[mypyc] Compile away NewType type calls (#14398)

For example, here the call to ID is simply a no-op at runtime, returning
1 unchanged.

    ID = NewType('ID', int)
    person = ID(1)

Resolves mypyc/mypyc#958

mypyc/irbuild/expression.py

@@ -266,13 +266,20 @@ def transform_super_expr(builder: IRBuilder, o: SuperExpr) -> Value:
 
 
 def transform_call_expr(builder: IRBuilder, expr: CallExpr) -> Value:
+    callee = expr.callee
     if isinstance(expr.analyzed, CastExpr):
         return translate_cast_expr(builder, expr.analyzed)
     elif isinstance(expr.analyzed, AssertTypeExpr):
         # Compile to a no-op.
         return builder.accept(expr.analyzed.expr)
+    elif (
+        isinstance(callee, (NameExpr, MemberExpr))
+        and isinstance(callee.node, TypeInfo)
+        and callee.node.is_newtype
+    ):
+        # A call to a NewType type is a no-op at runtime.
+        return builder.accept(expr.args[0])
 
-    callee = expr.callee
     if isinstance(callee, IndexExpr) and isinstance(callee.analyzed, TypeApplication):
         callee = callee.analyzed.expr  # Unwrap type application
 

mypyc/test-data/irbuild-basic.test

@@ -2338,11 +2338,8 @@ def __top_level__():
     r92, r93, r94, r95 :: ptr
     r96 :: dict
     r97 :: str
-    r98, r99 :: object
-    r100 :: dict
-    r101 :: str
-    r102 :: int32
-    r103 :: bit
+    r98 :: int32
+    r99 :: bit
 L0:
     r0 = builtins :: module
     r1 = load_address _Py_NoneStruct
@@ -2454,13 +2451,9 @@ L2:
     set_mem r95, r91 :: builtins.object*
     keep_alive r88
     r96 = __main__.globals :: static
-    r97 = 'Bar'
-    r98 = CPyDict_GetItem(r96, r97)
-    r99 = PyObject_CallFunctionObjArgs(r98, r88, 0)
-    r100 = __main__.globals :: static
-    r101 = 'y'
-    r102 = CPyDict_SetItem(r100, r101, r99)
-    r103 = r102 >= 0 :: signed
+    r97 = 'y'
+    r98 = CPyDict_SetItem(r96, r97, r88)
+    r99 = r98 >= 0 :: signed
     return 1
 
 [case testChainedConditional]
@@ -3584,3 +3577,18 @@ L0:
     r3 = 0.0
     i__redef____redef__ = r3
     return 1
+
+[case testNewType]
+from typing import NewType
+
+class A: pass
+
+N = NewType("N", A)
+
+def f(arg: A) -> N:
+    return N(arg)
+[out]
+def f(arg):
+    arg :: __main__.A
+L0:
+    return arg