Lib/test/test_compile.py

import dis
import math
import os
import unittest
import sys
import _ast
import tempfile
import types
from test import support
from test.support import script_helper, FakePath

class TestSpecifics(unittest.TestCase):

    def compile_single(self, source):
        compile(source, "<single>", "single")

    def assertInvalidSingle(self, source):
        self.assertRaises(SyntaxError, self.compile_single, source)

    def test_no_ending_newline(self):
        compile("hi", "<test>", "exec")
        compile("hi\r", "<test>", "exec")

    def test_empty(self):
        compile("", "<test>", "exec")

    def test_other_newlines(self):
        compile("\r\n", "<test>", "exec")
        compile("\r", "<test>", "exec")
        compile("hi\r\nstuff\r\ndef f():\n    pass\r", "<test>", "exec")
        compile("this_is\rreally_old_mac\rdef f():\n    pass", "<test>", "exec")

    def test_debug_assignment(self):
        # catch assignments to __debug__
        self.assertRaises(SyntaxError, compile, '__debug__ = 1', '?', 'single')
        import builtins
        prev = builtins.__debug__
        setattr(builtins, '__debug__', 'sure')
        self.assertEqual(__debug__, prev)
        setattr(builtins, '__debug__', prev)

    def test_argument_handling(self):
        # detect duplicate positional and keyword arguments
        self.assertRaises(SyntaxError, eval, 'lambda a,a:0')
        self.assertRaises(SyntaxError, eval, 'lambda a,a=1:0')
        self.assertRaises(SyntaxError, eval, 'lambda a=1,a=1:0')
        self.assertRaises(SyntaxError, exec, 'def f(a, a): pass')
        self.assertRaises(SyntaxError, exec, 'def f(a = 0, a = 1): pass')
        self.assertRaises(SyntaxError, exec, 'def f(a): global a; a = 1')

    def test_syntax_error(self):
        self.assertRaises(SyntaxError, compile, "1+*3", "filename", "exec")

    def test_none_keyword_arg(self):
        self.assertRaises(SyntaxError, compile, "f(None=1)", "<string>", "exec")

    def test_duplicate_global_local(self):
        self.assertRaises(SyntaxError, exec, 'def f(a): global a; a = 1')

    def test_exec_with_general_mapping_for_locals(self):

        class M:
            "Test mapping interface versus possible calls from eval()."
            def __getitem__(self, key):
                if key == 'a':
                    return 12
                raise KeyError
            def __setitem__(self, key, value):
                self.results = (key, value)
            def keys(self):
                return list('xyz')

        m = M()
        g = globals()
        exec('z = a', g, m)
        self.assertEqual(m.results, ('z', 12))
        try:
            exec('z = b', g, m)
        except NameError:
            pass
        else:
            self.fail('Did not detect a KeyError')
        exec('z = dir()', g, m)
        self.assertEqual(m.results, ('z', list('xyz')))
        exec('z = globals()', g, m)
        self.assertEqual(m.results, ('z', g))
        exec('z = locals()', g, m)
        self.assertEqual(m.results, ('z', m))
        self.assertRaises(TypeError, exec, 'z = b', m)

        class A:
            "Non-mapping"
            pass
        m = A()
        self.assertRaises(TypeError, exec, 'z = a', g, m)

        # Verify that dict subclasses work as well
        class D(dict):
            def __getitem__(self, key):
                if key == 'a':
                    return 12
                return dict.__getitem__(self, key)
        d = D()
        exec('z = a', g, d)
        self.assertEqual(d['z'], 12)

    def test_extended_arg(self):
        longexpr = 'x = x or ' + '-x' * 2500
        g = {}
        code = '''
def f(x):
    %s
    %s
    %s
    %s
    %s
    %s
    %s
    %s
    %s
    %s
    # the expressions above have no effect, x == argument
    while x:
        x -= 1
        # EXTENDED_ARG/JUMP_ABSOLUTE here
    return x
''' % ((longexpr,)*10)
        exec(code, g)
        self.assertEqual(g['f'](5), 0)

    def test_argument_order(self):
        self.assertRaises(SyntaxError, exec, 'def f(a=1, b): pass')

    def test_float_literals(self):
        # testing bad float literals
        self.assertRaises(SyntaxError, eval, "2e")
        self.assertRaises(SyntaxError, eval, "2.0e+")
        self.assertRaises(SyntaxError, eval, "1e-")
        self.assertRaises(SyntaxError, eval, "3-4e/21")

    def test_indentation(self):
        # testing compile() of indented block w/o trailing newline"
        s = """
if 1:
    if 2:
        pass"""
        compile(s, "<string>", "exec")

