bpo-31183: `dis` now handles coroutines & async generators (GH-3077)

Coroutines and async generators use a distinct attribute name for their
code objects, so this updates the `dis` module to correctly disassemble
objects with those attributes.

Due to the increase in the test module length, it also fixes some latent
defects in the tests related to how the displayed source line numbers
are extracted.

https://bugs.python.org/issue31230 is a follow-up issue suggesting we
may want to solve this a different way, by instead giving all these object
types a common `__code__` attribute, avoiding the need for special
casing in the `dis` module.

2 files changed, 57 insertions, 17 deletions

diff --git a/Lib/dis.py b/Lib/dis.py
index b990839..90ddf4f 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -32,20 +32,30 @@ def _try_compile(source, name):
     return c
 
 def dis(x=None, *, file=None, depth=None):
-    """Disassemble classes, methods, functions, generators, or code.
+    """Disassemble classes, methods, functions, and other compiled objects.
 
     With no argument, disassemble the last traceback.
 
+    Compiled objects currently include generator objects, async generator
+    objects, and coroutine objects, all of which store their code object
+    in a special attribute.
     """
     if x is None:
         distb(file=file)
         return
-    if hasattr(x, '__func__'):  # Method
+    # Extract functions from methods.
+    if hasattr(x, '__func__'):
         x = x.__func__
-    if hasattr(x, '__code__'):  # Function
+    # Extract compiled code objects from...
+    if hasattr(x, '__code__'):  # ...a function, or
         x = x.__code__
-    if hasattr(x, 'gi_code'):  # Generator
+    elif hasattr(x, 'gi_code'):  #...a generator object, or
         x = x.gi_code
+    elif hasattr(x, 'ag_code'):  #...an asynchronous generator object, or
+        x = x.ag_code
+    elif hasattr(x, 'cr_code'):  #...a coroutine.
+        x = x.cr_code
+    # Perform the disassembly.
     if hasattr(x, '__dict__'):  # Class or module
         items = sorted(x.__dict__.items())
         for name, x1 in items:
@@ -107,16 +117,24 @@ def pretty_flags(flags):
     return ", ".join(names)
 
 def _get_code_object(x):
-    """Helper to handle methods, functions, generators, strings and raw code objects"""
-    if hasattr(x, '__func__'): # Method
+    """Helper to handle methods, compiled or raw code objects, and strings."""
+    # Extract functions from methods.
+    if hasattr(x, '__func__'):
         x = x.__func__
-    if hasattr(x, '__code__'): # Function
+    # Extract compiled code objects from...
+    if hasattr(x, '__code__'):  # ...a function, or
         x = x.__code__
-    if hasattr(x, 'gi_code'):  # Generator
+    elif hasattr(x, 'gi_code'):  #...a generator object, or
         x = x.gi_code
-    if isinstance(x, str):     # Source code
+    elif hasattr(x, 'ag_code'):  #...an asynchronous generator object, or
+        x = x.ag_code
+    elif hasattr(x, 'cr_code'):  #...a coroutine.
+        x = x.cr_code
+    # Handle source code.
+    if isinstance(x, str):
         x = _try_compile(x, "<disassembly>")
-    if hasattr(x, 'co_code'):  # Code object
+    # By now, if we don't have a code object, we can't disassemble x.
+    if hasattr(x, 'co_code'):
         return x
     raise TypeError("don't know how to disassemble %s objects" %
                     type(x).__name__)
@@ -443,8 +461,8 @@ def findlinestarts(code):
 class Bytecode:
     """The bytecode operations of a piece of code
 
-    Instantiate this with a function, method, string of code, or a code object
-    (as returned by compile()).
+    Instantiate this with a function, method, other compiled object, string of
+    code, or a code object (as returned by compile()).
 
     Iterating over this yields the bytecode operations as Instruction instances.
     """
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index 254b317..bfbbee2 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -331,6 +331,13 @@ dis_fstring = """\
 def _g(x):
     yield x
 
+async def _ag(x):
+    yield x
+
+async def _co(x):
+    async for item in _ag(x):
+        pass
+
 def _h(y):
     def foo(x):
         '''funcdoc'''
@@ -390,6 +397,7 @@ Disassembly of <code object <listcomp> at 0x..., file "%s", line %d>:
        _h.__code__.co_firstlineno + 3,
 )
 
+
 class DisTests(unittest.TestCase):
 
     maxDiff = None
@@ -531,10 +539,22 @@ class DisTests(unittest.TestCase):
         self.do_disassembly_test(_C.cm, dis_c_class_method)
 
     def test_disassemble_generator(self):
-        gen_func_disas = self.get_disassembly(_g)  # Disassemble generator function
-        gen_disas = self.get_disassembly(_g(1))  # Disassemble generator itself
+        gen_func_disas = self.get_disassembly(_g)  # Generator function
+        gen_disas = self.get_disassembly(_g(1))  # Generator iterator
         self.assertEqual(gen_disas, gen_func_disas)
 
+    def test_disassemble_async_generator(self):
+        agen_func_disas = self.get_disassembly(_ag)  # Async generator function
+        agen_disas = self.get_disassembly(_ag(1))  # Async generator iterator
+        self.assertEqual(agen_disas, agen_func_disas)
+
+    def test_disassemble_coroutine(self):
+        coro_func_disas = self.get_disassembly(_co)  # Coroutine function
+        coro = _co(1)  # Coroutine object
+        coro.close()  # Avoid a RuntimeWarning (never awaited)
+        coro_disas = self.get_disassembly(coro)
+        self.assertEqual(coro_disas, coro_func_disas)
+
     def test_disassemble_fstring(self):
         self.do_disassembly_test(_fstring, dis_fstring)
 
@@ -1051,11 +1071,13 @@ class BytecodeTests(unittest.TestCase):
 
     def test_source_line_in_disassembly(self):
         # Use the line in the source code
-        actual = dis.Bytecode(simple).dis()[:3]
-        expected = "{:>3}".format(simple.__code__.co_firstlineno)
+        actual = dis.Bytecode(simple).dis()
+        actual = actual.strip().partition(" ")[0]  # extract the line no
+        expected = str(simple.__code__.co_firstlineno)
         self.assertEqual(actual, expected)
         # Use an explicit first line number
-        actual = dis.Bytecode(simple, first_line=350).dis()[:3]
+        actual = dis.Bytecode(simple, first_line=350).dis()
+        actual = actual.strip().partition(" ")[0]  # extract the line no
         self.assertEqual(actual, "350")
 
     def test_info(self):