Warn when coercing NAN to other types

RFC: https://wiki.php.net/rfc/warnings-php-8-5#coercing_nan_to_other_types

Author: Girgias

Zend/tests/type_coercion/nan_to_other.phpt

@@ -40,27 +40,53 @@ foreach ($types as $type) {
 ?>
 --EXPECTF--
 float(NAN)
+
+Warning: unexpected NAN value was coerced to bool in %s on line %d
 bool(true)
+
+Warning: unexpected NAN value was coerced to string in %s on line %d
 string(3) "NAN"
+
+Warning: unexpected NAN value was coerced to int in %s on line %d
 int(0)
+
+Warning: unexpected NAN value was coerced to bool in %s on line %d
 bool(true)
+
+Warning: unexpected NAN value was coerced to string in %s on line %d
 string(3) "NAN"
+
+Warning: unexpected NAN value was coerced to array in %s on line %d
 array(1) {
   [0]=>
   float(NAN)
 }
+
+Warning: unexpected NAN value was coerced to object in %s on line %d
 object(stdClass)#%d (1) {
   ["scalar"]=>
   float(NAN)
 }
+
+Warning: unexpected NAN value was coerced to null in %s on line %d
 NULL
+
+Warning: unexpected NAN value was coerced to bool in %s on line %d
 bool(true)
+
+Warning: unexpected NAN value was coerced to int in %s on line %d
 int(0)
+
+Warning: unexpected NAN value was coerced to string in %s on line %d
 string(3) "NAN"
+
+Warning: unexpected NAN value was coerced to array in %s on line %d
 array(1) {
   [0]=>
   float(NAN)
 }
+
+Warning: unexpected NAN value was coerced to object in %s on line %d
 object(stdClass)#%d (1) {
   ["scalar"]=>
   float(NAN)

Zend/zend_operators.c

@@ -669,6 +669,9 @@ ZEND_API void ZEND_FASTCALL convert_to_double(zval *op) /* {{{ */
 
 ZEND_API void ZEND_FASTCALL convert_to_null(zval *op) /* {{{ */
 {
+	if (UNEXPECTED(Z_TYPE_P(op) == IS_DOUBLE && zend_isnan(Z_DVAL_P(op)))) {
+		zend_nan_coerced_to_type_warning(IS_NULL);
+	}
 	zval_ptr_dtor(op);
 	ZVAL_NULL(op);
 }
@@ -697,6 +700,9 @@ ZEND_API void ZEND_FASTCALL convert_to_boolean(zval *op) /* {{{ */
 			ZVAL_BOOL(op, Z_LVAL_P(op) ? 1 : 0);
 			break;
 		case IS_DOUBLE:
+			if (UNEXPECTED(zend_isnan(Z_DVAL_P(op)))) {
+				zend_nan_coerced_to_type_warning(_IS_BOOL);
+			}
 			ZVAL_BOOL(op, Z_DVAL_P(op) ? 1 : 0);
 			break;
 		case IS_STRING:
@@ -810,6 +816,9 @@ ZEND_API bool ZEND_FASTCALL _try_convert_to_string(zval *op) /* {{{ */
 
 static void convert_scalar_to_array(zval *op) /* {{{ */
 {
+	if (UNEXPECTED(Z_TYPE_P(op) == IS_DOUBLE && zend_isnan(Z_DVAL_P(op)))) {
+		zend_nan_coerced_to_type_warning(IS_ARRAY);
+	}
 	HashTable *ht = zend_new_array(1);
 	zend_hash_index_add_new(ht, 0, op);
 	ZVAL_ARR(op, ht);
@@ -892,6 +901,11 @@ ZEND_API void ZEND_FASTCALL convert_to_object(zval *op) /* {{{ */
 		case IS_REFERENCE:
 			zend_unwrap_reference(op);
 			goto try_again;
+		case IS_DOUBLE:
+			if (UNEXPECTED(zend_isnan(Z_DVAL_P(op)))) {
+				zend_nan_coerced_to_type_warning(IS_OBJECT);
+			}
+			ZEND_FALLTHROUGH;
 		default: {
 			zval tmp;
 			ZVAL_COPY_VALUE(&tmp, op);
@@ -912,6 +926,11 @@ ZEND_API void ZEND_COLD zend_incompatible_string_to_long_error(const zend_string
 	zend_error(E_DEPRECATED, "Implicit conversion from float-string \"%s\" to int loses precision", ZSTR_VAL(s));
 }
 
