Update platform name to pyemscripten

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Platform name for the Pyodide wheel is now `pyemscripten` instead of `pyodide`, following the PEP 783 standard.
+  If you want to use the old platform name, you can set the `USE_LEGACY_PLATFORM` environment variable to `1`.
+  [#319](https://github.com/pyodide/pyodide-build/pull/319)
+
 ## [0.34.0] - 2026/03/31
 
 ### Added

pyodide_build/build_env.py

@@ -245,7 +245,10 @@ def platform() -> str:
 
 def wheel_platform() -> str:
     abi_version = get_build_flag("PYODIDE_ABI_VERSION")
-    return f"pyodide_{abi_version}_wasm32"
+    legacy_platform = to_bool(get_host_build_flag("USE_LEGACY_PLATFORM"))
+    if legacy_platform:
+        return f"pyodide_{abi_version}_wasm32"
+    return f"pyemscripten_{abi_version}_wasm32"
 
 
 def pyodide_tags_() -> Iterator[Tag]:

pyodide_build/config.py

@@ -252,6 +252,7 @@ def _parse_makefile_envs(
     "xbuildenv_path": "PYODIDE_XBUILDENV_PATH",
     "dist_dir": "PYODIDE_DIST_DIR",
     "ignored_build_requirements": "IGNORED_BUILD_REQUIREMENTS",
+    "use_legacy_platform": "USE_LEGACY_PLATFORM",
     # maintainer only
     "_f2c_fixes_wrapper": "_F2C_FIXES_WRAPPER",
 }
@@ -273,6 +274,7 @@ def _parse_makefile_envs(
     "default_cross_build_env_url",
     "xbuildenv_path",
     "ignored_build_requirements",
+    "use_legacy_platform",
     # maintainer only
     "_f2c_fixes_wrapper",
 }
@@ -297,6 +299,7 @@ def _parse_makefile_envs(
     "xbuildenv_path": "",
     # A list of PEP508 build-time requirements to be ignored when building a wheel
     "ignored_build_requirements": " ".join(BASE_IGNORED_REQUIREMENTS),
+    "use_legacy_platform": "0",
     # maintainer only
     "_f2c_fixes_wrapper": "",
 }

pyodide_build/out_of_tree/venv.py

@@ -8,7 +8,12 @@
 
 import virtualenv
 
-from pyodide_build.build_env import get_build_flag, get_pyodide_root, in_xbuildenv
+from pyodide_build.build_env import (
+    get_build_flag,
+    get_pyodide_root,
+    in_xbuildenv,
+    wheel_platform,
+)
 from pyodide_build.common import IS_WIN, run_command
 from pyodide_build.logger import logger
 
@@ -311,7 +316,7 @@ def _get_pip_monkeypatch(self) -> str:
         sysconfigdata_dir = Path(get_build_flag("TARGETINSTALLDIR")) / "sysconfigdata"
         pip_patched_name = self.pip_patched_path.name
         exe_suffix = self.exe_suffix
-        pyodide_platform = f"pyodide_{get_build_flag('PYODIDE_ABI_VERSION')}_wasm32"
+        pyodide_platform = wheel_platform()
         return dedent(
             """\
             import os
@@ -343,6 +348,7 @@ def get_executable():
             def _emscripten_platforms():
                 pyodide_abi_version = sysconfig.get_config_var("PYODIDE_ABI_VERSION")
                 if pyodide_abi_version:
+                    yield f"pyemscripten_{pyodide_abi_version}_wasm32"
                     yield f"pyodide_{pyodide_abi_version}_wasm32"
                 yield from tags._generic_platforms()
 

pyodide_build/tests/conftest.py

@@ -32,6 +32,7 @@ def _reset():
         build_env.get_host_build_environment_vars.cache_clear()
         build_env.get_build_environment_vars.cache_clear()
         build_env.get_unisolated_packages.cache_clear()
+        build_env.pyodide_tags.cache_clear()
         common.default_xbuildenv_path.cache_clear()
 
