#! /bin/bash

declare -a IGNORED_CONFIGS_RE=(
	"CONFIG_GCC_VERSION"
	"CONFIG_LD_VERSION"
	"CONFIG_CC_VERSION_TEXT"
	"CONFIG_CC_HAS_"
	"CONFIG_CC_HAVE_"
	"CONFIG_CC_CAN_"
	"CONFIG_HAVE_[A-Z]*_COMPILER"
	"CONFIG_TOOLS_SUPPORT_"
)

declare -a SED_ARGS=()

for CONFIG in "${IGNORED_CONFIGS_RE[@]}"; do
	SED_ARGS+=(-e "/$CONFIG/ d")
done

SED_ARGS+=(
	-e '/^# .* is not set$/p'
	-e '/^$\|^#/d'
)

# lines 4 contains a timestamp...
differences="$(
    diff -bU0 <(sed "${SED_ARGS[@]}" "$1" | sort) \
	      <(sed "${SED_ARGS[@]}" "$2" | sort) \
    | grep '^[-+][^-+]'
)" || true
if [ -n "$differences" ]; then
    echo
    echo "Changes after running \`make oldconfig':"
    echo "$differences"
    echo
    if echo "$differences" | grep -q '^+' ; then
	exit 1
    fi
fi