ext/standard: Deprecate passing integers outside the interval [0, 255] to chr()

RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_passing_integers_outside_the_interval_0_255_to_chr

Author: Girgias

Zend/zend_compile.c

@@ -4142,17 +4142,19 @@ static zend_result zend_compile_func_defined(znode *result, zend_ast_list *args)
 }
 /* }}} */
 
-static zend_result zend_compile_func_chr(znode *result, zend_ast_list *args) /* {{{ */
+static zend_result zend_compile_func_chr(znode *result, const zend_ast_list *args) /* {{{ */
 {
-
-	if (args->children == 1 &&
-	    args->child[0]->kind == ZEND_AST_ZVAL &&
-	    Z_TYPE_P(zend_ast_get_zval(args->child[0])) == IS_LONG) {
-
-		zend_long c = Z_LVAL_P(zend_ast_get_zval(args->child[0])) & 0xff;
-
+	zval *zint;
+	if (
+		args->children == 1
+		&& args->child[0]->kind == ZEND_AST_ZVAL
+		&& (zint = zend_ast_get_zval(args->child[0]))
+		&& Z_TYPE_P(zint) == IS_LONG
+		&& Z_LVAL_P(zint) >= 0
+		&& Z_LVAL_P(zint) <= 255
+	) {
 		result->op_type = IS_CONST;
-		ZVAL_CHAR(&result->u.constant, c);
+		ZVAL_CHAR(&result->u.constant, Z_LVAL_P(zint));
 		return SUCCESS;
 	} else {
 		return FAILURE;

ext/standard/string.c

@@ -2665,6 +2665,12 @@ PHP_FUNCTION(chr)
 		Z_PARAM_LONG(c)
 	ZEND_PARSE_PARAMETERS_END();
 
+	if (UNEXPECTED(c < 0 || c > 255)) {
+		php_error_docref(NULL, E_DEPRECATED,
+			"Providing a value not in-between 0 and 255 is deprecated,"
+			" this is because a byte value must be in the [0, 255] interval."
+			" The value used will be constrained using %% 256");
+	}
 	c &= 0xff;
 	RETURN_CHAR(c);
 }

ext/standard/tests/strings/chr_out_of_range.phpt

@@ -0,0 +1,15 @@
+--TEST--
+chr() with out of range values
+--FILE--
+<?php
+
+var_dump("\xFF" == chr(-1));
+var_dump("\0" == chr(256));
+
+?>
+--EXPECTF--
+Deprecated: chr(): Providing a value not in-between 0 and 255 is deprecated, this is because a byte value must be in the [0, 255] interval. The value used will be constrained using % 256 in %s on line 3
+bool(true)
+
+Deprecated: chr(): Providing a value not in-between 0 and 255 is deprecated, this is because a byte value must be in the [0, 255] interval. The value used will be constrained using % 256 in %s on line 4
+bool(true)

ext/standard/tests/strings/chr_variation1.phpt

@@ -5,36 +5,17 @@ Test chr() function : usage variations - test values for $ascii argument
 
 echo "*** Testing chr() function: with unexpected inputs for 'ascii' argument ***\n";
 
-//defining a class
-class sample  {
-  public function __toString() {
-    return "sample object";
-  }
-}
-
-//getting the resource
-$file_handle = fopen(__FILE__, "r");
-
 // array with different values for $input
-$inputs =  array (
-
-          // integer values
-/*1*/	  0,
-          1,
-          255,
-          256,
-
-          // float values
-/*5*/	  10.5,
-          -20.5,
-          1.1234e6,
-
-          // boolean values
-/*11*/	  true,
-          false,
-          TRUE,
-          FALSE,
-);
+$inputs = [
+	0,
+	1,
+	255,
+	// float values
+	10.5,
+	// bool values
+	true,
+	false,
+];
 
 // loop through with each element of the $inputs array to test chr() function
 $count = 1;
@@ -44,8 +25,6 @@ foreach($inputs as $input) {
   $count ++;
 }
 
-fclose($file_handle);  //closing the file handle
-
 ?>
 --EXPECTF--
 *** Testing chr() function: with unexpected inputs for 'ascii' argument ***
@@ -56,22 +35,10 @@ string(2) "01"
 -- Iteration 3 --
 string(2) "ff"
 -- Iteration 4 --
-string(2) "00"
--- Iteration 5 --
 
 Deprecated: Implicit conversion from float 10.5 to int loses precision in %s on line %d
 string(2) "0a"
--- Iteration 6 --
-
-Deprecated: Implicit conversion from float -20.5 to int loses precision in %s on line %d
-string(2) "ec"
--- Iteration 7 --
-string(2) "48"
--- Iteration 8 --
-string(2) "01"
--- Iteration 9 --
-string(2) "00"
--- Iteration 10 --
+-- Iteration 5 --
 string(2) "01"
--- Iteration 11 --
+-- Iteration 6 --
 string(2) "00"