diff --git a/pydantic/schema.py b/pydantic/schema.py
--- a/pydantic/schema.py
+++ b/pydantic/schema.py
@@ -4,7 +4,7 @@
 from decimal import Decimal
 from enum import Enum
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Sequence, Set, Tuple, Type, Union, cast
+from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Sequence, Set, Tuple, Type, TypeVar, Union, cast
 from uuid import UUID
 
 import pydantic
@@ -731,7 +731,7 @@ def field_singleton_schema(  # noqa: C901 (ignore complexity)
             ref_prefix=ref_prefix,
             known_models=known_models,
         )
-    if field.type_ is Any:
+    if field.type_ is Any or type(field.type_) == TypeVar:
         return {}, definitions, nested_models  # no restrictions
     if is_callable_type(field.type_):
         raise SkipField(f'Callable {field.name} was excluded from schema since JSON schema has no equivalent type.')

The solution is to allow naked `Dict` and treat it like `dict`.

This was referenced at https://github.com/samuelcolvin/pydantic/issues/545#issuecomment-495943391

PR welcome to fix this.
The solution is to allow naked `Dict` and treat it like `dict`.

This was referenced at https://github.com/samuelcolvin/pydantic/issues/545#issuecomment-495943391

PR welcome to fix this.
diff --git a/tests/test_schema.py b/tests/test_schema.py
--- a/tests/test_schema.py
+++ b/tests/test_schema.py
@@ -11,7 +11,13 @@
 import pytest
 
 from pydantic import BaseModel, Schema, ValidationError, validator
-from pydantic.schema import get_flat_models_from_model, get_flat_models_from_models, get_model_name_map, schema
+from pydantic.schema import (
+    get_flat_models_from_model,
+    get_flat_models_from_models,
+    get_model_name_map,
+    model_schema,
+    schema,
+)
 from pydantic.types import (
     DSN,
     UUID1,
@@ -1303,6 +1309,45 @@ def check_field(cls, v, *, values, config, field):
     }
 
 
+def test_unparameterized_schema_generation():
+    class FooList(BaseModel):
+        d: List
+
+    class BarList(BaseModel):
+        d: list
+
+    assert model_schema(FooList) == {
+        'title': 'FooList',
+        'type': 'object',
+        'properties': {'d': {'items': {}, 'title': 'D', 'type': 'array'}},
+        'required': ['d'],
+    }
+
+    foo_list_schema = model_schema(FooList)
+    bar_list_schema = model_schema(BarList)
+    bar_list_schema['title'] = 'FooList'  # to check for equality
+    assert foo_list_schema == bar_list_schema
+
+    class FooDict(BaseModel):
+        d: Dict
+
+    class BarDict(BaseModel):
+        d: dict
+
+    model_schema(Foo)
+    assert model_schema(FooDict) == {
+        'title': 'FooDict',
+        'type': 'object',
+        'properties': {'d': {'title': 'D', 'type': 'object'}},
+        'required': ['d'],
+    }
+
+    foo_dict_schema = model_schema(FooDict)
+    bar_dict_schema = model_schema(BarDict)
+    bar_dict_schema['title'] = 'FooDict'  # to check for equality
+    assert foo_dict_schema == bar_dict_schema
+
+
 def test_known_model_optimization():
     class Dep(BaseModel):
         number: int

Possible to give a more useful error message on partial type?
# Feature Request

Is it possible to give a more useful error message on partial type?

I think my code here is incorrect because I've not specified the parameters to `typing.Dict`, but would it be possible for this to give a more useful error message than "TypeError: issubclass() arg 1 must be a class"?

```py
from typing import Any, Dict

import pydantic
from pydantic.schema import model_schema

class Foo(pydantic.BaseModel):
  d: Dict
  # should be
  # d: Dict[Any, Any]
  
model_schema(Foo)
```
```
TypeError: issubclass() arg 1 must be a class
```
Possible to give a more useful error message on partial type?
# Feature Request

Is it possible to give a more useful error message on partial type?