    # This test is probably specific to CPython and may not generalize
    # to other implementations.  We are trying to ensure that when
    # the first line of code starts after 256, correct line numbers
    # in tracebacks are still produced.
    def test_leading_newlines(self):
        s256 = "".join(["\n"] * 256 + ["spam"])
        co = compile(s256, 'fn', 'exec')
        self.assertEqual(co.co_firstlineno, 257)
        self.assertEqual(co.co_lnotab, bytes())

    def test_literals_with_leading_zeroes(self):
        for arg in ["077787", "0xj", "0x.", "0e",  "090000000000000",
                    "080000000000000", "000000000000009", "000000000000008",
                    "0b42", "0BADCAFE", "0o123456789", "0b1.1", "0o4.2",
                    "0b101j2", "0o153j2", "0b100e1", "0o777e1", "0777",
                    "000777", "000000000000007"]:
            self.assertRaises(SyntaxError, eval, arg)

        self.assertEqual(eval("0xff"), 255)
        self.assertEqual(eval("0777."), 777)
        self.assertEqual(eval("0777.0"), 777)
        self.assertEqual(eval("000000000000000000000000000000000000000000000000000777e0"), 777)
        self.assertEqual(eval("0777e1"), 7770)
        self.assertEqual(eval("0e0"), 0)
        self.assertEqual(eval("0000e-012"), 0)
        self.assertEqual(eval("09.5"), 9.5)
        self.assertEqual(eval("0777j"), 777j)
        self.assertEqual(eval("000"), 0)
        self.assertEqual(eval("00j"), 0j)
        self.assertEqual(eval("00.0"), 0)
        self.assertEqual(eval("0e3"), 0)
        self.assertEqual(eval("090000000000000."), 90000000000000.)
        self.assertEqual(eval("090000000000000.0000000000000000000000"), 90000000000000.)
        self.assertEqual(eval("090000000000000e0"), 90000000000000.)
        self.assertEqual(eval("090000000000000e-0"), 90000000000000.)
        self.assertEqual(eval("090000000000000j"), 90000000000000j)
        self.assertEqual(eval("000000000000008."), 8.)
        self.assertEqual(eval("000000000000009."), 9.)
        self.assertEqual(eval("0b101010"), 42)
        self.assertEqual(eval("-0b000000000010"), -2)
        self.assertEqual(eval("0o777"), 511)
        self.assertEqual(eval("-0o0000010"), -8)

    def test_unary_minus(self):
        # Verify treatment of unary minus on negative numbers SF bug #660455
        if sys.maxsize == 2147483647:
            # 32-bit machine
            all_one_bits = '0xffffffff'
            self.assertEqual(eval(all_one_bits), 4294967295)
            self.assertEqual(eval("-" + all_one_bits), -4294967295)
        elif sys.maxsize == 9223372036854775807:
            # 64-bit machine
            all_one_bits = '0xffffffffffffffff'
            self.assertEqual(eval(all_one_bits), 18446744073709551615)
            self.assertEqual(eval("-" + all_one_bits), -18446744073709551615)
        else:
            self.fail("How many bits *does* this machine have???")
        # Verify treatment of constant folding on -(sys.maxsize+1)
        # i.e. -2147483648 on 32 bit platforms.  Should return int.
        self.assertIsInstance(eval("%s" % (-sys.maxsize - 1)), int)
        self.assertIsInstance(eval("%s" % (-sys.maxsize - 2)), int)

    if sys.maxsize == 9223372036854775807:
        def test_32_63_bit_values(self):
            a = +4294967296  # 1 << 32
            b = -4294967296  # 1 << 32
            c = +281474976710656  # 1 << 48
            d = -281474976710656  # 1 << 48
            e = +4611686018427387904  # 1 << 62
            f = -4611686018427387904  # 1 << 62
            g = +9223372036854775807  # 1 << 63 - 1
            h = -9223372036854775807  # 1 << 63 - 1

            for variable in self.test_32_63_bit_values.__code__.co_consts:
                if variable is not None:
                    self.assertIsInstance(variable, int)

