Implement 'Saner Numeric Strings' RFC:

RFC: https://wiki.php.net/rfc/saner-numeric-strings

This removes the -1 allow_error mode from is_numeric_string functions and replaces it by
a trailing boolean out argument to preserve BC in a couple of places.

Most of the changes can be resumed to "numeric" strings which emitted a E_NOTICE now emit
a E_WARNING and "numeric" strings which emitted a E_WARNING now throw a TypeError.

This mostly affects:
 - String offsets
 - Arithmetic operations
 - Bitwise operations

Closes GH-5762

Author: Girgias

UPGRADING

@@ -217,6 +217,27 @@ PHP 8.0 UPGRADE NOTES
   . debug_backtrace() and Exception::getTrace() will no longer provide
     references to arguments. It will not be possible to change function
     arguments through the backtrace.
+  . The concept of numeric-string has been altered to be less error prone.
+    Trailing whitespaces are now allowed in numeric strings making it symmetric
+    with how leading whitespaces were treated.
+    This mostly affects:
+     - The is_numeric() function
+     - String-to-string comparisons
+     - Type declarations
+     - Increment and Decrement operations
+    The concept of "leading-numeric string" has been mostly dropped, the cases
+    where this concept remains is in order to ease migration.
+    String which emitted an E_NOTICE "A non well formed numeric value encountered"
+    will now emit an E_WARNING "A non-numeric value encountered"
+    and all strings which emitted an E_WARNING "A non-numeric value encountered"
+    will now throw a TypeError.
+    This mostly affects:
+     - Arithmetic operations
+     - Bitwise operations
+    This E_WARNING to TypeError change also affects the E_WARNING
+    "Illegal string offset 'string'" for illegal string offsets.
+    This does not change the behaviour of explicit casts to int/float from strings.
+    RFC: https://wiki.php.net/rfc/saner-numeric-strings
 
 - COM:
   . Removed the ability to import case-insensitive constants from type

Zend/tests/add_006.phpt

@@ -11,9 +11,12 @@ $s2 = "876222numeric";
 $s3 = "48474874";
 $s4 = "25.68";
 
-$c = $i + $s1;
-var_dump($c);
-
+try {
+    $c = $i + $s1;
+    var_dump($c);
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 $c = $i + $s2;
 var_dump($c);
 
@@ -23,8 +26,12 @@ var_dump($c);
 $c = $i + $s4;
 var_dump($c);
 
-$c = $s1 + $i;
-var_dump($c);
+try {
+    $c = $s1 + $i;
+    var_dump($c);
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 
 $c = $s2 + $i;
 var_dump($c);
@@ -38,18 +45,15 @@ var_dump($c);
 echo "Done\n";
 ?>
 --EXPECTF--
-Warning: A non-numeric value encountered in %s on line %d
-int(75636)
+Unsupported operand types: int + string
 
-Notice: A non well formed numeric value encountered in %s on line %d
+Warning: A non-numeric value encountered in %s on line %d
 int(951858)
 int(48550510)
 float(75661.68)
+Unsupported operand types: string + int
 
 Warning: A non-numeric value encountered in %s on line %d
-int(75636)
-
-Notice: A non well formed numeric value encountered in %s on line %d
 int(951858)
 int(48550510)
 float(75661.68)

Zend/tests/bug24773.phpt

@@ -6,7 +6,7 @@ Bug #24773 (unset() of integers treated as arrays causes a crash)
     unset($array["lvl1"]["lvl2"]["b"]);
 ?>
 --EXPECTF--
-Fatal error: Uncaught Error: Cannot use string offset as an array in %s:%d
+Fatal error: Uncaught TypeError: Cannot access offset of type string on string in %s:%d
 Stack trace:
 #0 {main}
   thrown in %s on line %d

Zend/tests/bug31098.phpt

@@ -17,16 +17,28 @@ var_dump(isset($a['b']));
 
