+0; next }
          /^\+/      { if(index($0,"\t")){ printf "::error file=%s,line=%d::Tab character not allowed\n", f, ln; rc=1 } ln++; next }
          /^[ ]/     { ln++ }
          END        { exit rc }
        '