    def test_sequence_unpacking_error(self):
        # Verify sequence packing/unpacking with "or".  SF bug #757818
        i,j = (1, -1) or (-1, 1)
        self.assertEqual(i, 1)
        self.assertEqual(j, -1)

    def test_none_assignment(self):
        stmts = [
            'None = 0',
            'None += 0',
            '__builtins__.None = 0',
            'def None(): pass',
            'class None: pass',
            '(a, None) = 0, 0',
            'for None in range(10): pass',
            'def f(None): pass',
            'import None',
            'import x as None',
            'from x import None',
            'from x import y as None'
        ]
        for stmt in stmts:
            stmt += "\n"
            self.assertRaises(SyntaxError, compile, stmt, 'tmp', 'single')
            self.assertRaises(SyntaxError, compile, stmt, 'tmp', 'exec')

    def test_import(self):
        succeed = [
            'import sys',
            'import os, sys',
            'import os as bar',
            'import os.path as bar',
            'from __future__ import nested_scopes, generators',
            'from __future__ import (nested_scopes,\ngenerators)',
            'from __future__ import (nested_scopes,\ngenerators,)',
            'from sys import stdin, stderr, stdout',
            'from sys import (stdin, stderr,\nstdout)',
            'from sys import (stdin, stderr,\nstdout,)',
            'from sys import (stdin\n, stderr, stdout)',
            'from sys import (stdin\n, stderr, stdout,)',
            'from sys import stdin as si, stdout as so, stderr as se',
            'from sys import (stdin as si, stdout as so, stderr as se)',
            'from sys import (stdin as si, stdout as so, stderr as se,)',
            ]
        fail = [
            'import (os, sys)',
            'import (os), (sys)',
            'import ((os), (sys))',
            'import (sys',
            'import sys)',
            'import (os,)',
            'import os As bar',
            'import os.path a bar',
            'from sys import stdin As stdout',
            'from sys import stdin a stdout',
            'from (sys) import stdin',
            'from __future__ import (nested_scopes',
            'from __future__ import nested_scopes)',
            'from __future__ import nested_scopes,\ngenerators',
            'from sys import (stdin',
            'from sys import stdin)',
            'from sys import stdin, stdout,\nstderr',
            'from sys import stdin si',
            'from sys import stdin,',
            'from sys import (*)',
            'from sys import (stdin,, stdout, stderr)',
            'from sys import (stdin, stdout),',
            ]
        for stmt in succeed:
            compile(stmt, 'tmp', 'exec')
        for stmt in fail:
            self.assertRaises(SyntaxError, compile, stmt, 'tmp', 'exec')

    def test_for_distinct_code_objects(self):
        # SF bug 1048870
        def f():
            f1 = lambda x=1: x
            f2 = lambda x=2: x
            return f1, f2
        f1, f2 = f()
        self.assertNotEqual(id(f1.__code__), id(f2.__code__))

    def test_lambda_doc(self):
        l = lambda: "foo"
        self.assertIsNone(l.__doc__)

    def test_encoding(self):
        code = b'# -*- coding: badencoding -*-\npass\n'
        self.assertRaises(SyntaxError, compile, code, 'tmp', 'exec')
        code = '# -*- coding: badencoding -*-\n"\xc2\xa4"\n'
        compile(code, 'tmp', 'exec')
        self.assertEqual(eval(code), '\xc2\xa4')
        code = '"\xc2\xa4"\n'
        self.assertEqual(eval(code), '\xc2\xa4')
        code = b'"\xc2\xa4"\n'
        self.assertEqual(eval(code), '\xa4')
        code = b'# -*- coding: latin1 -*-\n"\xc2\xa4"\n'
        self.assertEqual(eval(code), '\xc2\xa4')
        code = b'# -*- coding: utf-8 -*-\n"\xc2\xa4"\n'
        self.assertEqual(eval(code), '\xa4')
        code = b'# -*- coding: iso8859-15 -*-\n"\xc2\xa4"\n'
        self.assertEqual(eval(code), '\xc2\u20ac')
        code = '"""\\\n# -*- coding: iso8859-15 -*-\n\xc2\xa4"""\n'
        self.assertEqual(eval(code), '# -*- coding: iso8859-15 -*-\n\xc2\xa4')
        code = b'"""\\\n# -*- coding: iso8859-15 -*-\n\xc2\xa4"""\n'
        self.assertEqual(eval(code), '# -*- coding: iso8859-15 -*-\n\xa4')