+ZEND_API void ZEND_COLD zend_nan_coerced_to_type_warning(uint8_t type)
+{
+	zend_error(E_WARNING, "unexpected NAN value was coerced to %s", zend_get_type_by_const(type));
+}
+
 ZEND_API zend_long ZEND_FASTCALL zval_get_long_func(const zval *op, bool is_strict) /* {{{ */
 {
 try_again:
@@ -3543,6 +3562,9 @@ ZEND_API zend_string* ZEND_FASTCALL zend_double_to_str(double num)
 	int precision = (int) EG(precision);
 	zend_gcvt(num, precision ? precision : 1, '.', 'E', buf);
 	zend_string *str =  zend_string_init(buf, strlen(buf), 0);
+	if (UNEXPECTED(zend_string_equals_literal(str, "NAN"))) {
+		zend_nan_coerced_to_type_warning(IS_STRING);
+	}
 	GC_ADD_FLAGS(str, IS_STR_VALID_UTF8);
 	return str;
 }

Zend/zend_operators.h

@@ -115,11 +115,18 @@ ZEND_API const char* ZEND_FASTCALL zend_memnrstr_ex(const char *haystack, const
 #	define ZEND_DOUBLE_FITS_LONG(d) (!((d) >= (double)ZEND_LONG_MAX || (d) < (double)ZEND_LONG_MIN))
 #endif
 
+ZEND_API void zend_incompatible_double_to_long_error(double d);
+ZEND_API void zend_incompatible_string_to_long_error(const zend_string *s);
+ZEND_API void ZEND_COLD zend_nan_coerced_to_type_warning(uint8_t type);
+
 ZEND_API zend_long ZEND_FASTCALL zend_dval_to_lval_slow(double d);
 
 static zend_always_inline zend_long zend_dval_to_lval(double d)
 {
 	if (UNEXPECTED(!zend_finite(d)) || UNEXPECTED(zend_isnan(d))) {
+		if (zend_isnan(d)) {
+			zend_nan_coerced_to_type_warning(IS_LONG);
+		}
 		return 0;
 	} else if (!ZEND_DOUBLE_FITS_LONG(d)) {
 		return zend_dval_to_lval_slow(d);
@@ -131,6 +138,9 @@ static zend_always_inline zend_long zend_dval_to_lval(double d)
 static zend_always_inline zend_long zend_dval_to_lval_cap(double d)
 {
 	if (UNEXPECTED(!zend_finite(d)) || UNEXPECTED(zend_isnan(d))) {
+		if (zend_isnan(d)) {
+			zend_nan_coerced_to_type_warning(IS_LONG);
+		}
 		return 0;
 	} else if (!ZEND_DOUBLE_FITS_LONG(d)) {
 		return (d > 0 ? ZEND_LONG_MAX : ZEND_LONG_MIN);
@@ -143,9 +153,6 @@ static zend_always_inline bool zend_is_long_compatible(double d, zend_long l) {
 	return (double)l == d;
 }
 
-ZEND_API void zend_incompatible_double_to_long_error(double d);
-ZEND_API void zend_incompatible_string_to_long_error(const zend_string *s);
-
 static zend_always_inline zend_long zend_dval_to_lval_safe(double d)
 {
 	zend_long l = zend_dval_to_lval(d);
@@ -405,6 +412,9 @@ static zend_always_inline bool i_zend_is_true(const zval *op)
 			}
 			break;
 		case IS_DOUBLE:
+			if (UNEXPECTED(zend_isnan(Z_DVAL_P(op)))) {
+				zend_nan_coerced_to_type_warning(_IS_BOOL);
+			}
 			if (Z_DVAL_P(op)) {
 				result = 1;
 			}