Revert constraint deduplication

Author: sterliakov

mypy/constraints.py

@@ -251,7 +251,6 @@ def infer_constraints_for_callable(
                     )
                     c = infer_constraints(callee.arg_types[i], actual_type, SUPERTYPE_OF)
                     constraints.extend(c)
-
     if (
         param_spec
         and not any(c.type_var == param_spec.id for c in constraints)
@@ -271,8 +270,6 @@ def infer_constraints_for_callable(
                 ),
             )
         )
-
-    constraints = list(dict.fromkeys(constraints))
     if any(isinstance(v, ParamSpecType) for v in callee.variables):
         # As a perf optimization filter imprecise constraints only when we can have them.
         constraints = filter_imprecise_kinds(constraints)

test-data/unit/check-typeddict.test

@@ -1164,21 +1164,22 @@ fc(b) # E: Argument 1 to "fc" has incompatible type "B"; expected "C"
 from typing import TypedDict, TypeVar
 A = TypedDict('A', {'x': int})
 B = TypedDict('B', {'x': int}, total=False)
-B2 = TypedDict('B2', {'x': int}, total=False)
 C = TypedDict('C', {'x': int, 'y': str}, total=False)
-C2 = TypedDict('C2', {'x': int, 'y': str}, total=False)
 T = TypeVar('T')
 def j(x: T, y: T) -> T: return x
 a: A
 b: B
-b2: B2
 c: C
-c2: C2
-reveal_type(j(a, b)) # N: Revealed type is "TypedDict({})"
-reveal_type(j(b, b2)) # N: Revealed type is "TypedDict({'x'?: builtins.int})"
-reveal_type(j(c, c2)) # N: Revealed type is "TypedDict({'x'?: builtins.int, 'y'?: builtins.str})"
-reveal_type(j(b, c)) # N: Revealed type is "TypedDict({'x'?: builtins.int})"
-reveal_type(j(c, b)) # N: Revealed type is "TypedDict({'x'?: builtins.int})"
+reveal_type(j(a, b)) \
+    # N: Revealed type is "TypedDict({})"
+reveal_type(j(b, b)) \
+    # N: Revealed type is "TypedDict({'x'?: builtins.int})"
+reveal_type(j(c, c)) \
+    # N: Revealed type is "TypedDict({'x'?: builtins.int, 'y'?: builtins.str})"
+reveal_type(j(b, c)) \
+    # N: Revealed type is "TypedDict({'x'?: builtins.int})"
+reveal_type(j(c, b)) \
+    # N: Revealed type is "TypedDict({'x'?: builtins.int})"
 [builtins fixtures/dict.pyi]
 [typing fixtures/typing-typeddict.pyi]