    def test_subscripts(self):
        # SF bug 1448804
        # Class to make testing subscript results easy
        class str_map(object):
            def __init__(self):
                self.data = {}
            def __getitem__(self, key):
                return self.data[str(key)]
            def __setitem__(self, key, value):
                self.data[str(key)] = value
            def __delitem__(self, key):
                del self.data[str(key)]
            def __contains__(self, key):
                return str(key) in self.data
        d = str_map()
        # Index
        d[1] = 1
        self.assertEqual(d[1], 1)
        d[1] += 1
        self.assertEqual(d[1], 2)
        del d[1]
        self.assertNotIn(1, d)
        # Tuple of indices
        d[1, 1] = 1
        self.assertEqual(d[1, 1], 1)
        d[1, 1] += 1
        self.assertEqual(d[1, 1], 2)
        del d[1, 1]
        self.assertNotIn((1, 1), d)
        # Simple slice
        d[1:2] = 1
        self.assertEqual(d[1:2], 1)
        d[1:2] += 1
        self.assertEqual(d[1:2], 2)
        del d[1:2]
        self.assertNotIn(slice(1, 2), d)
        # Tuple of simple slices
        d[1:2, 1:2] = 1
        self.assertEqual(d[1:2, 1:2], 1)
        d[1:2, 1:2] += 1
        self.assertEqual(d[1:2, 1:2], 2)
        del d[1:2, 1:2]
        self.assertNotIn((slice(1, 2), slice(1, 2)), d)
        # Extended slice
        d[1:2:3] = 1
        self.assertEqual(d[1:2:3], 1)
        d[1:2:3] += 1
        self.assertEqual(d[1:2:3], 2)
        del d[1:2:3]
        self.assertNotIn(slice(1, 2, 3), d)
        # Tuple of extended slices
        d[1:2:3, 1:2:3] = 1
        self.assertEqual(d[1:2:3, 1:2:3], 1)
        d[1:2:3, 1:2:3] += 1
        self.assertEqual(d[1:2:3, 1:2:3], 2)
        del d[1:2:3, 1:2:3]
        self.assertNotIn((slice(1, 2, 3), slice(1, 2, 3)), d)
        # Ellipsis
        d[...] = 1
        self.assertEqual(d[...], 1)
        d[...] += 1
        self.assertEqual(d[...], 2)
        del d[...]
        self.assertNotIn(Ellipsis, d)
        # Tuple of Ellipses
        d[..., ...] = 1
        self.assertEqual(d[..., ...], 1)
        d[..., ...] += 1
        self.assertEqual(d[..., ...], 2)
        del d[..., ...]
        self.assertNotIn((Ellipsis, Ellipsis), d)

    def test_annotation_limit(self):
        # more than 255 annotations, should compile ok
        s = "def f(%s): pass"
        s %= ', '.join('a%d:%d' % (i,i) for i in range(300))
        compile(s, '?', 'exec')

    def test_mangling(self):
        class A:
            def f():
                __mangled = 1
                __not_mangled__ = 2
                import __mangled_mod
                import __package__.module

        self.assertIn("_A__mangled", A.f.__code__.co_varnames)
        self.assertIn("__not_mangled__", A.f.__code__.co_varnames)
        self.assertIn("_A__mangled_mod", A.f.__code__.co_varnames)
        self.assertIn("__package__", A.f.__code__.co_varnames)

    def test_compile_ast(self):
        fname = __file__
        if fname.lower().endswith('pyc'):
            fname = fname[:-1]
        with open(fname, 'r') as f:
            fcontents = f.read()
        sample_code = [
            ['<assign>', 'x = 5'],
            ['<ifblock>', """if True:\n    pass\n"""],
            ['<forblock>', """for n in [1, 2, 3]:\n    print(n)\n"""],
            ['<deffunc>', """def foo():\n    pass\nfoo()\n"""],
            [fname, fcontents],
        ]

        for fname, code in sample_code:
            co1 = compile(code, '%s1' % fname, 'exec')
            ast = compile(code, '%s2' % fname, 'exec', _ast.PyCF_ONLY_AST)
            self.assertTrue(type(ast) == _ast.Module)
            co2 = compile(ast, '%s3' % fname, 'exec')
            self.assertEqual(co1, co2)
            # the code object's filename comes from the second compilation step
            self.assertEqual(co2.co_filename, '%s3' % fname)

        # raise exception when node type doesn't match with compile mode
        co1 = compile('print(1)', '<string>', 'exec', _ast.PyCF_ONLY_AST)
        self.assertRaises(TypeError, compile, co1, '<ast>', 'eval')

        # raise exception when node type is no start node
        self.assertRaises(TypeError, compile, _ast.If(), '<ast>', 'exec')

        # raise exception when node has invalid children
        ast = _ast.Module()
        ast.body = [_ast.BoolOp()]
        self.assertRaises(TypeError, compile, ast, '<ast>', 'exec')

    def test_dict_evaluation_order(self):
        i = 0

        def f():
            nonlocal i
            i += 1
            return i

        d = {f(): f(), f(): f()}
        self.assertEqual(d, {1: 2, 3: 4})

    def test_compile_filename(self):
        for filename in 'file.py', b'file.py':
            code = compile('pass', filename, 'exec')
            self.assertEqual(code.co_filename, 'file.py')
        for filename in bytearray(b'file.py'), memoryview(b'file.py'):
            with self.assertWarns(DeprecationWarning):
                code = compile('pass', filename, 'exec')
            self.assertEqual(code.co_filename, 'file.py')
        self.assertRaises(TypeError, compile, 'pass', list(b'file.py'), 'exec')

    @support.cpython_only
    def test_same_filename_used(self):
        s = """def f(): pass\ndef g(): pass"""
        c = compile(s, "myfile", "exec")
        for obj in c.co_consts:
            if isinstance(obj, types.CodeType):
                self.assertIs(obj.co_filename, c.co_filename)

    def test_single_statement(self):
        self.compile_single("1 + 2")
        self.compile_single("\n1 + 2")
        self.compile_single("1 + 2\n")
        self.compile_single("1 + 2\n\n")
        self.compile_single("1 + 2\t\t\n")
        self.compile_single("1 + 2\t\t\n        ")
        self.compile_single("1 + 2 # one plus two")
        self.compile_single("1; 2")
        self.compile_single("import sys; sys")
        self.compile_single("def f():\n   pass")
        self.compile_single("while False:\n   pass")
        self.compile_single("if x:\n   f(x)")
        self.compile_single("if x:\n   f(x)\nelse:\n   g(x)")
        self.compile_single("class T:\n   pass")

    def test_bad_single_statement(self):
        self.assertInvalidSingle('1\n2')
        self.assertInvalidSingle('def f(): pass')
        self.assertInvalidSingle('a = 13\nb = 187')
        self.assertInvalidSingle('del x\ndel y')
        self.assertInvalidSingle('f()\ng()')
        self.assertInvalidSingle('f()\n# blah\nblah()')
        self.assertInvalidSingle('f()\nxy # blah\nblah()')
        self.assertInvalidSingle('x = 5 # comment\nx = 6\n')

    def test_particularly_evil_undecodable(self):
        # Issue 24022
        src = b'0000\x00\n00000000000\n\x00\n\x9e\n'
        with tempfile.TemporaryDirectory() as tmpd:
            fn = os.path.join(tmpd, "bad.py")
            with open(fn, "wb") as fp:
                fp.write(src)
            res = script_helper.run_python_until_end(fn)[0]
        self.assertIn(b"Non-UTF-8", res.err)

    def test_yet_more_evil_still_undecodable(self):
        # Issue #25388
        src = b"#\x00\n#\xfd\n"
        with tempfile.TemporaryDirectory() as tmpd:
            fn = os.path.join(tmpd, "bad.py")
            with open(fn, "wb") as fp:
                fp.write(src)
            res = script_helper.run_python_until_end(fn)[0]
        self.assertIn(b"Non-UTF-8", res.err)

    @support.cpython_only
    def test_compiler_recursion_limit(self):
        # Expected limit is sys.getrecursionlimit() * the scaling factor
        # in symtable.c (currently 3)
        # We expect to fail *at* that limit, because we use up some of
        # the stack depth limit in the test suite code
        # So we check the expected limit and 75% of that
        # XXX (ncoghlan): duplicating the scaling factor here is a little
        # ugly. Perhaps it should be exposed somewhere...
        fail_depth = sys.getrecursionlimit() * 3
        success_depth = int(fail_depth * 0.75)

        def check_limit(prefix, repeated):
            expect_ok = prefix + repeated * success_depth
            self.compile_single(expect_ok)
            broken = prefix + repeated * fail_depth
            details = "Compiling ({!r} + {!r} * {})".format(
                         prefix, repeated, fail_depth)
            with self.assertRaises(RecursionError, msg=details):
                self.compile_single(broken)

        check_limit("a", "()")
        check_limit("a", ".b")
        check_limit("a", "[0]")
        check_limit("a", "*a")

    def test_null_terminated(self):
        # The source code is null-terminated internally, but bytes-like
        # objects are accepted, which could be not terminated.
        with self.assertRaisesRegex(ValueError, "cannot contain null"):
            compile("123\x00", "<dummy>", "eval")
        with self.assertRaisesRegex(ValueError, "cannot contain null"):
            compile(memoryview(b"123\x00"), "<dummy>", "eval")
        code = compile(memoryview(b"123\x00")[1:-1], "<dummy>", "eval")
        self.assertEqual(eval(code), 23)
        code = compile(memoryview(b"1234")[1:-1], "<dummy>", "eval")
        self.assertEqual(eval(code), 23)
        code = compile(memoryview(b"$23$")[1:-1], "<dummy>", "eval")
        self.assertEqual(eval(code), 23)

        # Also test when eval() and exec() do the compilation step
        self.assertEqual(eval(memoryview(b"1234")[1:-1]), 23)
        namespace = dict()
        exec(memoryview(b"ax = 123")[1:-1], namespace)
        self.assertEqual(namespace['x'], 12)

    def check_constant(self, func, expected):
        for const in func.__code__.co_consts:
            if repr(const) == repr(expected):
                break
        else:
            self.fail("unable to find constant %r in %r"
                      % (expected, func.__code__.co_consts))

    # Merging equal constants is not a strict requirement for the Python
    # semantics, it's a more an implementation detail.
    @support.cpython_only
    def test_merge_constants(self):
        # Issue #25843: compile() must merge constants which are equal
        # and have the same type.

        def check_same_constant(const):
            ns = {}
            code = "f1, f2 = lambda: %r, lambda: %r" % (const, const)
            exec(code, ns)
            f1 = ns['f1']
            f2 = ns['f2']
            self.assertIs(f1.__code__, f2.__code__)
            self.check_constant(f1, const)
            self.assertEqual(repr(f1()), repr(const))

        check_same_constant(None)
        check_same_constant(0)
        check_same_constant(0.0)
        check_same_constant(b'abc')
        check_same_constant('abc')

        # Note: "lambda: ..." emits "LOAD_CONST Ellipsis",
        # whereas "lambda: Ellipsis" emits "LOAD_GLOBAL Ellipsis"
        f1, f2 = lambda: ..., lambda: ...
        self.assertIs(f1.__code__, f2.__code__)
        self.check_constant(f1, Ellipsis)
        self.assertEqual(repr(f1()), repr(Ellipsis))

        # Merge constants in tuple or frozenset
        f1, f2 = lambda: "not a name", lambda: ("not a name",)
        f3 = lambda x: x in {("not a name",)}
        self.assertIs(f1.__code__.co_consts[1],
                      f2.__code__.co_consts[1][0])
        self.assertIs(next(iter(f3.__code__.co_consts[1])),
                      f2.__code__.co_consts[1])

        # {0} is converted to a constant frozenset({0}) by the peephole
        # optimizer
        f1, f2 = lambda x: x in {0}, lambda x: x in {0}
        self.assertIs(f1.__code__, f2.__code__)
        self.check_constant(f1, frozenset({0}))
        self.assertTrue(f1(0))

    # This is a regression test for a CPython specific peephole optimizer
    # implementation bug present in a few releases.  It's assertion verifies
    # that peephole optimization was actually done though that isn't an
    # indication of the bugs presence or not (crashing is).
    @support.cpython_only
    def test_peephole_opt_unreachable_code_array_access_in_bounds(self):
        """Regression test for issue35193 when run under clang msan."""
        def unused_code_at_end():
            return 3
            raise RuntimeError("unreachable")
        # The above function definition will trigger the out of bounds
        # bug in the peephole optimizer as it scans opcodes past the
        # RETURN_VALUE opcode.  This does not always crash an interpreter.
        # When you build with the clang memory sanitizer it reliably aborts.
        self.assertEqual(
            'RETURN_VALUE',
            list(dis.get_instructions(unused_code_at_end))[-1].opname)

    def test_dont_merge_constants(self):
        # Issue #25843: compile() must not merge constants which are equal
        # but have a different type.

