Fix error message for pyemscripten abi incompatibility

Author: hoodmane

CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- Incompatibility errors for `pyemscripten_*` / `pyodide_*` (PEP 783) platform
+  wheels now report a meaningful Pyodide ABI version mismatch instead of a
+  garbled message such as `Wheel was built with Emscripten vpyemscripten.2026.0`.
+
 ### Changed
 
 - `install` now raises a helpful `ValueError` when given a VCS URL

micropip/_utils.py

@@ -171,26 +171,55 @@ def check_compatible(filename: str) -> None:
         raise ValueError(f"Wheel version is invalid: {filename!r}") from None
 
     tag: Tag = next(iter(tags))
-    if "emscripten" not in tag.platform:
-        raise ValueError(
-            f"Wheel platform '{tag.platform}' is not compatible with "
-            f"Pyodide's platform '{get_platform()}'"
-        )
+    platform = tag.platform
+
+    # PEP 783 Pyodide ABI platform tags, e.g. ``pyemscripten_2026_0_wasm32`` or
+    # ``pyodide_2026_0_wasm32``. These encode the Pyodide ABI version rather than
+    # the underlying Emscripten version, so they must be compared against the
+    # runtime's ABI version, not its Emscripten version.
+    pyodide_abi_prefixes = ("pyemscripten_", "pyodide_")
+    if platform.startswith(pyodide_abi_prefixes):
+
+        def platform_to_abi_version(platform: str) -> str:
+            for prefix in pyodide_abi_prefixes:
+                platform = platform.removeprefix(prefix)
+            return platform.removesuffix("_wasm32").replace("_", ".")
+
+        wheel_abi_version = platform_to_abi_version(platform)
+        runtime_abi_version = get_config_var(
+            "PYEMSCRIPTEN_PLATFORM_VERSION"
+        ) or get_config_var("PYODIDE_ABI_VERSION")
+        if runtime_abi_version:
+            runtime_abi_version = runtime_abi_version.replace("_", ".")
+        if wheel_abi_version != runtime_abi_version:
+            raise ValueError(
+                f"Wheel was built with Pyodide ABI version {wheel_abi_version} but "
+                f"the current environment has Pyodide ABI version "
+                f"{runtime_abi_version}"
+            )
 
-    def platform_to_version(platform: str) -> str:
-        return (
-            platform.replace("-", "_")
-            .removeprefix("emscripten_")
-            .removesuffix("_wasm32")
-            .replace("_", ".")
-        )
+    elif "emscripten" in platform:
 
-    wheel_emscripten_version = platform_to_version(tag.platform)
-    pyodide_emscripten_version = platform_to_version(get_platform())
-    if wheel_emscripten_version != pyodide_emscripten_version:
+        def platform_to_version(platform: str) -> str:
+            return (
+                platform.replace("-", "_")
+                .removeprefix("emscripten_")
+                .removesuffix("_wasm32")
+                .replace("_", ".")
+            )
+
+        wheel_emscripten_version = platform_to_version(platform)
+        pyodide_emscripten_version = platform_to_version(get_platform())
+        if wheel_emscripten_version != pyodide_emscripten_version:
+            raise ValueError(
+                f"Wheel was built with Emscripten v{wheel_emscripten_version} but "
+                f"Pyodide was built with Emscripten v{pyodide_emscripten_version}"
+            )
+
+    else:
         raise ValueError(
-            f"Wheel was built with Emscripten v{wheel_emscripten_version} but "
-            f"Pyodide was built with Emscripten v{pyodide_emscripten_version}"
+            f"Wheel platform '{platform}' is not compatible with "
+            f"Pyodide's platform '{get_platform()}'"
         )
 
     abi_incompatible = True

tests/test_utils.py

@@ -118,6 +118,31 @@ def test_check_compatible_wasm32(selenium_standalone_micropip):
     check_compatible(wheel_name)
 
 
+@pytest.mark.parametrize("prefix", ["pyemscripten", "pyodide"])
+def test_check_compatible_abi_version_mismatch(monkeypatch, prefix):
+    """
+    A wheel built for a different Pyodide ABI version should report the ABI
+    version mismatch instead of garbling it into an Emscripten version.
+    """
+    import micropip._utils as _utils
+    from micropip._utils import check_compatible
+
+    monkeypatch.setattr(
+        _utils,
+        "get_config_var",
+        lambda name: "2026_0"
+        if name in ("PYEMSCRIPTEN_PLATFORM_VERSION", "PYODIDE_ABI_VERSION")
+        else None,
+    )
+
+    wheel_name = f"pkg-1.0.0-{CPVER}-{CPVER}-{prefix}_2025_0_wasm32.whl"
+    with raiseValueError(
+        "Wheel was built with Pyodide ABI version 2025.0 but the current "
+        "environment has Pyodide ABI version 2026.0"
+    ):
+        check_compatible(wheel_name)
+
+
 _best_tag_test_cases = (
     "package, version, incompatible_tags, compatible_tags",
     # Tests assume that `compatible_tags` is sorted from least to most compatible: