Reintroduce support for arch-suffixed factors

Apparently we need to support these.

Signed-off-by: Stephen Finucane <stephen@that.guru>

src/tox/tox_env/python/api.py

@@ -130,11 +130,34 @@ def default_base_python(self, conf: Config, env_name: str | None) -> list[str]:
     @classmethod
     def extract_base_python(cls, env_name: str) -> str | None:
         candidates: list[str] = []
-        for factor in env_name.split("-"):
+        factors = env_name.split("-")
+
+        def _parse_factor(factor: str) -> str | None:
             spec = PythonSpec.from_string_spec(factor)
             impl = spec.implementation or "python"
             if impl.lower() in INTERPRETER_SHORT_NAMES and env_name is not None and spec.path is None:
-                candidates.append(factor)
+                return factor
+            return None
+
+        # unfortunately we have an exception to the "factors are delimited by dashes" rule: the architecture
+        # we must support e.g. py38-64, which means python3.8 (64 bit)
+        if len(factors) > 1 and "32" in factors or "64" in factors:
+            for arch in {"32", "64"}:
+                if arch not in factors:
+                    continue
+                idx = factors.index(arch)
+                if idx == 0:
+                    continue
+                factor = "-".join([factors[idx - 1], factors[idx]])
+                candidate = _parse_factor(factor)
+                if candidate:
+                    candidates.append(candidate)
+                    del factors[idx - 1 : idx + 1]
+
+        for factor in factors:
+            candidate = _parse_factor(factor)
+            if candidate:
+                candidates.append(candidate)
         if candidates:
             if len(candidates) > 1:
                 raise ValueError(f"conflicting factors {', '.join(candidates)} in {env_name}")

tests/tox_env/python/test_python_api.py

@@ -99,6 +99,9 @@ def test_base_python_env_no_conflict(env: str, base_python: list[str], ignore_co
         ("py310", ["py38", "py39"], "py310", ["py38", "py39"]),
         ("py3.11.1", ["py3.11.2"], "py3.11.1", ["py3.11.2"]),
         ("py3-64", ["py3-32"], "py3-64", ["py3-32"]),
+        ("foo-py38-64-bar", ["python3"], "py38-64", ["python3"]),
+        ("foo-py36-32", ["python3"], "py36-32", ["python3"]),
+        ("py311-22", ["python3"], "py311", ["python3"]),
         ("py310-magic", ["py39"], "py310", ["py39"]),
     ],
     ids=lambda a: "|".join(a) if isinstance(a, list) else str(a),
@@ -110,7 +113,7 @@ def test_base_python_env_conflict(
     conflict: list[str],
     ignore_conflict: bool,
 ) -> None:
-    if env == "py3-64":
+    if env == "py311-22":
         raise pytest.skip("bug #2657")
 
     if ignore_conflict: