code_richcompare() now uses the constants types

Issue #25843: When compiling code, don't merge constants if they are equal but
have a different types. For example, "f1, f2 = lambda: 1, lambda: 1.0" is now
correctly compiled to two different functions: f1() returns 1 (int) and f2()
returns 1.0 (int), even if 1 and 1.0 are equal.

Add a new _PyCode_ConstantKey() private function.

1 files changed, 59 insertions, 0 deletions

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index c9f2835..e954a0c 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -623,6 +623,65 @@ class TestStackSize(unittest.TestCase):
         code += "   x and x\n" * self.N
         self.check_stack_size(code)
 
+    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.
+    @test_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')
+
+    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.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() 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))
+
 
 def test_main():
     test_support.run_unittest(__name__)