PEP 776: Remove all discussion of packaging (#4327)

Co-authored-by: Adam Turner <[email protected]>

Author: hoodmane

peps/pep-0776.rst

@@ -2,13 +2,13 @@ PEP: 776
 Title: Emscripten Support
 Author: Hood Chatham <roberthoodchatham at gmail.com>
 Sponsor: Łukasz Langa <lukasz at python.org>
-Discussions-To: https://discuss.python.org/t/84996
+Discussions-To: https://discuss.python.org/t/86276
 Status: Draft
-Type: Standards Track
-Topic: Packaging
+Type: Informational
 Created: 18-Mar-2025
 Python-Version: 3.14
-Post-History: `18-Mar-2025 <https://discuss.python.org/t/84996>`__
+Post-History: `18-Mar-2025 <https://discuss.python.org/t/84996>`__,
+              `28-Mar-2025 <https://discuss.python.org/t/86276>`__,
 
 Abstract
 ========
@@ -20,8 +20,17 @@ also maintains an Emscripten target.
 
 This PEP formalizes the addition of Tier 3 for Emscripten support in Python 3.14
 which `was approved by the Steering Council on October 25, 2024
-<https://github.com/python/steering-council/issues/256>`__. The goal is to allow
-Pyodide wheels to be uploaded to PyPI.
+<https://github.com/python/steering-council/issues/256>`__. The goals are:
+
+1. To describe the current state of the CPython Emscripten runtime
+2. To describe the current state of the Pyodide runtime
+3. To identify minor features to be upstreamed from the Pyodide runtime into the
+   CPython Emscripten runtime
+
+The minor features identified here are all features that could be implemented
+without a PEP. We discuss more significant runtime features that we would like
+to implement but we defer decisions on those features to subsequent PEPs.
+
 
 Motivation
 ==========
@@ -41,33 +50,6 @@ Emscripten platform.
 Emscripten and WASI are also the only supported platforms that offer any
 meaningful sandboxing.
 
-Goals
-=====
-
-It is our long term goal to upstream the entire Pyodide runtime into CPython,
-but this is out of scope for the present PEP. This PEP only attempts to
-establish the foundation for future work.
-
-Runtime Goals
--------------
-
-1. To describe the current state of the CPython Emscripten runtime
-2. To describe the current state of the Pyodide runtime
-3. To identify minor features to be upstreamed from the Pyodide runtime into the
-   CPython Emscripten runtime
-
-The minor features identified here are all features that could be implemented
-without a PEP. We discuss more significant runtime features that we would like
-to implement but we defer decisions on those features to subsequent PEPs.
-
-Packaging Goals
----------------
-
-1. To describe Pyodide's packaging tooling
-2. To describe Pyodide's wheel abi to a similar level of detail as the manylinux
-   PEPs
-3. For Pyodide wheels to be allowed for upload to PyPI
-
 
 Emscripten Platform Information
 ===============================
@@ -142,30 +124,6 @@ Because of these limitations, Pyodide standardizes a no-pthreads build of
 Python. If there is sufficient demand, a pthreads build with no dynamic loader
 could be added later.
 
-Emscripten ABI Compatibility
-----------------------------
-
-The Emscripten compiler has no ABI stability guarantees between versions. Many
-Emscripten updates are ABI compatible by chance, and the Rust Emscripten target
-behaves as if the ABI were stable with only `occasional negative consequences
-<https://github.com/rust-lang/rust/issues/131467>`__.
-
-There are several linker flags that adjust the Emscripten ABI, so Python
-packages built to run with Emscripten must make sure to match the ABI-sensitive
-linker flags used to compile the interpreter to avoid load-time or run-time
-errors. The Emscripten compiler continuously fixes bugs and adds support for new
-web platform features. Thus, there is significant benefit to being able to
-update the ABI.
-
-In order to balance the ABI stability needs of package maintainers with the ABI
-flexibility to allow the platform to move forward, Pyodide plans to adopt a new
-ABI for each feature release of Python.
-
-The Pyodide team also coordinates the ABI flags that Pyodide uses with the
-Emscripten ABI that Rust supports in order to ensure that we have support for
-the many popular Rust packages. Historically, most of the work for this has
-been related to unwinding ABIs. See for instance `this Rust Major Change
-Proposal <https://github.com/rust-lang/compiler-team/issues/801>`__.
 
 Development Tools
 -----------------
@@ -520,7 +478,7 @@ The following modules can be imported, but are not functional:
 as well as any functionality that requires these.
 
 The following are present but cannot be imported due to a dependency on the
-termios package which has been removed:
+termios module which has been removed:
 
 - pty
 - tty
@@ -638,110 +596,6 @@ buildbots, maintained by Russell Keith-Magee.
 CPython does not currently test Tier 3 platforms on GitHub Actions, but if this
 ever changes, their Linux runners are able to build and test Emscripten Python.
 
-Packaging
----------
-
-Existing Package Support
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-Pyodide currently maintains ports of 255 different packages at the time of this
-writing, including major scientific Python packages like NumPy, SciPy, pandas,
-Polars, scikit-learn, OpenCV, PyArrow, and Pillow as well as general purpose
-packages like aiohttp, Requests, Pydantic, cryptography, and orjson.
-
-About 60 packages are also testing against Pyodide in their CI, including NumPy,
-pandas, awkward-cpp, scikit-image, statsmodels, PyArrow, Hypothesis, and PyO3.
-
-Pyodide Wheel Tags
-~~~~~~~~~~~~~~~~~~
-
-Pyodide wheels will use ``pyodide_<abi>_wasm32`` as the platform tag. For
-example, ``pyodide_2025_0_wasm32``.
-
-With a fixed version of Emscripten, it is possible to link dynamic libraries
-that require a large number of distinct ABIs, depending on ABI-sensitive linker
-options and what versions of what static libraries are linked. It is our intent
-that the ``pyodide_2025_0`` specifies the particular ABI that will work with the
-Pyodide CPython runtime.
-
-For example, wheels with the following tags are compatible with Python 3.13
-Pyodide:
-
-- ``cp13-cp13-pyodide_2025_0_wasm32``
-- ``abi3-cp10-pyodide_2025_0_wasm32``
-
-As well as all non-platformed tags. To generate the list of compatible tags, one
-can use the following code::
-
-
-    from packaging.tags import cpython_tags, _generic_platforms
-
-    def _emscripten_platforms() -> Iterator[str]:
-        pyodide_abi_version = sysconfig.get_config_var("PYODIDE_ABI_VERSION")
-        if pyodide_abi_version:
-            yield f"pyodide_{pyodide_abi_version}_wasm32"
-        yield from _generic_platforms()
-
-    emscripten_tags = cpython_tags(platforms=_emscripten_platforms())
-
-This code will be added to `pypa/packaging
-<https://github.com/pypa/packaging/pull/804>`__.
-
-Emscripten Wheel ABI
-~~~~~~~~~~~~~~~~~~~~
-
-The specification of the ``pyodide_<abi>`` ABI includes:
-
-* Which version of the Emscripten compiler is used
-* What libraries are statically linked with the interpreter
-* What stack unwinding ABI is to be used
-* Which runtime platform features are required to be present
-
-and a handful of other similar details that affect the ABI.
-
-The ABI is selected by choosing the appropriate version of the Emscripten
-compiler and passing appropriate compiler and linker flags. It is possible for
-other people to build their own Python interpreter that is compatible with the
-Pyodide ABI, it is not necessary to use the Pyodide distribution itself.
-
-The ``pyodide build`` tool knows how to create wheels that match our ABI. Unlike
-with manylinux wheels, there is no need for a Docker container to build the
-``pyodide_<abi>`` wheels. All that is needed is a Linux machine and appropriate
-versions of Python, Node.js, and Emscripten.
-
-
-Package Installers
-~~~~~~~~~~~~~~~~~~
-
-Installers should use the ``_emscripten_platforms()`` function shown above to
-determine which platforms are compatible with an Emscripten build of CPython. In
-particular, the Pyodide ABI version is exposed via
-``sysconfig.get_config_var("PYODIDE_ABI_VERSION")``.
-
-
-Package indexes
-~~~~~~~~~~~~~~~
-
-We recommend that package indexes accept any wheel whose platform tag matches
-``pyodide_[0-9]+_[0-9]+_wasm32``. We recommend that package indexes continue not
-accepting wheels that match ``emscripten_[0-9]+_[0-9]+_[0-9]+_wasm32``.
-
-
-Dependency Specifier Markers
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-To check for the Emscripten platform in a dependency specifier, one can use
-``sys_platform == 'emscripten'`` (or its negation). Such checks are already in use
-in the wild and seem to be sufficient for the needs of the community.
-
-
-Trove Classifier
-~~~~~~~~~~~~~~~~
-
-Packages that build and test Emscripten wheels can declare this by adding the
-``Environment :: WebAssembly :: Emscripten``. PyPI already accepts uploads of
-packages with this classifier.
-
 
 PEP 11
 ------
@@ -836,10 +690,6 @@ care to minimize backwards incompatibility. We will also need a way to disable
 partially-upstreamed features so that Pyodide can replace them with more
 complete versions downstream.
 
-These backwards compatibility concerns impact not just the runtime but also the
-packaging system. Adding new platform tags should not affect existing packaging
-tools because tools ignore wheels with an unknown package tag.
-
 
 Security Implications
 =====================
@@ -861,12 +711,6 @@ to use them all at runtime. The documentation will cover this in a similar form
 to the existing Windows embeddable package. In the short term, we will encourage
 developers to use Pyodide if at all possible.
 
-Second, maintainers of packages with binary components need to know how to
-build, test, label, and deploy them for Emscripten (see Packaging). The Pyodide
-documentation on `building and testing packages
-<https://pyodide.org/en/stable/development/building-and-testing-packages.html>`__
-is the best reference for this.
-
 
 Reference Implementation
 ========================