Fix outdated string to number comparison rules in min() and max() - #5914

Fixes #2687

The issue is about one comment in the max() example, but while checking it I ran every claim and every example on both pages against PHP 8.4.26, and there are four things that still describe the pre 8.0 semantics.

1. The note in the description, on both pages

For instance, a non-numeric string will be compared to an int as though it were 0

Since PHP 8.0 it works the other way around. The int is cast to string and the values are compared as strings:

var_dump("hello" == 0);      // bool(false)
var_dump("hello" <=> 0);     // int(1)
var_dump("hello" <=> "0");   // int(1)   same result, the int became a string

2. The return values section, on both pages

If multiple values of different types evaluate as equal (e.g. 0 and 'abc')

var_dump(0 == "abc");   // bool(false)

I replaced it with 0 and false, which still evaluate as equal, and the rule itself still holds:

var_dump(0 == false);     // bool(true)
var_dump(max(0, false));  // int(0)
var_dump(max(false, 0));  // bool(false)

3. The 'hello' example, on both pages — this is the one from the issue

// Here we are comparing -1 < 0, so 'hello' is the highest value

The result is still correct, but not for that reason:

var_dump(max("hello", -1));     // string(5) "hello"   correct
var_dump("hello" == 0);         // bool(false)         the stated reason is not
var_dump("hello" <=> "-1");     // int(1)              "h" (104) > "-" (45)

4. A documented output in min() that is now wrong

$val = min('string', array(2, 5, 7), 42);   // string

var_dump(min("string", array(2,5,7), 42));   // int(42)

It returns 42. The array is still never returned, that part of the comment is correct, but of the two remaining values 42 is cast to the string "42" when compared with the non-numeric string 'string', and "42" is lower than "string". Before 8.0 'string' became 0, so 0 < 42 and 'string' was the lowest.

What I did not change

I ran the other fourteen examples on both pages, the arrays, the booleans and NULL ones, and the basic usages. They all still produce what the manual says, so I left them alone.

Worth noting

The changelog on both pages already says:

8.0.0 — As string to number comparisons were changed, max() no longer returns a different value based on the argument order in those cases.

So the pages already acknowledge the change, only the description, the return values and the examples were never updated to match.