#!/bin/bash

# fail if we add any new lines to C or Scheme source containing a tab
if git diff --name-only | egrep '\.(cpp|h|scm|sld|stub)$' | xargs -d'\n' git diff -U0 -- | grep -q $'^+ *\t'; then
    echo "Error: Attempting to add a source file using tabs for indentation."
    echo
    echo -n "   "
    git diff --name-only |\
        egrep '\.(cpp|h|scm|sld|stub)$' |\
        xargs -d'\n' git diff -U0 -- |\
        grep $'^+ *\t' | head -1
    echo
    cat <<EOF
It's important for arguments to line up vertically to a precise column.
Since there is no standard tab width, using tabs for indentation makes
this impossible in general.  Please use spaces.
EOF
    exit 1
fi