From 3a6e16457d15dcdc8364b2869f0beecd79b186cb Mon Sep 17 00:00:00 2001
From: Agriya Khetarpal <74401230+agriyakhetarpal@users.noreply.github.com>
Date: Thu, 9 Jul 2026 22:10:41 +0530
Subject: [PATCH] Use PYODIDE environment variable for Emscripten
 cross-compilation detection

---
 mypy/options.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mypy/options.py b/mypy/options.py
index 2f03cd3eab5b7..92c9ea3b1701d 100644
--- a/mypy/options.py
+++ b/mypy/options.py
@@ -1,9 +1,9 @@
 from __future__ import annotations
 
+import os
 import pprint
 import re
 import sys
-import sysconfig
 from collections.abc import Callable
 from re import Pattern
 from typing import Any, Final
@@ -112,11 +112,11 @@ def __init__(self) -> None:
         # then mypy does not search for PEP 561 packages.
         self.python_executable: str | None = sys.executable
 
-        # When cross compiling to emscripten, we need to rely on MACHDEP because
-        # sys.platform is the host build platform, not emscripten.
-        MACHDEP = sysconfig.get_config_var("MACHDEP")
-        if MACHDEP == "emscripten":
-            self.platform = MACHDEP
+        # When cross compiling to emscripten, sys.platform is the host build
+        # platform, not emscripten. Pyodide sets the PYODIDE environment variable
+        # at build time, so we use it to detect the emscripten target.
+        if "PYODIDE" in os.environ:
+            self.platform = "emscripten"
         else:
             self.platform = sys.platform