Correct res type and change f var to empty

Author: fluhus

Lib/test/test_capi/test_opt.py

@@ -1443,19 +1443,19 @@ def f(n):
             for i in range(n):
                 dummy = "aaa"
                 # Hopefully the optimizer can't guess what the value is.
-                # f is always "", but we can only prove that it's a string:
-                f = dummy[:0]
+                # empty is always "", but we can only prove that it's a string:
+                empty = dummy[:0]
                 trace.append("A")
-                if not f:  # Kept.
+                if not empty:  # Kept.
                     trace.append("B")
-                    if not f:  # Removed!
+                    if not empty:  # Removed!
                         trace.append("C")
                     trace.append("D")
-                    if f:  # Removed!
+                    if empty:  # Removed!
                         trace.append("X")
                     trace.append("E")
                 trace.append("F")
-                if f:  # Removed!
+                if empty:  # Removed!
                     trace.append("X")
                 trace.append("G")
             return trace

Python/optimizer_bytecodes.c

@@ -438,7 +438,7 @@ dummy_func(void) {
             // removed and the narrowed value to be invalid:
             if (next_opcode == _GUARD_IS_FALSE_POP) {
                 sym_set_const(value, Py_GetConstant(Py_CONSTANT_EMPTY_STR));
-                res = sym_new_type(ctx, &PyUnicode_Type);
+                res = sym_new_type(ctx, &PyBool_Type);
             }
         }
     }