add mapping type check to mappingproxy

Snowapril · Snowapril · commit ee0432670b49 · 2021-09-29T15:24:42.000+09:00
As in cpython implementation there exists argument type checking before
create mapping proxy like below.
```c
if (!PyMapping_Check(mapping)
    || PyList_Check(mapping)
    || PyTuple_Check(mapping))
	// print error
...
```

Signed-off-by: snowapril &lt;sinjihng@gmail.com&gt;
diff --git a/vm/src/builtins/dict.rs b/vm/src/builtins/dict.rs
@@ -926,7 +926,15 @@ pub struct PyMapping {
         Option<fn(PyObjectRef, PyObjectRef, Option<PyObjectRef>, &VirtualMachine) -> PyResult<()>>,
 }
 
-impl PyMapping {}
+impl PyMapping {
+    pub fn check(cls: &PyObjectRef, vm: &VirtualMachine) -> bool {
+        if let Ok(mapping) = PyMapping::try_from_borrowed_object(vm, cls) {
+            mapping.subscript.is_some()
+        } else {
+            false
+        }
+    }
+}
 
 impl TryFromBorrowedObject for PyMapping {
     fn try_from_borrowed_object(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<Self> {
diff --git a/vm/src/builtins/mappingproxy.rs b/vm/src/builtins/mappingproxy.rs
@@ -1,4 +1,4 @@
-use super::{PyDict, PyStrRef, PyTypeRef};
+use super::{PyDict, PyList, PyStrRef, PyTuple, PyTypeRef};
 use crate::{
     builtins::dict::PyMapping,
     function::OptionalArg,
@@ -38,10 +38,20 @@ 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(&mapping, vm)
+            || mapping.payload_if_subclass::<PyList>(vm).is_some()
+            || mapping.payload_if_subclass::<PyTuple>(vm).is_some()
+        {
+            Err(vm.new_type_error(format!(
+                "mappingproxy() argument must be a mapping, not {}",
+                mapping.class()
+            )))
+        } else {
+            Self {
+                mapping: MappingProxyInner::Dict(mapping),
+            }
+            .into_pyresult_with_type(vm, cls)
         }
-        .into_pyresult_with_type(vm, cls)
     }
 }
 
