Allow Mojo structs as map keys

mojo/public/tools/bindings/generators/mojom_cpp_generator.py

Index: mojo/public/tools/bindings/generators/mojom_cpp_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
index de906690344d6b1db2664376002d81b77bae5c6a..901405bb5398ffbc179e4b0efd9a3ffef7a826d2 100644
--- a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
@@ -172,6 +172,44 @@ def IsNativeOnlyKind(kind):
   return (mojom.IsStructKind(kind) or mojom.IsEnumKind(kind)) and \
       kind.native_only
 
+
+def IsHashableKind(kind):
+  """Check if the kind can be hashed.
+
+  Args:
+    kind: {Kind} The kind to check.
+
+  Returns:
+    {bool} True if a value of this kind can be hashed.
+  """
+  checked = set()
+  def Check(kind):
+    if kind.spec in checked:
+      return True
+    checked.add(kind.spec)
+    if mojom.IsNullableKind(kind):
+      return False
+    elif mojom.IsStructKind(kind):
+      if (kind.native_only or
+          (IsTypemappedKind(kind) and
+           not _current_typemap[GetFullMojomNameForKind(kind)]["hashable"])):
+        return False
+      return all(Check(field.kind) for field in kind.fields)
+    elif mojom.IsUnionKind(kind):
+      return all(Check(field.kind) for field in kind.fields)
+    elif mojom.IsAnyHandleKind(kind):
+      return False
+    elif mojom.IsAnyInterfaceKind(kind):
+      return False
+    elif mojom.IsArrayKind(kind):
+      return False
+    elif mojom.IsMapKind(kind):
+      return False
+    else:
+      return True
+  return Check(kind)
+
+
 def GetNativeTypeName(typemapped_kind):
   return _current_typemap[GetFullMojomNameForKind(typemapped_kind)]["typename"]
 
@@ -465,6 +503,7 @@ class Generator(generator.Generator):
 
   cpp_filters = {
     "constant_value": ConstantValue,
+    "contains_handles": mojom.ContainsHandles,
     "contains_move_only_members": ContainsMoveOnlyMembers,
     "cpp_wrapper_param_type": GetCppWrapperParamType,
     "cpp_data_view_type": GetCppDataViewType,
@@ -493,6 +532,7 @@ class Generator(generator.Generator):
     "is_any_interface_kind": mojom.IsAnyInterfaceKind,
     "is_any_handle_or_interface_kind": mojom.IsAnyHandleOrInterfaceKind,
     "is_associated_kind": mojom.IsAssociatedKind,
+    "is_hashable": IsHashableKind,
     "is_map_kind": mojom.IsMapKind,
     "is_nullable_kind": mojom.IsNullableKind,
     "is_object_kind": mojom.IsObjectKind,