Fix crash on datafields

Fixes the crash reported at pylint-dev/pylint#4963
Tests added there.

ChangeLog

@@ -20,6 +20,9 @@ What's New in astroid 2.7.4?
 ============================
 Release date: TBA
 
+* Fixed bug in inference of dataclass field calls.
+
+    Closes PyCQA/pylint#4963
 
 
 What's New in astroid 2.7.3?

astroid/brain/brain_dataclasses.py

@@ -16,6 +16,7 @@
 from astroid.manager import AstroidManager
 from astroid.nodes.node_classes import (
     AnnAssign,
+    Assign,
     AssignName,
     Attribute,
     Call,
@@ -231,19 +232,20 @@ def infer_dataclass_attribute(
 
 
 def infer_dataclass_field_call(
-    node: AssignName, ctx: context.InferenceContext = None
+    node: Call, ctx: context.InferenceContext = None
 ) -> Generator:
     """Inference tip for dataclass field calls."""
-    field_call = node.parent.value
-    default_type, default = _get_field_default(field_call)
-    if not default_type:
-        yield Uninferable
-    elif default_type == "default":
-        yield from default.infer(context=ctx)
-    else:
-        new_call = parse(default.as_string()).body[0].value
-        new_call.parent = field_call.parent
-        yield from new_call.infer(context=ctx)
+    if isinstance(node.parent, (AnnAssign, Assign)):
+        field_call = node.parent.value
+        default_type, default = _get_field_default(field_call)
+        if not default_type:
+            yield Uninferable
+        elif default_type == "default":
+            yield from default.infer(context=ctx)
+        else:
+            new_call = parse(default.as_string()).body[0].value
+            new_call.parent = field_call.parent
+            yield from new_call.infer(context=ctx)
 
 
 def _looks_like_dataclass_decorator(