src/PEAR/Dependency2.php
function validateArchDependency($dep)
    {
        if ($this->_state != PEAR_VALIDATE_INSTALLING) {
            return true;
        }

        $not = isset($dep['conflicts']) ? true : false;
        if (!$this->matchSignature($dep['pattern'])) {
            if (!$not) {
                if (!isset($this->_options['nodeps']) && !isset($this->_options['force'])) {
                    return $this->raiseError('%s Architecture dependency failed, does not ' .
                        'match "' . $dep['pattern'] . '"');
                }

                return $this->warning('warning: %s Architecture dependency failed, does ' .
                    'not match "' . $dep['pattern'] . '"');
            }

            return true;
        }

        if ($not) {
            if (!isset($this->_options['nodeps']) && !isset($this->_options['force'])) {
                return $this->raiseError('%s Architecture dependency failed, required "' .
                    $dep['pattern'] . '"');
            }

            return $this->warning('warning: %s Architecture dependency failed, ' .
                'required "' . $dep['pattern'] . '"');
        }

        return true;
    }
function validateArchDependency($dep)
    {
        if ($this->_state != PEAR_VALIDATE_INSTALLING) {
            return true;
        }

        $not = isset($dep['conflicts']) ? true : false;
        if (!$this->matchSignature($dep['pattern'])) {
            if (!$not) {
                if (!isset($this->_options['nodeps']) && !isset($this->_options['force'])) {
                    return $this->raiseError('%s Architecture dependency failed, does not ' .
                        'match "' . $dep['pattern'] . '"');
                }

                return $this->warning('warning: %s Architecture dependency failed, does ' .
                    'not match "' . $dep['pattern'] . '"');
            }

            return true;
        }

        if ($not) {
            if (!isset($this->_options['nodeps']) && !isset($this->_options['force'])) {
                return $this->raiseError('%s Architecture dependency failed, required "' .
                    $dep['pattern'] . '"');
            }

            return $this->warning('warning: %s Architecture dependency failed, ' .
                'required "' . $dep['pattern'] . '"');
        }

        return true;
    }
Specify a complex dependency on an OS/processor/kernel version,
Use OS for simple operating system dependency.

This is the only dependency that accepts an eregable pattern.  The pattern
will be matched against the php_uname() output parsed by OS_Guess