errors in php 7

PHP 7.0's
error messages
Having fun with errors
Washington DC, USA, 2015

Agenda
• 2200 error messages to review
• New features, new traps, new messages

Speaker
• Damien Seguy
• CTO at exakat
• PHP static auditing engine

Searching for messages
• PHP-src repository
• zend_error
• zend_throw
• zend_throw_exception
• zend_error_throw

TOP 5 (from the source)
1. Using $this when not in object context (192)
2. Cannot use string offset as an array (74)
3. Cannot use string offset as an object (56)
4. Only variable references should be yielded by
reference (52)
5. Undeﬁned variable: %s (43)

TOP 5 (Google)
1. Call to undefined function
2. Class not found
3. Allowed memory size of
4. Undefined index
5. Undefined variable

Exceptions are on the rise
%
%
%
%

Agenda
• New error messages
• Better linting
• Removed messages
• Cryptic messages

Return value of %s%s%s()
must %s%s, %s%s returned
<?php
  function x(): myClass {
   return false;
}

?>
Uncaught TypeError: Return value of x() must be of the type myClass,
boolean returned in…

Return value of %s%s%s()
must %s%s, %s%s returned
<?php
  function x(): array {
   return ;
  }

?>
Uncaught TypeError: Return value of x() must be of the type array,
none returned in…

Argument %d passed to %s%s%s() must %s
%s, %s%s given, called in %s on line %d
<?php
function x(array $a)  {
  return false;
}
x(false);

?>
Uncaught TypeError: Argument 1 passed to x() must be of the type
array, boolean given, called in

Default value for parameters with
a float type hint can only be float
<?php
    function foo(float $a = "3"){
        return true;
    }
?>

Default value for parameters with
a float type hint can only be float
<?php
    function foo(float $a = 3 ){
        return true;
    }
?>

Cannot use temporary
expression in write context
<?php
$a = 'foo'[0];
'foo'[0] = 'b';
?>
Parse error: syntax error, unexpected '=' in

Cannot use temporary
expression in write context
<?php
$a = 'foo';
$a[0] = 'b';
print $a;
?>

Cannot use "%s" when no
class scope is active
<?php
  function x(): parent {
    return new bar();
}
x();
?>
• self • parent • static

<?php
class bar extends baz {}
class foo extends bar {
    return new foo();
}
}
$x = new foo();  $x->x();
?>

<?php
    return new bar();
}
}
$x = new foo();  $x->x();
?>

<?php
class baz {}
    return new baz();
}
}
$x = new foo(); $x->x();
?>Uncaught TypeError: Return value of foo::x() must be an instance of
bar, instance of baz returned in

Different parents
class great-great-grandparent
class great-grandparent
class parent
class self
class child
class grand-child
class great-grandchild
class great-great-grandchild
<?php
class self {
  function x() {
    parent::y();
}
}
<?php
class self {
  function x() : parent {
    return $something;
}
}

class scope is active<?php
class baz {}
  function x(): grandparent {
    return new baz();
}
}
$x = new foo(); $x->x();
?>
Uncaught TypeError: Return value of foo::x() must be an instance of
grandparent, instance of bar returned

Useful in traits
Fatal error: Cannot access parent:: when current
class scope has no parent
<?php
trait t {
  function x() : parent {
    return $something;
}
}
class c {
  use t;
}

cannot declare a return type
• __construct
• __destruct
• __clone
• "PHP 4 constructor"
<?php
class x {
    function __construct() : array {
        return true;
    }
    function x() : array {
        return true;
    }
}
?>

Methods with the same name as their
class will not be constructors in a
future version of PHP; %s has a
deprecated constructor
<?php
class x {
    function x() : array {
        return true;
    }
}
?> M
ost
frequent
error
(95%
)

Invalid UTF-8 codepoint
escape sequence
我爱你
<?php
$a = "u{6211}u{7231}u{4f60}";
echo $a;
?>

Invalid UTF-8 codepoint
escape sequence
• Incompatible with PHP 5.6
• Good for literals
• Alternatives?
<?php
$a = "u{de";
echo $a;
?>
<?php
echo json_decode('"u'.$unicode.'"');
echo mb_convert_encoding('&#x'.$unicode.';', 'UTF-8', 'HTML-ENTITIES');
echo html_entity_decode('&#'.hexdec($unicode).';', 0, 'UTF-8');
     eval('"u{'.$unicode.'}n"');
?>

A class constant must not be called 'class';
it is reserved for class name fetching
• Used to be a parse error. Now a nice message.
• Still a bad idea
<?php
class x {
    const class = 1;
    const const = 2;
}
?>

A class constant must not be called 'class';
it is reserved for class name fetching
• Outside class will  
generate 
the old error
<?php
//class x {
    const class = 1;
//}
?>
Parse error: syntax error, unexpected 'class' (T_CLASS), expecting
identiﬁer (T_STRING)

Dynamic class names are not
allowed in compile-time ::class fetch
<?php
$c = new class {
function f() {
echo $x::class;
}
};
$c->f();
?>