        def check_different_constants(const1, const2):
            ns = {}
            exec("f1, f2 = lambda: %r, lambda: %r" % (const1, const2), ns)
            f1 = ns['f1']
            f2 = ns['f2']
            self.assertIsNot(f1.__code__, f2.__code__)
            self.assertNotEqual(f1.__code__, f2.__code__)
            self.check_constant(f1, const1)
            self.check_constant(f2, const2)
            self.assertEqual(repr(f1()), repr(const1))
            self.assertEqual(repr(f2()), repr(const2))

        check_different_constants(0, 0.0)
        check_different_constants(+0.0, -0.0)
        check_different_constants((0,), (0.0,))
        check_different_constants('a', b'a')
        check_different_constants(('a',), (b'a',))

        # check_different_constants() cannot be used because repr(-0j) is
        # '(-0-0j)', but when '(-0-0j)' is evaluated to 0j: we loose the sign.
        f1, f2 = lambda: +0.0j, lambda: -0.0j
        self.assertIsNot(f1.__code__, f2.__code__)
        self.check_constant(f1, +0.0j)
        self.check_constant(f2, -0.0j)
        self.assertEqual(repr(f1()), repr(+0.0j))
        self.assertEqual(repr(f2()), repr(-0.0j))

        # {0} is converted to a constant frozenset({0}) by the peephole
        # optimizer
        f1, f2 = lambda x: x in {0}, lambda x: x in {0.0}
        self.assertIsNot(f1.__code__, f2.__code__)
        self.check_constant(f1, frozenset({0}))
        self.check_constant(f2, frozenset({0.0}))
        self.assertTrue(f1(0))
        self.assertTrue(f2(0.0))

    def test_path_like_objects(self):
        # An implicit test for PyUnicode_FSDecoder().
        compile("42", FakePath("test_compile_pathlike"), "single")

    def test_stack_overflow(self):
        # bpo-31113: Stack overflow when compile a long sequence of
        # complex statements.
        compile("if a: b\n" * 200000, "<dummy>", "exec")

    # Multiple users rely on the fact that CPython does not generate
    # bytecode for dead code blocks. See bpo-37500 for more context.
    @support.cpython_only
    def test_dead_blocks_do_not_generate_bytecode(self):
        def unused_block_if():
            if 0:
                return 42

        def unused_block_while():
            while 0:
                return 42

        def unused_block_if_else():
            if 1:
                return None
            else:
                return 42

        def unused_block_while_else():
            while 1:
                return None
            else:
                return 42

        funcs = [unused_block_if, unused_block_while,
                 unused_block_if_else, unused_block_while_else]

        for func in funcs:
            opcodes = list(dis.get_instructions(func))
            self.assertEqual(2, len(opcodes))
            self.assertEqual('LOAD_CONST', opcodes[0].opname)
            self.assertEqual(None, opcodes[0].argval)
            self.assertEqual('RETURN_VALUE', opcodes[1].opname)


class TestExpressionStackSize(unittest.TestCase):
    # These tests check that the computed stack size for a code object
    # stays within reasonable bounds (see issue #21523 for an example
    # dysfunction).
    N = 100

    def check_stack_size(self, code):
        # To assert that the alleged stack size is not O(N), we
        # check that it is smaller than log(N).
        if isinstance(code, str):
            code = compile(code, "<foo>", "single")
        max_size = math.ceil(math.log(len(code.co_code)))
        self.assertLessEqual(code.co_stacksize, max_size)

    def test_and(self):
        self.check_stack_size("x and " * self.N + "x")

    def test_or(self):
        self.check_stack_size("x or " * self.N + "x")

    def test_and_or(self):
        self.check_stack_size("x and x or " * self.N + "x")

    def test_chained_comparison(self):
        self.check_stack_size("x < " * self.N + "x")

    def test_if_else(self):
        self.check_stack_size("x if x else " * self.N + "x")

    def test_binop(self):
        self.check_stack_size("x + " * self.N + "x")

    def test_func_and(self):
        code = "def f(x):\n"
        code += "   x and x\n" * self.N
        self.check_stack_size(code)


class TestStackSizeStability(unittest.TestCase):
    # Check that repeating certain snippets doesn't increase the stack size
    # beyond what a single snippet requires.

