From 7c087a24c4f56847cd464fcb5ef3762840c67eb8 Mon Sep 17 00:00:00 2001
From: armorbreak001 <contact@agentvote.cc>
Date: Wed, 22 Apr 2026 19:57:13 +0800
Subject: [PATCH] fix(markers): handle version pattern on LHS when marker
 variable is on RHS

When a marker like "'3.12.*' == python_full_version" is evaluated,
the variable is on the RHS so the resolved env value (e.g. '3.12.3')
was used as the specifier pattern while the literal ('3.12.*') was
treated as the item to check. Since '3.12.*' is not a valid PEP 440
version, Specifier.contains() silently returned False.

Now try building the specifier from lhs when the first attempt doesn't
match and lhs doesn't parse as a concrete version.
---
 src/packaging/markers.py | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/packaging/markers.py b/src/packaging/markers.py
index 65d7f330b..6c926d2a0 100644
--- a/src/packaging/markers.py
+++ b/src/packaging/markers.py
@@ -14,6 +14,7 @@
 from ._parser import parse_marker as _parse_marker
 from ._tokenizer import ParserSyntaxError
 from .specifiers import InvalidSpecifier, Specifier
+from .version import Version, InvalidVersion
 from .utils import canonicalize_name
 
 __all__ = [
@@ -221,7 +222,24 @@ def _eval_op(lhs: str, op: Op, rhs: str | AbstractSet[str], *, key: str) -> bool
         except InvalidSpecifier:
             pass
         else:
-            return spec.contains(lhs, prereleases=True)
+            if spec.contains(lhs, prereleases=True):
+                return True
+            # When the marker variable is on the RHS, lhs may be a version
+            # pattern (e.g. "3.12.*") while rhs is the resolved env value.
+            # Building the specifier from rhs produced no match (above), so
+            # try building it from lhs instead — but only when lhs doesn't
+            # parse as a concrete version (to avoid wrong answers for
+            # asymmetric operators like "<" / ">").
+            try:
+                Version(lhs)
+            except InvalidVersion:
+                try:
+                    swapped = Specifier(f"{op_str}{lhs}")
+                except InvalidSpecifier:
+                    pass
+                else:
+                    if swapped.contains(rhs, prereleases=True):
+                        return True
 
     oper: Operator | None = _operators.get(op_str)
     if oper is None: