gh-123363: Show string value of CONTAINS_OP oparg in dis (#123387)

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Lib/dis.py

@@ -52,6 +52,7 @@
 STORE_FAST_LOAD_FAST = opmap['STORE_FAST_LOAD_FAST']
 STORE_FAST_STORE_FAST = opmap['STORE_FAST_STORE_FAST']
 IS_OP = opmap['IS_OP']
+CONTAINS_OP = opmap['CONTAINS_OP']
 
 CACHE = opmap["CACHE"]
 
@@ -632,6 +633,8 @@ def get_argval_argrepr(self, op, arg, offset):
                 argrepr = _special_method_names[arg]
             elif deop == IS_OP:
                 argrepr = 'is not' if argval else 'is'
+            elif deop == CONTAINS_OP:
+                argrepr = 'not in' if argval else 'in'
         return argval, argrepr
 
 def get_instructions(x, *, first_line=None, show_caches=None, adaptive=False):

Lib/test/test_dis.py

@@ -2037,6 +2037,15 @@ def test_is_op_format(self):
         dis.dis("a is not b", file=output, show_caches=True)
         self.assertIn("IS_OP                    1 (is not)", output.getvalue())
 
+    def test_contains_op_format(self):
+        output = io.StringIO()
+        dis.dis("a in b", file=output, show_caches=True)
+        self.assertIn("CONTAINS_OP              0 (in)", output.getvalue())
+
+        output = io.StringIO()
+        dis.dis("a not in b", file=output, show_caches=True)
+        self.assertIn("CONTAINS_OP              1 (not in)", output.getvalue())
+
     def test_baseopname_and_baseopcode(self):
         # Standard instructions
         for name, code in dis.opmap.items():

Misc/NEWS.d/next/Library/2024-08-27-12-11-00.gh-issue-123363.gKuJp6.rst

@@ -0,0 +1,2 @@
+Show string value of :opcode:`CONTAINS_OP` oparg in :mod:`dis` output.
+Patch by Alexandr153.