I think my code here is incorrect because I've not specified the parameters to `typing.Dict`, but would it be possible for this to give a more useful error message than "TypeError: issubclass() arg 1 must be a class"?

```py
from typing import Any, Dict

import pydantic
from pydantic.schema import model_schema

class Foo(pydantic.BaseModel):
  d: Dict
  # should be
  # d: Dict[Any, Any]
  
model_schema(Foo)
```
```
TypeError: issubclass() arg 1 must be a class
```

tests/test_schema.py::test_unparameterized_schema_generation
tests/test_schema.py::test_key tests/test_schema.py::test_by_alias tests/test_schema.py::test_sub_model tests/test_schema.py::test_schema_class tests/test_schema.py::test_schema_repr tests/test_schema.py::test_schema_class_by_alias tests/test_schema.py::test_choices tests/test_schema.py::test_json_schema tests/test_schema.py::test_list_sub_model tests/test_schema.py::test_optional tests/test_schema.py::test_any tests/test_schema.py::test_set tests/test_schema.py::test_const_str tests/test_schema.py::test_const_false tests/test_schema.py::test_tuple[tuple-expected_schema0] tests/test_schema.py::test_tuple[field_type1-expected_schema1] tests/test_schema.py::test_tuple[field_type2-expected_schema2] tests/test_schema.py::test_bool tests/test_schema.py::test_strict_bool tests/test_schema.py::test_dict tests/test_schema.py::test_list tests/test_schema.py::test_list_union_dict[field_type0-expected_schema0] tests/test_schema.py::test_list_union_dict[field_type1-expected_schema1] tests/test_schema.py::test_list_union_dict[field_type2-expected_schema2] tests/test_schema.py::test_list_union_dict[field_type3-expected_schema3] tests/test_schema.py::test_list_union_dict[field_type4-expected_schema4] tests/test_schema.py::test_date_types[datetime-expected_schema0] tests/test_schema.py::test_date_types[date-expected_schema1] tests/test_schema.py::test_date_types[time-expected_schema2] tests/test_schema.py::test_date_types[timedelta-expected_schema3] tests/test_schema.py::test_str_basic_types[field_type0-expected_schema0] tests/test_schema.py::test_str_basic_types[field_type1-expected_schema1] tests/test_schema.py::test_str_basic_types[field_type2-expected_schema2] tests/test_schema.py::test_str_basic_types[field_type3-expected_schema3] tests/test_schema.py::test_str_constrained_types[StrictStr-expected_schema0] tests/test_schema.py::test_str_constrained_types[ConstrainedStr-expected_schema1] tests/test_schema.py::test_str_constrained_types[ConstrainedStrValue-expected_schema2] tests/test_schema.py::test_special_str_types[UrlStr-expected_schema0] tests/test_schema.py::test_special_str_types[UrlStrValue-expected_schema1] tests/test_schema.py::test_special_str_types[DSN-expected_schema2] tests/test_schema.py::test_email_str_types[EmailStr-email] tests/test_schema.py::test_email_str_types[NameEmail-name-email] tests/test_schema.py::test_secret_types[SecretBytes-string] tests/test_schema.py::test_secret_types[SecretStr-string] tests/test_schema.py::test_special_int_types[ConstrainedInt-expected_schema0] tests/test_schema.py::test_special_int_types[ConstrainedIntValue-expected_schema1] tests/test_schema.py::test_special_int_types[ConstrainedIntValue-expected_schema2] tests/test_schema.py::test_special_int_types[ConstrainedIntValue-expected_schema3] tests/test_schema.py::test_special_int_types[PositiveInt-expected_schema4] tests/test_schema.py::test_special_int_types[NegativeInt-expected_schema5] tests/test_schema.py::test_special_float_types[ConstrainedFloat-expected_schema0] tests/test_schema.py::test_special_float_types[ConstrainedFloatValue-expected_schema1] tests/test_schema.py::test_special_float_types[ConstrainedFloatValue-expected_schema2] tests/test_schema.py::test_special_float_types[ConstrainedFloatValue-expected_schema3] tests/test_schema.py::test_special_float_types[PositiveFloat-expected_schema4] tests