fix PyMappingProxy to get only mappiung type

Snowapril · Snowapril · commit 1eb67b924173 · 2021-09-23T23:33:10.000+09:00
According to [`docs`](https://docs.python.org/3/library/types.html?highlight=mappingproxy#types.MappingProxyType) and [`cpython implementation`](https://github.com/python/cpython/blob/3.9/Objects/descrobject.c#L1190), mapping proxy type must created only with mapping type. As this PR implements mapping protocol, I used it to fix it. Signed-off-by: snowapril <sinjihng@gmail.com>
diff --git a/vm/src/builtins/mappingproxy.rs b/vm/src/builtins/mappingproxy.rs
@@ -6,8 +6,8 @@ use crate::iterator;
 use crate::slots::{AsMapping, Iterable, SlotConstructor};
 use crate::vm::VirtualMachine;
 use crate::{
-    IntoPyObject, ItemProtocol, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue,
-    TryFromObject, TypeProtocol,
+    IdProtocol, IntoPyObject, ItemProtocol, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult,
+    PyValue, TryFromObject, TypeProtocol,
 };
 
 #[pyclass(module = false, name = "mappingproxy")]
@@ -40,10 +40,20 @@ impl SlotConstructor for PyMappingProxy {
     type Args = PyObjectRef;
 
     fn py_new(cls: PyTypeRef, mapping: Self::Args, vm: &VirtualMachine) -> PyResult {
-        Self {
-            mapping: MappingProxyInner::Dict(mapping),
+        if !PyMapping::check(cls, vm)
+            || cls.is(&vm.ctx.types.list_type)
+            || cls.is(&vm.ctx.types.tuple_type)
+        {
+            Err(vm.new_type_error(format!(
+                "mappingproxy() argument must be a mapping, not {}",
+                cls
+            )))
+        } else {
+            Self {
+                mapping: MappingProxyInner::Dict(mapping),
+            }
+            .into_pyresult_with_type(vm, cls)
         }
-        .into_pyresult_with_type(vm, cls)
     }
 }
 