     _reset()

pyodide_build/tests/recipe/test_builder.py

@@ -219,11 +219,11 @@ def test_needs_rebuild(tmpdir, is_wheel):
         dist_dir = pkg_root / "dist"
         dist_dir.mkdir()
         # Build of current version with wrong abi
-        (dist_dir / "regex-12-cp311-cp311-pyodide_2024_0_wasm32.whl").touch()
+        (dist_dir / "regex-12-cp311-cp311-pyemscripten_2024_0_wasm32.whl").touch()
         # Build of old version with current abi
-        (dist_dir / "regex-11-cp312-cp312-pyodide_2024_0_wasm32.whl").touch()
+        (dist_dir / "regex-11-cp312-cp312-pyemscripten_2024_0_wasm32.whl").touch()
         # the version we're trying to build
-        packaged = dist_dir / "regex-12-cp312-cp312-pyodide_2024_0_wasm32.whl"
+        packaged = dist_dir / "regex-12-cp312-cp312-pyemscripten_2024_0_wasm32.whl"
     else:
         packaged = buildpath / ".packaged"
 

pyodide_build/tests/test_build_env.py

@@ -117,6 +117,51 @@ def test_get_build_environment_vars_host_env(
         assert "RANDOM_ENV" not in e
 
 
+class TestWheelPlatform:
+    def test_default_pyemscripten(self, dummy_xbuildenv, reset_env_vars, reset_cache):
+        abi_version = build_env.get_build_flag("PYODIDE_ABI_VERSION")
+        assert build_env.wheel_platform() == f"pyemscripten_{abi_version}_wasm32"
+
+    def test_legacy_pyodide(
+        self, dummy_xbuildenv, monkeypatch, reset_env_vars, reset_cache
+    ):
+        monkeypatch.setenv("USE_LEGACY_PLATFORM", "1")
+        build_env.get_host_build_environment_vars.cache_clear()
+        build_env.get_build_environment_vars.cache_clear()
+
+        abi_version = build_env.get_build_flag("PYODIDE_ABI_VERSION")
+        assert build_env.wheel_platform() == f"pyodide_{abi_version}_wasm32"
+
+    def test_pyodide_tags_include_both_platforms(
+        self, dummy_xbuildenv, reset_env_vars, reset_cache
+    ):
+        build_env.pyodide_tags.cache_clear()
+        tags = build_env.pyodide_tags()
+        platforms = {t.platform for t in tags}
+
+        emscripten_plat = build_env.platform()
+        wheel_plat = build_env.wheel_platform()
+
+        assert emscripten_plat in platforms
+        assert wheel_plat in platforms
+        assert wheel_plat.startswith("pyemscripten_")
+
+    def test_pyodide_tags_legacy_platform(
+        self, dummy_xbuildenv, monkeypatch, reset_env_vars, reset_cache
+    ):
+        monkeypatch.setenv("USE_LEGACY_PLATFORM", "1")
+        build_env.get_host_build_environment_vars.cache_clear()
+        build_env.get_build_environment_vars.cache_clear()
+        build_env.pyodide_tags.cache_clear()
+
+        tags = build_env.pyodide_tags()
+        platforms = {t.platform for t in tags}
+
+        wheel_plat = build_env.wheel_platform()
+        assert wheel_plat.startswith("pyodide_")
+        assert wheel_plat in platforms
+
+
 def test_wheel_paths(dummy_xbuildenv):
     from pathlib import Path
 

pyodide_build/tests/test_cli.py

@@ -659,7 +659,7 @@ def test_build_cpython_module(tmp_path, dummy_xbuildenv, mock_emscripten):
     results = list(dist_dir.glob("*.whl"))
     assert len(results) == 1
     result = results[0]
-    assert result.name == "pydecimal-1.0.0-cp312-cp312-pyodide_2024_0_wasm32.whl"
+    assert result.name == "pydecimal-1.0.0-cp312-cp312-pyemscripten_2024_0_wasm32.whl"
 
 
 def test_wheel_download_version_mismatch(tmp_path, dummy_xbuildenv, mock_emscripten):