/test_schema.py::test_special_float_types[NegativeFloat-expected_schema5] tests/test_schema.py::test_special_float_types[ConstrainedDecimal-expected_schema6] tests/test_schema.py::test_special_float_types[ConstrainedDecimalValue-expected_schema7] tests/test_schema.py::test_special_float_types[ConstrainedDecimalValue-expected_schema8] tests/test_schema.py::test_special_float_types[ConstrainedDecimalValue-expected_schema9] tests/test_schema.py::test_uuid_types[UUID-uuid] tests/test_schema.py::test_uuid_types[UUID1-uuid1] tests/test_schema.py::test_uuid_types[UUID3-uuid3] tests/test_schema.py::test_uuid_types[UUID4-uuid4] tests/test_schema.py::test_uuid_types[UUID5-uuid5] tests/test_schema.py::test_path_types[FilePath-file-path] tests/test_schema.py::test_path_types[DirectoryPath-directory-path] tests/test_schema.py::test_path_types[Path-path] tests/test_schema.py::test_json_type tests/test_schema.py::test_ipv4address_type tests/test_schema.py::test_ipv6address_type tests/test_schema.py::test_ipvanyaddress_type tests/test_schema.py::test_ipv4interface_type tests/test_schema.py::test_ipv6interface_type tests/test_schema.py::test_ipvanyinterface_type tests/test_schema.py::test_ipv4network_type tests/test_schema.py::test_ipv6network_type tests/test_schema.py::test_ipvanynetwork_type tests/test_schema.py::test_callable_type[annotation0] tests/test_schema.py::test_callable_type[annotation1] tests/test_schema.py::test_error_non_supported_types tests/test_schema.py::test_flat_models_unique_models tests/test_schema.py::test_flat_models_with_submodels tests/test_schema.py::test_flat_models_with_submodels_from_sequence tests/test_schema.py::test_model_name_maps tests/test_schema.py::test_schema_overrides tests/test_schema.py::test_schema_from_models tests/test_schema.py::test_schema_with_ref_prefix tests/test_schema.py::test_schema_no_definitions tests/test_schema.py::test_list_default tests/test_schema.py::test_dict_default tests/test_schema.py::test_constraints_schema[kwargs0-str-expected_extra0] tests/test_schema.py::test_constraints_schema[kwargs1-ConstrainedStrValue-expected_extra1] tests/test_schema.py::test_constraints_schema[kwargs2-str-expected_extra2] tests/test_schema.py::test_constraints_schema[kwargs3-bytes-expected_extra3] tests/test_schema.py::test_constraints_schema[kwargs4-str-expected_extra4] tests/test_schema.py::test_constraints_schema[kwargs5-int-expected_extra5] tests/test_schema.py::test_constraints_schema[kwargs6-int-expected_extra6] tests/test_schema.py::test_constraints_schema[kwargs7-int-expected_extra7] tests/test_schema.py::test_constraints_schema[kwargs8-int-expected_extra8] tests/test_schema.py::test_constraints_schema[kwargs9-int-expected_extra9] tests/test_schema.py::test_constraints_schema[kwargs10-float-expected_extra10] tests/test_schema.py::test_constraints_schema[kwargs11-float-expected_extra11] tests/test_schema.py::test_constraints_schema[kwargs12-float-expected_extra12] tests/test_schema.py::test_constraints_schema[kwargs13-float-expected_extra13] tests/test_schema.py::test_constraints_schema[kwargs14-float-expected_extra14] tests/test_schema.py::test_constraints_schema[kwargs15-Decimal-expected_extra15] tests/test_schema.py::test_constraints_schema[kwargs16-Decimal-expected_extra16] tests/test_schema.py::test_constraints_schema[kwargs17-Decimal-expected_extra17] tests/test_schema.py::test_constraints_schema[kwargs18-Decimal-expected_extra18] tests/test_schema.py::test_constraints_schema[kwargs19-Decimal-expected_extra19] tests/test_schema.py::test_not_constraints_schema[kwargs0-int-expected0] tests/test_schema.py::test_not_constraints_schema[kwargs1-float-expected1] tests/test_schema.py::test_not_constraints_schema[kwargs2-Decimal-expected2] tests/test_schema.py::test_not_constraints_schema[kwargs3-int-expected3] tests/test_schema.py::test_not_constraints_schema[kwargs4-str-expected