[GR-40390] copy the storage of sets for shallow copy. fixes oracle/graal#4816

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/test_set.py

@@ -528,3 +528,17 @@ def test_inplace_ops_mutate():
         exec(f"a {op}= b", v)
         assert v['a'] is s1
         assert s1 == eval(f"a {op} b", {'a': {1, 2}, 'b': {1, 3}})
+
+
+def test_graal_4816():
+    from copy import copy
+
+    def do_something(numbers):
+        assert len(numbers)
+
+    foo = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
+
+    for _ in copy(foo):
+        foo.pop()
+        if foo:
+            do_something(foo)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/set/SetBuiltins.java

@@ -138,9 +138,10 @@ PNone fail(@SuppressWarnings("unused") VirtualFrame frame, @SuppressWarnings("un
     @GenerateNodeFactory
     public abstract static class CopyNode extends PythonBuiltinNode {
 
-        @Specialization
-        PSet doSet(@SuppressWarnings("unused") VirtualFrame frame, PSet self) {
-            return factory().createSet(self.getDictStorage());
+        @Specialization(limit = "1")
+        PSet doSet(@SuppressWarnings("unused") VirtualFrame frame, PSet self,
+                        @CachedLibrary("self.getDictStorage()") HashingStorageLibrary lib) {
+            return factory().createSet(lib.copy(self.getDictStorage()));
         }
     }