Fix pointer assignment for list/set/dict (pyccel#2038)

Fix the recognition of an alias assign for an expression such as `a = b`
where `a` and `b` are lists/sets/dicts. Fixes pyccel#2008. Fix the printing of
a list/set/dict pointer

Author: EmilyBourne

CHANGELOG.md

@@ -71,6 +71,7 @@ All notable changes to this project will be documented in this file.
 -   #1979 : Fix memory leaks in C due to homogeneous container redefinition.
 -   #1972 : Simplified `printf` statement for Literal String.
 -   #2026 : Fix missing loop in slice assignment.
+-   #2008 : Ensure list/set/dict assignment is recognised as a reference.
 
 ### Changed
 

pyccel/ast/builtins.py

@@ -732,10 +732,8 @@ class PythonListFunction(PyccelFunction):
     def __new__(cls, arg = None):
         if arg is None:
             return PythonList()
-        elif isinstance(arg, PythonList):
-            return arg
         elif isinstance(arg.shape[0], LiteralInteger):
-            return PythonList(*[arg[i] for i in range(arg.shape[0])])
+            return PythonList(*arg)
         else:
             return super().__new__(cls)
 
@@ -838,8 +836,6 @@ class PythonSetFunction(PyccelFunction):
     def __new__(cls, arg = None):
         if arg is None:
             return PythonSet()
-        elif isinstance(arg.class_type, HomogeneousSetType):
-            return arg
         elif isinstance(arg, (PythonList, PythonSet, PythonTuple)):
             return PythonSet(*arg)
         else:

pyccel/codegen/printing/ccode.py

@@ -359,7 +359,7 @@ def is_c_pointer(self, a):
 
         if not isinstance(a, Variable):
             return False
-        return (a.is_alias and not isinstance(a.class_type, HomogeneousContainerType)) \
+        return (a.is_alias and not isinstance(a.class_type, (HomogeneousTupleType, NumpyNDArrayType))) \
                 or a.is_optional or \
                 any(a is bi for b in self._additional_args for bi in b)
 
@@ -1363,10 +1363,9 @@ def get_declare_type(self, expr):
         if rank > 0:
             if isinstance(expr.class_type, (HomogeneousSetType, HomogeneousListType, DictType)):
                 dtype = self.get_c_type(expr.class_type)
-                return dtype
-            if isinstance(expr.class_type, CStackArray):
+            elif isinstance(expr.class_type, CStackArray):
                 return self.get_c_type(expr.class_type.element_type)
-            if isinstance(expr.class_type,(HomogeneousTupleType, NumpyNDArrayType)):
+            elif isinstance(expr.class_type, (HomogeneousTupleType, NumpyNDArrayType)):
                 if expr.rank > 15:
                     errors.report(UNSUPPORTED_ARRAY_RANK, symbol=expr, severity='fatal')
                 self.add_import(c_imports['ndarrays'])
@@ -1741,6 +1740,8 @@ def _print_Allocate(self, expr):
 
     def _print_Deallocate(self, expr):
         if isinstance(expr.variable.class_type, (HomogeneousListType, HomogeneousSetType, DictType)):
+            if expr.variable.is_alias:
+                return ''
             variable_address = self._print(ObjectAddress(expr.variable))
             container_type = self.get_c_type(expr.variable.class_type)
             return f'{container_type}_drop({variable_address});\n'

pyccel/codegen/printing/fcode.py

@@ -1981,7 +1981,7 @@ def _print_AliasAssign(self, expr):
         # TODO improve
         op = '=>'
         shape_code = ''
-        if lhs.rank > 0:
+        if isinstance(lhs.class_type, (NumpyNDArrayType, HomogeneousTupleType)):
             shape_code = ', '.join('0:' for i in range(lhs.rank))
             shape_code = '({s_c})'.format(s_c = shape_code)
 

pyccel/parser/semantic.py

@@ -1401,7 +1401,8 @@ def _ensure_target(self, rhs, d_lhs):
             d_lhs['memory_handling'] = 'alias'
             rhs.internal_var.is_target = True
 
-        if isinstance(rhs, Variable) and (rhs.is_ndarray or isinstance(rhs.class_type, CustomDataType)):
+        if isinstance(rhs, Variable) and (rhs.rank > 0 or isinstance(rhs.class_type, CustomDataType)) \
+                and not isinstance(rhs.class_type, (TupleType, StringType)):
             d_lhs['memory_handling'] = 'alias'
             rhs.is_target = not rhs.is_alias
 

tests/epyccel/test_epyccel_dicts.py

@@ -191,3 +191,16 @@ def dict_contains():
     python_result = dict_contains()
     assert isinstance(python_result, type(pyccel_result))
     assert python_result == pyccel_result
+
+def test_dict_ptr(python_only_language):
+    def dict_ptr():
+        a = {1:1.0, 2:2.0, 3:3.0}
+        b = a
+        c = b.pop(2)
+        return len(a), len(b), c
+
+    epyc_func = epyccel(dict_ptr, language = python_only_language)
+    pyccel_result = epyc_func()
+    python_result = dict_ptr()
+    assert isinstance(python_result, type(pyccel_result))
+    assert python_result == pyccel_result

tests/epyccel/test_epyccel_lists.py

@@ -756,3 +756,16 @@ def list_contains():
     python_result = list_contains()
     assert isinstance(python_result, type(pyccel_result))
     assert python_result == pyccel_result
+
+def test_dict_ptr(language):
+    def list_ptr():
+        a = [1, 3, 4, 7, 10, 3]
+        b = a
+        b.append(22)
+        return len(a), len(b)
+
+    epyc_list_ptr = epyccel(list_ptr, language = language)
+    pyccel_result = epyc_list_ptr()
+    python_result = list_ptr()
+    assert isinstance(python_result, type(pyccel_result))
+    assert python_result == pyccel_result

tests/epyccel/test_epyccel_sets.py

@@ -520,3 +520,15 @@ def union_int():
     pyccel_result = epyccel_func()
     python_result = union_int()
     assert python_result == pyccel_result
+
+def test_set_ptr(language):
+    def set_ptr():
+        a = {1,2,3,4,5,6,7,8}
+        b = a
+        b.pop()
+        return len(a), len(b)
+
+    epyccel_func = epyccel(set_ptr, language = language)
+    pyccel_result = epyccel_func()
+    python_result = set_ptr()
+    assert python_result == pyccel_result