ext/intl: Fix Collator sort conversion error handling (#22893)

Report UTF-8/UTF-16 conversion failures from Collator sort comparisons through
the intl error mechanism.

Previously, these paths emitted a warning and continued with an empty string.

Keep the input array unchanged when sorting cannot complete, preserve the
active collator state across nested sorts, and stop invoking further
comparisons after a conversion failure.

Co-authored-by: David CARLIER <devnexen@gmail.com>

Author: LamentXU123

NEWS

@@ -7,6 +7,12 @@ PHP                                                                        NEWS
     (Weilin Du)
   . Added gmp_powm_sec(). (Weilin Du)
 
+- Intl:
+  . Fixed Collator::sort(), collator_sort(), Collator::asort(), and
+    collator_asort() to report UTF-8/UTF-16 conversion errors through the intl
+    error handler instead of emitting a warning and continuing with an empty
+    string. (Weilin Du)
+
 30 Jul 2026, PHP 8.6.0alpha3
 
 - Core:

UPGRADING

@@ -76,6 +76,11 @@ PHP 8.6 UPGRADE NOTES
     IntlDateFormatter::localtime()/datefmt_localtime() now raise a TypeError
     when the offset argument is not of type int instead of silently converting
     the value.
+  . Collator::sort(), collator_sort(), Collator::asort(), and
+    collator_asort() now report UTF-8/UTF-16 conversion failures during
+    comparison through the intl error mechanism and return false. With
+    intl.use_exceptions enabled, these failures throw IntlException. Previously,
+    these paths emitted a warning and compared the value as an empty string.
 
 - PCNTL:
   . pcntl_alarm() now raises a ValueError if the seconds argument is

ext/intl/collator/collator_convert.cpp

@@ -38,6 +38,20 @@ extern "C" {
 			return retval;                       \
 	}
 
+static void collator_set_conversion_error(UErrorCode status, const char *message)
+{
+	if (U_SUCCESS(status)) {
+		status = U_MEMORY_ALLOCATION_ERROR;
+	}
+
+	ZEND_ASSERT(INTL_G(current_collator_error) != nullptr);
+	intl_error *err = INTL_G(current_collator_error);
+	intl_error_reset(err);
+	err->code = status;
+	err->custom_error_message = zend_string_init(
+		message, strlen(message), false);
+}
+
 /* {{{ collator_convert_hash_item_from_utf8_to_utf16 */
 static void collator_convert_hash_item_from_utf8_to_utf16(
 	HashTable* hash, zval *hashData, zend_string *hashKey, zend_ulong hashIndex,
@@ -166,11 +180,12 @@ U_CFUNC zval* collator_convert_zstr_utf16_to_utf8( zval* utf16_zval, zval *rv )
 	u8str = intl_convert_utf16_to_utf8(
 		(UChar*) Z_STRVAL_P(utf16_zval), UCHARS( Z_STRLEN_P(utf16_zval) ), &status );
 	if( !u8str ) {
-		php_error( E_WARNING, "Error converting utf16 to utf8 in collator_convert_zval_utf16_to_utf8()" );
-		ZVAL_EMPTY_STRING( rv );
-	} else {
-		ZVAL_NEW_STR( rv, u8str );
+		collator_set_conversion_error(status, "Error converting string from UTF-16 to UTF-8");
+		ZVAL_NULL( rv );
+		return nullptr;
 	}
+
+	ZVAL_NEW_STR( rv, u8str );
 	return rv;
 }
 /* }}} */
@@ -183,11 +198,9 @@ U_CFUNC zend_string *collator_convert_zstr_utf8_to_utf16(zend_string *utf8_str)
 	zend_string *zstr = intl_convert_utf8_to_utf16_zstr(
 			ZSTR_VAL(utf8_str), ZSTR_LEN(utf8_str),
 			&status);
-	// FIXME Or throw error or use intl internal error handler
 	if (U_FAILURE(status)) {
-		php_error(E_WARNING,
-			"Error casting object to string in collator_convert_zstr_utf8_to_utf16()");
-		zstr = ZSTR_EMPTY_ALLOC();
+		collator_set_conversion_error(status, "Error converting string from UTF-8 to UTF-16");
+		return nullptr;
 	}
 
 	return zstr;
@@ -214,23 +227,31 @@ U_CFUNC zval* collator_convert_object_to_string( zval* obj, zval *rv )
 	{
 		/* cast_object failed => bail out. */
 		zval_ptr_dtor( zstr );
+		ZVAL_NULL( zstr );
+		if( EG(exception) ) {
+			return nullptr;
+		}
 		COLLATOR_CONVERT_RETURN_FAILED( obj );
 	}
 
 	/* Object wasn't successfully converted => bail out. */
 	if( zstr == nullptr )
 	{
+		if( EG(exception) ) {
+			return nullptr;
+		}
 		COLLATOR_CONVERT_RETURN_FAILED( obj );
 	}
 
 	/* Convert the string to UTF-16. */
 	zend_string *converted_str = intl_convert_utf8_to_utf16_zstr(
 			Z_STRVAL_P( zstr ), Z_STRLEN_P( zstr ),
 			&status );
-	// FIXME Or throw error or use intl internal error handler
 	if( U_FAILURE( status ) ) {
-		php_error( E_WARNING, "Error casting object to string in collator_convert_object_to_string()" );
-		converted_str = ZSTR_EMPTY_ALLOC();
+		collator_set_conversion_error(status, "Error converting object string from UTF-8 to UTF-16");
+		zval_ptr_dtor( zstr );
+		ZVAL_NULL( zstr );
+		return nullptr;
 	}
 
 	/* Cleanup zstr to hold utf16 string. */
@@ -339,7 +360,11 @@ U_CFUNC zend_string *collator_zval_to_string(zval *arg)
 		return zend_string_copy(Z_STR_P(arg));
 	}
 
-	zend_string *utf8_str = zval_get_string(arg);
+	zend_string *utf8_str = zval_try_get_string(arg);
+	if (utf8_str == nullptr) {
+		return nullptr;
+	}
+
 	zend_string *utf16_str = collator_convert_zstr_utf8_to_utf16(utf8_str);
 	zend_string_release(utf8_str);
 	return utf16_str;

ext/intl/collator/collator_sort.cpp

@@ -50,6 +50,17 @@ static const size_t DEF_SORT_KEYS_INDX_BUF_INCREMENT = 1048576;
 
 static const size_t DEF_UTF16_BUF_SIZE = 1024;
 
+static void collator_report_sort_error(Collator_object *co, const intl_error *sort_error)
+{
+	if (sort_error->custom_error_message) {
+		intl_errors_set(
+			COLLATOR_ERROR_P(co), sort_error->code,
+			ZSTR_VAL(sort_error->custom_error_message));
+	} else {
+		intl_errors_set_code(COLLATOR_ERROR_P(co), sort_error->code);
+	}
+}
+
 /* {{{ collator_regular_compare_function */
 static int collator_regular_compare_function(zval *result, zval *op1, zval *op2)
 {
@@ -59,12 +70,20 @@ static int collator_regular_compare_function(zval *result, zval *op1, zval *op2)
 	zval norm1, norm2;
 	zval *num1_p = nullptr, *num2_p = nullptr;
 	zval *norm1_p = nullptr, *norm2_p = nullptr;
-	zval *str1_p, *str2_p;
+	zval *str1_p = nullptr, *str2_p = nullptr;
 
 	ZVAL_NULL(&str1);
 	str1_p  = collator_convert_object_to_string( op1, &str1 );
+	if( str1_p == nullptr ) {
+		return FAILURE;
+	}
+
 	ZVAL_NULL(&str2);
 	str2_p  = collator_convert_object_to_string( op2, &str2 );
+	if( str2_p == nullptr ) {
+		rc = FAILURE;
+		goto cleanup;
+	}
 