 $simpleString = "Bogus String Text";
 echo isset($simpleString->wrong)?"bug\n":"ok\n";
-echo isset($simpleString["wrong"])?"bug\n":"ok\n";
+try {
+    echo isset($simpleString["wrong"])?"bug\n":"ok\n";
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 echo isset($simpleString[-20])?"bug\n":"ok\n";
 echo isset($simpleString[0])?"ok\n":"bug\n";
 echo isset($simpleString["0"])?"ok\n":"bug\n";
 echo isset($simpleString["16"])?"ok\n":"bug\n";
 echo isset($simpleString["17"])?"bug\n":"ok\n";
 echo $simpleString->wrong === null?"ok\n":"bug\n";
-echo $simpleString["wrong"] === "B"?"ok\n":"bug\n";
+try {
+    echo $simpleString["wrong"] === "B"?"ok\n":"bug\n";
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 echo $simpleString["0"] === "B"?"ok\n":"bug\n";
-$simpleString["wrong"] = "f";
+try {
+    $simpleString["wrong"] = "f";
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 echo $simpleString["0"] === "f"?"ok\n":"bug\n";
 ?>
 --EXPECTF--
@@ -46,10 +58,7 @@ ok
 
 Warning: Attempt to read property "wrong" on string in %s on line %d
 ok
-
-Warning: Illegal string offset "wrong" in %s on line %d
-ok
+Cannot access offset of type string on string
 ok
-
-Warning: Illegal string offset "wrong" in %s on line %d
+Cannot access offset of type string on string
 ok

Zend/tests/bug39018_2.phpt

@@ -8,11 +8,8 @@ error_reporting(E_ALL);
 $foo = 'test';
 $x = @$foo[6];
 
-print @($foo[100] + $foo[130]);
-
-print "\nDone\n";
+var_dump(@($foo[100] . $foo[130]));
 
 ?>
 --EXPECT--
-0
-Done
+string(0) ""

Zend/tests/bug53432.phpt

@@ -16,7 +16,11 @@ var_dump($str[-1] = 'a');
 var_dump($str);
 
 $str = '';
-var_dump($str['foo'] = 'a');
+try {
+    var_dump($str['foo'] = 'a');
+} catch (\TypeError $e) {
+    echo $e->getMessage() . \PHP_EOL;
+}
 var_dump($str);
 
 $str = '';
@@ -53,9 +57,7 @@ string(6) "     a"
 Warning: Illegal string offset -1 in %s on line %d
 NULL
 string(0) ""
-
-Warning: Illegal string offset "foo" in %s on line %d
-string(1) "a"
+Cannot access offset of type string on string
 string(1) "a"
 Error: [] operator not supported for strings
 string(0) ""

Zend/tests/bug64578.phpt

@@ -5,10 +5,10 @@ Bug #64578 (debug_backtrace in set_error_handler corrupts zend heap: segfault)
 
 set_error_handler(function($no, $err) { var_dump($err); });
 
-function x($s) { $s['a'] = 1; };
+function x($s) { $s['2a'] = 1; };
 $y = '1';
 x($y);
 print_r($y);
 --EXPECT--
-string(25) "Illegal string offset "a""
+string(26) "Illegal string offset "2a""
 1

Zend/tests/bug72057.phpt

@@ -4,15 +4,15 @@ Bug #73792 (invalid foreach loop hangs script)
 <?php
 $a = 'aaa';
 
-foreach ($a['bbb'] as &$value) {
+foreach ($a['2bbb'] as &$value) {
     echo 'loop';
 }
 
 unset($value);
 echo 'done';
 ?>
 --EXPECTF--
-Warning: Illegal string offset "bbb" in %s on line %d
+Warning: Illegal string offset "2bbb" in %s on line %d
 
 Fatal error: Uncaught Error: Cannot iterate on string offsets by reference in %sbug73792.php:4
 Stack trace:

Zend/tests/bug73792.phpt

@@ -7,10 +7,10 @@ set_error_handler(function ($severity, $message, $file, $line) {
 });
 
 $x = "foo";
-$y = &$x["bar"];
+$y = &$x["2bar"];
 ?>
 --EXPECTF--
-Fatal error: Uncaught Exception: Illegal string offset "bar" in %s:%d
+Fatal error: Uncaught Exception: Illegal string offset "2bar" in %s:%d
 Stack trace:
 #0 %sbug76534.php(%d): {closure}(2, 'Illegal string ...', '%s', %d)
 #1 {main}