Add 3.15/3.15t torch validation for Linux x86 + aarch64 (test channel)

Add Python 3.15 and 3.15t to the test-channel validation matrix, scoped to
Linux x86 and aarch64 only. torchvision wheels are not published for these
versions yet, so the install command requests torch only.

- PYTHON_ARCHES_DICT["test"] gains 3.15 / 3.15t (nightly and release unchanged).
- LINUX_ONLY_PYTHON_ARCHES strips these from Windows/macOS matrices.
- TORCH_ONLY_PYTHON_ARCHES makes get_wheel_install_command request torch only.
- Add unit tests covering the OS scoping and torch-only install command.

Existing golden assets (generated with the nightly channel) are unchanged.

Author: atalman

tools/scripts/generate_binary_build_matrix.py

@@ -23,10 +23,20 @@
 
 PYTHON_ARCHES_DICT = {
     "nightly": ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"],
-    "test": ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"],
+    "test": ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t", "3.15", "3.15t"],
     "release": ["3.10", "3.11", "3.12", "3.13", "3.14", "3.14t"],
 }
 
+# Python versions validated on Linux (x86 and aarch64) only for now. They are
+# stripped from Windows and macOS matrices since torch wheels for these versions
+# are not built/validated there yet.
+LINUX_ONLY_PYTHON_ARCHES = ["3.15", "3.15t"]
+
+# Python versions for which only torch is validated (no torchvision). torchvision
+# wheels are not published for these versions yet, so the install command must
+# request torch alone.
+TORCH_ONLY_PYTHON_ARCHES = ["3.15", "3.15t"]
+
 MACOS_PYTHON_POINT_VERSIONS = {
     "3.10": "3.10.19",
     "3.11": "3.11.14",
@@ -293,6 +303,11 @@ def get_wheel_install_command(
         else PACKAGES_TO_INSTALL_WHL
     )
 
+    # Validate torch only (no torchvision) for versions without published
+    # torchvision wheels, e.g. 3.15 / 3.15t.
+    if python_version in TORCH_ONLY_PYTHON_ARCHES:
+        PACKAGES_TO_INSTALL = "torch"
+
     if (
         channel == RELEASE
         and (not use_only_dl_pytorch_org)
@@ -430,6 +445,13 @@ def generate_wheels_matrix(
     if os == WINDOWS_ARM64:
         python_versions = ["3.11", "3.12", "3.13"]  # only versions for now
 
+    # Restrict Linux-only Python versions (e.g. 3.15/3.15t) to the Linux x86 and
+    # aarch64 matrices so Windows/macOS validation is unaffected.
+    if os not in (LINUX, LINUX_AARCH64):
+        python_versions = [
+            pv for pv in python_versions if pv not in LINUX_ONLY_PYTHON_ARCHES
+        ]
+
     if os == LINUX:
         # NOTE: We only build manywheel packages for linux
         package_type = "manywheel"

tools/tests/test_generate_binary_build_matrix.py

@@ -126,6 +126,54 @@ def test_linux_wheel_cuda_xpu_nocpu(self):
             reference_output_file="build_matrix_linux_wheel_xpu.json",
         )
 
+    def _test_channel_python_versions(self, operating_system: str) -> set:
+        out = generate_build_matrix(
+            "wheel",
+            operating_system,
+            "test",
+            "enable",
+            "enable" if operating_system in ("linux",) else "disable",
+            "enable",
+            "enable" if operating_system in ("linux", "windows") else "disable",
+            "false",
+            "false",
+            "disable",
+        )
+        return {entry["python_version"] for entry in out["include"]}
+
+    def test_linux_only_python_arches_on_linux(self):
+        # 3.15 / 3.15t are validated on Linux x86 and aarch64 for the test channel.
+        for operating_system in ("linux", "linux-aarch64"):
+            versions = self._test_channel_python_versions(operating_system)
+            self.assertIn("3.15", versions)
+            self.assertIn("3.15t", versions)
+
+    def test_linux_only_python_arches_excluded_elsewhere(self):
+        # Windows and macOS must not pick up the Linux-only versions.
+        for operating_system in ("windows", "macos"):
+            versions = self._test_channel_python_versions(operating_system)
+            self.assertNotIn("3.15", versions)
+            self.assertNotIn("3.15t", versions)
+
+    def test_torch_only_install_command_for_linux_only_arches(self):
+        out = generate_build_matrix(
+            "wheel",
+            "linux",
+            "test",
+            "enable",
+            "enable",
+            "enable",
+            "enable",
+            "false",
+            "false",
+            "disable",
+        )
+        for entry in out["include"]:
+            if entry["python_version"] in ("3.15", "3.15t"):
+                # torchvision is not published for these versions yet.
+                self.assertNotIn("torchvision", entry["installation"])
+                self.assertIn("torch", entry["installation"])
+
 
 def parse_args():
     parser = argparse.ArgumentParser(description="Test generate build matrix")