 	/* If both args are strings AND either of args is not numeric string
 	 * then use ICU-compare. Otherwise PHP-compare. */
@@ -90,9 +109,17 @@ static int collator_regular_compare_function(zval *result, zval *op1, zval *op2)
 				 * just convert it to utf8.
 				 */
 				norm1_p = collator_convert_zstr_utf16_to_utf8( str1_p, &norm1 );
+				if( norm1_p == nullptr ) {
+					rc = FAILURE;
+					goto cleanup;
+				}
 
 				/* num2 is not set but str2 is string => do normalization. */
 				norm2_p = collator_normalize_sort_argument( str2_p, &norm2 );
+				if( norm2_p == nullptr ) {
+					rc = FAILURE;
+					goto cleanup;
+				}
 			}
 			else
 			{
@@ -109,25 +136,40 @@ static int collator_regular_compare_function(zval *result, zval *op1, zval *op2)
 		{
 			/* num1 is not set if str1 or str2 is not a string => do normalization. */
 			norm1_p = collator_normalize_sort_argument( str1_p, &norm1 );
+			if( norm1_p == nullptr ) {
+				rc = FAILURE;
+				goto cleanup;
+			}
 
 			/* if num1 is not set then num2 is not set as well => do normalization. */
 			norm2_p = collator_normalize_sort_argument( str2_p, &norm2 );
+			if( norm2_p == nullptr ) {
+				rc = FAILURE;
+				goto cleanup;
+			}
 		}
 
 		rc = compare_function( result, norm1_p, norm2_p );
+	}
 
+cleanup:
+	if( norm1_p )
 		zval_ptr_dtor( norm1_p );
+
+	if( norm2_p )
 		zval_ptr_dtor( norm2_p );
-	}
 
 	if( num1_p )
 		zval_ptr_dtor( num1_p );
 
 	if( num2_p )
 		zval_ptr_dtor( num2_p );
 
-	zval_ptr_dtor( str1_p );
-	zval_ptr_dtor( str2_p );
+	if( str1_p )
+		zval_ptr_dtor( str1_p );
+
+	if( str2_p )
+		zval_ptr_dtor( str2_p );
 
 	return rc;
 }
@@ -170,9 +212,16 @@ static int collator_numeric_compare_function(zval *result, zval *op1, zval *op2)
 */
 static int collator_icu_compare_function(zval *result, zval *op1, zval *op2)
 {
-	int rc = SUCCESS;
 	zend_string *str1 = collator_zval_to_string(op1);
+	if( str1 == nullptr ) {
+		return FAILURE;
+	}
+
 	zend_string *str2 = collator_zval_to_string(op2);
+	if( str2 == nullptr ) {
+		zend_string_release(str1);
+		return FAILURE;
+	}
 
 	/* Compare the strings using ICU. */
 	ZEND_ASSERT(INTL_G(current_collator) != nullptr);
@@ -184,7 +233,7 @@ static int collator_icu_compare_function(zval *result, zval *op1, zval *op2)
 	zend_string_release(str1);
 	zend_string_release(str2);
 
-	return rc;
+	return SUCCESS;
 }
 /* }}} */
 
@@ -197,6 +246,11 @@ static int collator_compare_func(Bucket *f, Bucket *s)
 	zval *first = &f->val;
 	zval *second = &s->val;
 
+	ZEND_ASSERT(INTL_G(current_collator_error) != nullptr);
+	if( EG(exception) || U_FAILURE( INTL_ERROR_CODE(*INTL_G(current_collator_error)) ) ) {
+		return 0;
+	}
+
 	if( INTL_G(compare_func)( &result, first, second) == FAILURE )
 		return 0;
 
@@ -260,6 +314,9 @@ static collator_compare_func_t collator_get_compare_function( const zend_long so
 static void collator_sort_internal( int renumber, INTERNAL_FUNCTION_PARAMETERS )
 {
 	UCollator*     saved_collator;
+	intl_error*    saved_collator_error;
+	intl_error     sort_error;
+	collator_compare_func_t saved_compare_func;
 	zval*          array            = nullptr;
 	HashTable*     hash             = nullptr;
 	zend_array*    sorted           = nullptr;
@@ -282,9 +339,6 @@ static void collator_sort_internal( int renumber, INTERNAL_FUNCTION_PARAMETERS )
 		RETURN_THROWS();
 	}
 
-	/* Set 'compare function' according to sort flags. */
-	INTL_G(compare_func) = collator_get_compare_function( sort_flags );
-
 	hash = Z_ARRVAL_P( array );
 
 	/* Copy array, so the in-place modifications will not be visible to the callback function */
@@ -297,15 +351,38 @@ static void collator_sort_internal( int renumber, INTERNAL_FUNCTION_PARAMETERS )
 	}
 	COLLATOR_CHECK_STATUS( co, "Error converting hash from UTF-8 to UTF-16" );
 
+	intl_error_init( &sort_error );
+
 	/* Save specified collator in the request-global (?) variable. */
 	saved_collator = INTL_G( current_collator );
+	saved_collator_error = INTL_G( current_collator_error );
+	saved_compare_func = INTL_G( compare_func );
 	INTL_G( current_collator ) = co->ucoll;
+	INTL_G( current_collator_error ) = &sort_error;
+	INTL_G( compare_func ) = collator_get_compare_function( sort_flags );
 
 	/* Sort specified array. */
 	zend_hash_sort( sorted, collator_compare_func, renumber );
 
 	/* Restore saved collator. */
 	INTL_G( current_collator ) = saved_collator;
+	INTL_G( current_collator_error ) = saved_collator_error;
+	INTL_G( compare_func ) = saved_compare_func;
+
+	if( EG(exception) ) {
+		zend_array_destroy( sorted );
+		intl_error_reset( &sort_error );
+		RETURN_THROWS();
+	}
+
+	if( U_FAILURE( INTL_ERROR_CODE(sort_error) ) ) {
+		zend_array_destroy( sorted );
+		collator_report_sort_error(co, &sort_error);
+		intl_error_reset( &sort_error );
+		RETURN_FALSE;
+	}
+
+	intl_error_reset( &sort_error );
 
 	/* Convert strings in the specified array back to UTF-8. */
 	collator_convert_hash_from_utf16_to_utf8( sorted, COLLATOR_ERROR_CODE_P( co ) );

ext/intl/php_intl.c

@@ -278,6 +278,7 @@ PHP_RINIT_FUNCTION( intl )
 PHP_RSHUTDOWN_FUNCTION( intl )
 {
 	INTL_G(current_collator) = NULL;
+	INTL_G(current_collator_error) = NULL;
 	if (INTL_G(grapheme_iterator)) {
 		grapheme_close_global_iterator(  );
 		INTL_G(grapheme_iterator) = NULL;

ext/intl/php_intl.h

@@ -45,6 +45,7 @@ extern zend_module_entry intl_module_entry;
 
 ZEND_BEGIN_MODULE_GLOBALS(intl)
 	struct UCollator *current_collator;
+	intl_error *current_collator_error;
 	char* default_locale;
 	collator_compare_func_t compare_func;
 	UBreakIterator* grapheme_iterator;

ext/intl/tests/collator_sort_conversion_error.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Collator::sort() reports conversion errors from comparison callbacks
+--EXTENSIONS--
+intl
+--FILE--
+<?php
+class BadString {
+    public function __toString(): string {
+        return "\xFF";
+    }
+}
+
+$coll = new Collator('en_US');
+$array = ['b', new BadString(), 'a'];
+
+var_dump($coll->sort($array, Collator::SORT_STRING));
+var_dump(intl_get_error_code() === U_INVALID_CHAR_FOUND);
+echo intl_get_error_message(), "\n";
+var_dump($coll->getErrorCode() === U_INVALID_CHAR_FOUND);
+echo $coll->getErrorMessage(), "\n";
+?>
+--EXPECT--
+bool(false)
+bool(true)
+Collator::sort(): Error converting string from UTF-8 to UTF-16: U_INVALID_CHAR_FOUND
+bool(true)
+Collator::sort(): Error converting string from UTF-8 to UTF-16: U_INVALID_CHAR_FOUND