From ada43c4f82b9df4e260f1368038c31cd55c4a61e Mon Sep 17 00:00:00 2001
From: Bas Schoenmaeckers <7943856+bschoenmaeckers@users.noreply.github.com>
Date: Fri, 2 Oct 2026 11:59:04 +0200
Subject: [PATCH] Add `PyABIInfo_Check` to the c-api (#8941)

---
 crates/capi/src/modsupport.rs | 59 ++++++++++++++++++++++++++++++++++-
 crates/capi/src/slots.rs      | 31 +-----------------
 2 files changed, 59 insertions(+), 31 deletions(-)

diff --git a/crates/capi/src/modsupport.rs b/crates/capi/src/modsupport.rs
index 469a6e639..509039777 100644
--- a/crates/capi/src/modsupport.rs
+++ b/crates/capi/src/modsupport.rs
@@ -3,8 +3,54 @@ use crate::object::PyTypeObject;
 use crate::pystate::with_vm;
 use crate::util::{CStrExt, FfiPtrExt};
 use core::ffi::{c_char, c_int, c_long};
-use rustpython_vm::AsObject;
 use rustpython_vm::builtins::PyModule;
+use rustpython_vm::{AsObject, PyResult, VirtualMachine};
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct PyABIInfo {
+    pub abiinfo_major_version: u8,
+    pub abiinfo_minor_version: u8,
+    pub flags: u16,
+    pub build_version: u32,
+    pub abi_version: u32,
+}
+
+impl PyABIInfo {
+    pub(crate) fn is_supported(
+        &self,
+        vm: &VirtualMachine,
+        module_name: Option<&str>,
+    ) -> PyResult<()> {
+        const PY_ABIINFO_STABLE: u16 = 0x0001;
+        const PY_ABIINFO_FREETHREADED: u16 = 0x0004;
+
+        let module_name = module_name.unwrap_or("<unknown>");
+
+        if self.abiinfo_major_version == 0 {
+            return Ok(());
+        }
+
+        if self.abiinfo_major_version > 1 {
+            return Err(
+                vm.new_import_error("PyABIInfo version too high", vm.ctx.new_str(module_name))
+            );
+        }
+
+        if self.flags & PY_ABIINFO_STABLE == 0 {
+            return Err(vm.new_import_error("not using stable ABI", vm.ctx.new_str(module_name)));
+        }
+
+        if self.flags & PY_ABIINFO_FREETHREADED == 0 {
+            return Err(vm.new_import_error(
+                "incompatible with free-threaded python",
+                vm.ctx.new_str(module_name),
+            ));
+        }
+
+        Ok(())
+    }
+}
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyModule_AddObjectRef(
@@ -84,6 +130,17 @@ pub unsafe extern "C" fn PyModule_AddType(
     })
 }
 
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn PyABIInfo_Check(
+    info: *mut PyABIInfo,
+    module_name: *const c_char,
+) -> c_int {
+    with_vm(|vm| {
+        let module_name = unsafe { module_name.try_as_str_opt(vm) }?;
+        unsafe { &*info }.is_supported(vm, module_name)
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use pyo3::prelude::*;
diff --git a/crates/capi/src/slots.rs b/crates/capi/src/slots.rs
index 73161c168..79b11c7b4 100644
--- a/crates/capi/src/slots.rs
+++ b/crates/capi/src/slots.rs
@@ -1,5 +1,6 @@
 use crate::PyObject;
 use crate::methodobject::PyMethodDef;
+use crate::modsupport::PyABIInfo;
 use crate::object::PyType_Slot;
 use crate::util::CStrExt;
 use core::ffi::{c_char, c_int, c_void};
@@ -129,36 +130,6 @@ pub union PySlotValue {
     pub sl_uint64: u64,
 }
 
-#[repr(C)]
-#[derive(Debug, Copy, Clone)]
-pub struct PyABIInfo {
-    pub abiinfo_major_version: u8,
-    pub abiinfo_minor_version: u8,
-    pub flags: u16,
-    pub build_version: u32,
-    pub abi_version: u32,
-}
-
-impl PyABIInfo {
-    #[allow(dead_code)]
-    #[must_use]
-    pub(crate) fn is_supported(&self) -> bool {
-        const PY_ABIINFO_STABLE: u16 = 0x0001;
-        const PY_ABIINFO_FREETHREADED: u16 = 0x0004;
-
-        if self.abiinfo_major_version != 1 || self.abiinfo_minor_version != 0 {
-            return false;
-        }
-
-        // Only accept abi3t
-        if self.flags & PY_ABIINFO_STABLE == 0 || self.flags & PY_ABIINFO_FREETHREADED == 0 {
-            return false;
-        }
-
-        true
-    }
-}
-
 #[allow(dead_code)]
 #[derive(Debug, Copy, Clone)]
 pub(crate) enum PySlotModule<'a> {