src/Console/ConfigurationResolver.php
private function resolveOptionBooleanValue($optionName)
    {
        $value = $this->options[$optionName];
        if (\is_bool($value)) {
            return $value;
        }

        if (!\is_string($value)) {
            throw new InvalidConfigurationException(sprintf('Expected boolean or string value for option "%s".', $optionName));
        }

        if ('yes' === $value) {
            return true;
        }

        if ('no' === $value) {
            return false;
        }

        $message = sprintf('Expected "yes" or "no" for option "%s", other values are deprecated and support will be removed in 3.0. Got "%s", this implicitly set the option to "false".', $optionName, $value);

        if (getenv('PHP_CS_FIXER_FUTURE_MODE')) {
            throw new InvalidConfigurationException("{$message} This check was performed as `PHP_CS_FIXER_FUTURE_MODE` env var is set.");
        }

        @trigger_error($message, E_USER_DEPRECATED);

        return false;
    }
private function resolveOptionBooleanValue($optionName)
    {
        $value = $this->options[$optionName];
        if (\is_bool($value)) {
            return $value;
        }

        if (!\is_string($value)) {
            throw new InvalidConfigurationException(sprintf('Expected boolean or string value for option "%s".', $optionName));
        }

        if ('yes' === $value) {
            return true;
        }

        if ('no' === $value) {
            return false;
        }

        $message = sprintf('Expected "yes" or "no" for option "%s", other values are deprecated and support will be removed in 3.0. Got "%s", this implicitly set the option to "false".', $optionName, $value);

        if (getenv('PHP_CS_FIXER_FUTURE_MODE')) {
            throw new InvalidConfigurationException("{$message} This check was performed as `PHP_CS_FIXER_FUTURE_MODE` env var is set.");
        }

        @trigger_error($message, E_USER_DEPRECATED);

        return false;
    }
@param string $optionName

@return bool