PHP 7 will be the stricter PHP version, with over 400 error messages. They range from reporting a fatal compilation error to helping with strict standards. During the session, we'll review old-timer messages that are still plaguing us, new ones that are not linked to new features, and even a few that are disappearing. Funny at times, more serious at others, this session will help understand the messages that PHP reports and how to take advantage of them for better coding.

1. PHP 7.0'S
ERROR MESSAGES
HAVING FUN WITH ERRORS
PHPAmersfoort

2. AGENDA
• 2229 error messages to review
• New gotchas
• New features, new messages

3. SPEAKER
• Damien Seguy
• CTO at exakat
• "Ik ben een boterham" : I'm a resident
• Automated code audit services

4. EVOLUTION OF ERROR MESSAGES

5. SEARCHING FOR MESSAGES
• PHP-src repository
• zend_error
• zend_throw
• zend_throw_exception
• zend_error_throw

6. 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)

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

8. EXCEPTIONS ARE ON THE RISE

9. AGENDA
• New error messages (New features)
• Better linting
• Removed messages
• Cryptic messages

10. NEW FEATURES

11. RETURN VALUE OF %S%S%S()
MUST %S%S, %S%S RETURNED
<?php
function x(): array {
return false;
}
?>
Uncaught TypeError: Return value of x() must be of the type array,
boolean returned in

12. 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

13. 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

14. DEFAULT VALUE FOR PARAMETERS WITH
A FLOAT TYPE HINT CAN ONLY BE FLOAT
<?php
function foo(float $a = "3"){
return true;
}
?>

15. DEFAULT VALUE FOR PARAMETERS WITH
A FLOAT TYPE HINT CAN ONLY BE FLOAT
<?php
function foo(float $a = 3 ){
return true;
}
?>

16. CANNOT USE TEMPORARY
EXPRESSION IN WRITE CONTEXT
<?php
'foo'[0] = 'b';
?>

17. CANNOT USE TEMPORARY
EXPRESSION IN WRITE CONTEXT
<?php
$a = 'foo';
$a[0] = 'b';
print $a;
?>

18. CANNOT USE "%S" WHEN NO
CLASS SCOPE IS ACTIVE
<?php
function x(): parent {
return new bar();
}
x();
?>
• self
• parent
• static

19. CANNOT USE "%S" WHEN NO
CLASS SCOPE IS ACTIVE
<?php
class bar extends baz {}
class foo extends bar {
function x(): parent {
return new foo();
}
}
$x = new foo(); $x->x();
?>

20. CANNOT USE "%S" WHEN NO
CLASS SCOPE IS ACTIVE
<?php
class bar extends baz {}
class foo extends bar {
function x(): parent {
return new bar();
}
}
$x = new foo(); $x->x();
?>

21. CANNOT USE "%S" WHEN NO
CLASS SCOPE IS ACTIVE
<?php
class baz {}
class bar extends baz {}
class foo extends bar {
function x(): parent {
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

22. CANNOT USE "%S" WHEN NO
CLASS SCOPE IS ACTIVE
<?php
class baz {}
class bar extends baz {}
class foo extends bar {
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

23. CANNOT DECLARE A RETURN
TYPE
• __construct
• __destruct
• __clone
• "PHP 4 constructor"
<?php
class x {
function __construct() : array {
return true;
}
function x() : array {
return true;
}
}
?>

24. 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;
}
}
?>

25. INVALID UTF-8 CODEPOINT
ESCAPE SEQUENCE
我爱你
<?php
$a = "u{6211}u{7231}u{4f60}";
echo $a;
?>

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

27. NEW LINTING

28. 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 rarely useful
<?php
class x {
const class = 1;
}
?>

29. 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 rarely useful
• 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)

30. DYNAMIC CLASS NAMES ARE NOT
ALLOWED IN COMPILE-TIME ::CLASS FETCH
<?php
$c = new class {
function f() {
echo $x::class;
}
};
$c->f();
?>

31. REDEFINITION OF PARAMETER
$%S
<?php
function foo($a, $a, $a) {
echo "$an";
}
foo(1,2,3);
?>

32. SWITCH STATEMENTS MAY ONLY
CONTAIN ONE DEFAULT CLAUSE
<?php
switch($x) {
case '1' :
break;
default :
break;
default :
break;
case '2' :
break;
}
?>

33. 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;

34. EXCEPTIONS MUST IMPLEMENT
THROWABLE
<?php
throw new stdClass();
?>
Fatal error: Uncaught Error: Cannot throw objects that do not
implement Throwable

35. 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

36. RETIRED MESSAGES

37. FATAL ERROR
<?php
interface t{}
trait t{}
?>
Fatal error: Cannot redeclare class t in

38. 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 REMOVE

39. 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

40. CRYPTIC MESSAGES

41. 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));
?>

42. DIVISION OF PHP_INT_MIN BY
-1 IS NOT AN INTEGER
• PHP_INT_MIN is the smallest integer on PHP
• PHP_INT_MAX : 9223372036854775807
• PHP_INT_MIN : -9223372036854775808
• Division or multiplication leads to non-integer
• Uses the Integer Division intdiv()

43. WEBP DECODE: REALLOC
FAILED
• New image format for the Web
• Lossless compression, small files
• gdImageCreateFromWebpCtx emit this
• Probably very bad

44. FUNCTION NAME MUST BE A
STRING
<?php
if ($_GET('X') == 'Go') {
ProcessFile();
return;
}
?>

45. ENCODING DECLARATION
PRAGMA MUST BE THE VERY
FIRST STATEMENT IN THE SCRIPT

46. NAMESPACE DECLARATION
STATEMENT HAS TO BE THE VERY
FIRST STATEMENT IN THE SCRIPT

47. NAMESPACE DECLARATION
STATEMENT HAS TO BE THE VERY
FIRST STATEMENT IN THE SCRIPT
ENCODING DECLARATION
PRAGMA MUST BE THE VERY
FIRST STATEMENT IN THE SCRIPT

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

49. YOU SEEM TO BE TRYING TO
USE A DIFFERENT LANGUAGE...
<?php
use strict;

50. WHAT ABOUT MY CODE?

51. 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?

52. • die('I SEE ' . $action . ' - ' . $_POST['categories_id']);
• die("Error: application_top not found.nMake sure you have placed the
currency_cron.php 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);

53. DANK U WEL
@EXAKAT