Redefinition of parameter $%s
<?php
function foo($a, $a, $a) {
  echo "$an";
}
foo(1,2,3);
?>

Switch statements may only
contain one default clause
<?php
switch($x) {
    case '1' :
        break;
    default :
        break;
    default :
        break;
    case '2' :
        break;
}
?>

Switch statements may only
contain one default clause
<?php
switch($x) {
    case 1 :
        break;
    case 0+1 :
        break;
    case '1' :
        break;
    case true :
        break;
    case 1.0 :
        break;
    case $y :
        break;

Exceptions must
implement Throwable
<?php
throw new stdClass();
?>
Fatal error: Uncaught Error: Cannot throw objects that do not
implement Throwable

Exceptions must
implement Throwable
<?php
class e implements Throwable {
/* Methods */
public function  getMessage() {}
public function  getCode() {}
public function  getFile() {}
public function  getLine() {}
public function  getTrace() {}
public function  getTraceAsString() {}
public function  getPrevious() {}
public function  __toString() {}
}
?>
Class e cannot implement interface Throwable, extend Exception or
Error instead

Gone for good
It is not safe to rely on the system's timezone
settings. You are *required* to use the date.timezone
setting or the date_default_timezone_set() function. In
case you used any of those methods and you are still
getting this warning, you most likely misspelled the
timezone identiﬁer.

Catchable fatal error
<?php
function x(string $s) {
echo "$sn";
}
x('php');
?>
Catchable fatal error: Argument 1 passed to x() must be an instance of
string, string given

New scalar typehint
• string, real, bool, ﬂoat, int
• resource, mixed, numeric, object
• Can't be used for a class name anymore

Catchable fatal error
<?php
function x(resource $s) {
echo "$sn";
}
x(fopen('a.php','w+'));
?>
Catchable fatal error: Argument 1 passed to x() must be an instance of
resource, resource given

Fatal Error
<?php
interface t{}
trait t{}
?>
Fatal error: Cannot redeclare class t in

Call-time pass-by-reference
has been removed;
<?php
$a = 3;
function f($b) {
    $b++;
}
f(&$a);
print $a;
?>
Fatal error: Call-time pass-by-reference has been removed; If you would
like to pass argument by reference, modify the declaration of f(). in
has been removed

Call-time pass-by-reference
has been removed;
<?php
$a = 3;
function f($b) {
    $b++;
}
f(&$a);
print $a;
?>
PHP Parse error: syntax error, unexpected '&' in

Minimum value must be less than
or equal to the maximum value
<?php
var_dump(random_int(100, 999));
var_dump(random_int(-1000, 0));
var_dump(random_bytes(10));
?>
PHP Parse error: Could not gather sufﬁcient random data

Division of PHP_INT_MIN
by -1 is not an integer
• PHP_INT_MAX : 9223372036854775807
• PHP_INT_MIN is the smallest integer on PHP
• PHP_INT_MIN : -9223372036854775808
• Division or multiplication leads to non-integer
• Uses the Integer Division intdiv()

WebP decode: realloc failed
• New image format for the Web
• Lossless compression, small ﬁles
• gdImageCreateFromWebpCtx emit this
• Probably very bad

Function name must be
a string
<?php
if ($_GET('X') == 'Go') {
    ProcessFile();
    return;
}
?>

Encoding declaration pragma
must be
the very first statement
in the script

Namespace declaration
statement
has to be
in the script

Namespace declaration
statement
has to be
in the script
Encoding declaration pragma
must be
in the script

<?php
namespace myNamespace;
declare(encoding='ISO-8859-1');
// code here
// --enable-zend-multibyte
?>
First STATEMENT EVER
<?php
declare(encoding='ISO-8859-1');
namespace myNamespace;

// code here
// --enable-zend-multibyte
?>

First STATEMENT EVER
<?php
declare(encoding='UTF8');
namespace ⼈人 {
echo __NAMESPACE__;
}
?>

You seem to be trying to
use a different language...
<?php
use strict;

Fun with errors
• Check the errors messages in your application
• die, exit
• echo, print, display, debug, wp_die 
(depends on conventions)
• new *Exception()
• What does your application tells you?

• die('I SEE ' . $action . ' - ' . $_POST['categories_id']);
• die("Error: application_top not found.nMake sure you have placed the currency_cron.ph
file in your (renamed) Admin folder.nn");
• die('ERROR: admin/includes/configure.php file not found. Suggest running zc_install/
index.php?');
• die('I WOULD NOT ADD ' . $new_categories_sort_array[$i] . '<br>');
• die('NOTCONFIGURED');
• die('halted');
• die('<pre>' . print_r($inputs, true));
• die('HERE_BE_MONSTERS - could not open file');}
• die('HERE_BE_MONSTERS');}
• die($prod_id);
• die('here');
• die('Sorry. File not found. Please contact the webmaster to report this error.<br />c/
f: ' . $origin_filename);

errors in php 7

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