    def check_stack_size(self, snippet, async_=False):
        def compile_snippet(i):
            ns = {}
            script = """def func():\n""" + i * snippet
            if async_:
                script = "async " + script
            code = compile(script, "<script>", "exec")
            exec(code, ns, ns)
            return ns['func'].__code__

        sizes = [compile_snippet(i).co_stacksize for i in range(2, 5)]
        if len(set(sizes)) != 1:
            import dis, io
            out = io.StringIO()
            dis.dis(compile_snippet(1), file=out)
            self.fail("stack sizes diverge with # of consecutive snippets: "
                      "%s\n%s\n%s" % (sizes, snippet, out.getvalue()))

    def test_if(self):
        snippet = """
            if x:
                a
            """
        self.check_stack_size(snippet)

    def test_if_else(self):
        snippet = """
            if x:
                a
            elif y:
                b
            else:
                c
            """
        self.check_stack_size(snippet)

    def test_try_except_bare(self):
        snippet = """
            try:
                a
            except:
                b
            """
        self.check_stack_size(snippet)

    def test_try_except_qualified(self):
        snippet = """
            try:
                a
            except ImportError:
                b
            except:
                c
            else:
                d
            """
        self.check_stack_size(snippet)

    def test_try_except_as(self):
        snippet = """
            try:
                a
            except ImportError as e:
                b
            except:
                c
            else:
                d
            """
        self.check_stack_size(snippet)

    def test_try_finally(self):
        snippet = """
                try:
                    a
                finally:
                    b
            """
        self.check_stack_size(snippet)

    def test_with(self):
        snippet = """
            with x as y:
                a
            """
        self.check_stack_size(snippet)

    def test_while_else(self):
        snippet = """
            while x:
                a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for(self):
        snippet = """
            for x in y:
                a
            """
        self.check_stack_size(snippet)

    def test_for_else(self):
        snippet = """
            for x in y:
                a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for_break_continue(self):
        snippet = """
            for x in y:
                if z:
                    break
                elif u:
                    continue
                else:
                    a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for_break_continue_inside_try_finally_block(self):
        snippet = """
            for x in y:
                try:
                    if z:
                        break
                    elif u:
                        continue
                    else:
                        a
                finally:
                    f
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for_break_continue_inside_finally_block(self):
        snippet = """
            for x in y:
                try:
                    t
                finally:
                    if z:
                        break
                    elif u:
                        continue
                    else:
                        a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for_break_continue_inside_except_block(self):
        snippet = """
            for x in y:
                try:
                    t
                except:
                    if z:
                        break
                    elif u:
                        continue
                    else:
                        a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_for_break_continue_inside_with_block(self):
        snippet = """
            for x in y:
                with c:
                    if z:
                        break
                    elif u:
                        continue
                    else:
                        a
            else:
                b
            """
        self.check_stack_size(snippet)

    def test_return_inside_try_finally_block(self):
        snippet = """
            try:
                if z:
                    return
                else:
                    a
            finally:
                f
            """
        self.check_stack_size(snippet)

    def test_return_inside_finally_block(self):
        snippet = """
            try:
                t
            finally:
                if z:
                    return
                else:
                    a
            """
        self.check_stack_size(snippet)

    def test_return_inside_except_block(self):
        snippet = """
            try:
                t
            except:
                if z:
                    return
                else:
                    a
            """
        self.check_stack_size(snippet)

    def test_return_inside_with_block(self):
        snippet = """
            with c:
                if z:
                    return
                else:
                    a
            """
        self.check_stack_size(snippet)

    def test_async_with(self):
        snippet = """
            async with x as y:
                a
            """
        self.check_stack_size(snippet, async_=True)

    def test_async_for(self):
        snippet = """
            async for x in y:
                a
            """
        self.check_stack_size(snippet, async_=True)

    def test_async_for_else(self):
        snippet = """
            async for x in y:
                a
            else:
                b
            """
        self.check_stack_size(snippet, async_=True)

    def test_for_break_continue_inside_async_with_block(self):
        snippet = """
            for x in y:
                async with c:
                    if z:
                        break
                    elif u:
                        continue
                    else:
                        a
            else:
                b
            """
        self.check_stack_size(snippet, async_=True)

    def test_return_inside_async_with_block(self):
        snippet = """
            async with c:
                if z:
                    return
                else:
                    a
            """
        self.check_stack_size(snippet, async_=True)


if __name__ == "__main__":
    unittest.main()