4] tests/test_schema.py::test_not_constraints_schema[kwargs5-bytes-expected5] tests/test_schema.py::test_not_constraints_schema[kwargs6-str-expected6] tests/test_schema.py::test_not_constraints_schema[kwargs7-bool-expected7] tests/test_schema.py::test_constraints_schema_validation[kwargs0-str-foo] tests/test_schema.py::test_constraints_schema_validation[kwargs1-ConstrainedStrValue-foo] tests/test_schema.py::test_constraints_schema_validation[kwargs2-str-foo] tests/test_schema.py::test_constraints_schema_validation[kwargs3-bytes-foo] tests/test_schema.py::test_constraints_schema_validation[kwargs4-str-foo] tests/test_schema.py::test_constraints_schema_validation[kwargs5-bool-True] tests/test_schema.py::test_constraints_schema_validation[kwargs6-int-3] tests/test_schema.py::test_constraints_schema_validation[kwargs7-int-3] tests/test_schema.py::test_constraints_schema_validation[kwargs8-int-3] tests/test_schema.py::test_constraints_schema_validation[kwargs9-int-2] tests/test_schema.py::test_constraints_schema_validation[kwargs10-int-3] tests/test_schema.py::test_constraints_schema_validation[kwargs11-int-3] tests/test_schema.py::test_constraints_schema_validation[kwargs12-int-5] tests/test_schema.py::test_constraints_schema_validation[kwargs13-float-3.0] tests/test_schema.py::test_constraints_schema_validation[kwargs14-float-2.1] tests/test_schema.py::test_constraints_schema_validation[kwargs15-float-3.0] tests/test_schema.py::test_constraints_schema_validation[kwargs16-float-4.9] tests/test_schema.py::test_constraints_schema_validation[kwargs17-float-3.0] tests/test_schema.py::test_constraints_schema_validation[kwargs18-float-2.0] tests/test_schema.py::test_constraints_schema_validation[kwargs19-float-3.0] tests/test_schema.py::test_constraints_schema_validation[kwargs20-float-5.0] tests/test_schema.py::test_constraints_schema_validation[kwargs21-float-3] tests/test_schema.py::test_constraints_schema_validation[kwargs22-float-3] tests/test_schema.py::test_constraints_schema_validation[kwargs23-Decimal-value23] tests/test_schema.py::test_constraints_schema_validation[kwargs24-Decimal-value24] tests/test_schema.py::test_constraints_schema_validation[kwargs25-Decimal-value25] tests/test_schema.py::test_constraints_schema_validation[kwargs26-Decimal-value26] tests/test_schema.py::test_constraints_schema_validation[kwargs27-Decimal-value27] tests/test_schema.py::test_constraints_schema_validation[kwargs28-Decimal-value28] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs0-str-foobar] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs1-str-f] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs2-str-bar] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs3-int-2] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs4-int-5] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs5-int-1] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs6-int-6] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs7-float-2.0] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs8-float-5.0] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs9-float-1.9] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs10-float-5.1] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs11-Decimal-value11] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs12-Decimal-value12] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs13-Decimal-value13] tests/test_schema.py::test_constraints_schema_validation_raises[kwargs14-Decimal-value14] tests/test_schema.py::test_schema_kwargs tests/test_schema.py::test_schema_dict_constr tests/test_schema.py::test_bytes_constrained_types[ConstrainedBytes-expected_schema0] tests/test_schema.py::test_bytes_constrained_types[ConstrainedBytesValue-expected_schema1] tests/test_schema.py::test_optional_dict tests/test_schema.py::test_field_with_validator tests/test_schema.py::test_known_model_optimization