NSString: fix -commonPrefixWithString:options: behaviour

gnustep · Oct 28, 2024 · 878e3a0 · 878e3a0
1 parent f133f1d
commit 878e3a0
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diff --git a/Source/NSString.m b/Source/NSString.m
@@ -3227,6 +3227,11 @@ - (NSUInteger) hash
 - (NSString*) commonPrefixWithString: (NSString*)aString
 			     options: (NSUInteger)mask
 {
+  // Return empty string to match behaviour on macOS
+  if (nil == aString)
+    {
+      return @"";
+    }
   if (mask & NSLiteralSearch)
     {
       int prefix_len = 0;

diff --git a/Tests/base/NSString/basic.m b/Tests/base/NSString/basic.m
@@ -144,6 +144,9 @@ int main()
   PASS([@"" isEqual: nil] == NO, "an empty string is not null");
   PASS([@"" isEqualToString: nil] == NO, "an empty string is not null");
 
+  s = [@"test" commonPrefixWithString: nil options: 0];
+  PASS_EQUAL(s, @"", "Common prefix of some string with nil is empty string");
+
   [arp release]; arp = nil;
   return 0;
 }