Initial support for abi3t, depends on unreleased PyO3 features.

src/binding_generator/pyo3_binding.rs

@@ -38,6 +38,7 @@ pub struct Pyo3BindingGenerator<'a> {
 
 enum BindingType<'a> {
     Abi3(Option<&'a PythonInterpreter>),
+    Abi3t(Option<&'a PythonInterpreter>),
     VersionSpecific(&'a PythonInterpreter),
 }
 
@@ -50,6 +51,7 @@ impl<'a> Pyo3BindingGenerator<'a> {
         let binding_type = match stable_abi {
             Some(kind) => match kind {
                 StableAbiKind::Abi3 => BindingType::Abi3(interpreter),
+                StableAbiKind::Abi3t => BindingType::Abi3t(interpreter),
             },
             None => {
                 let interpreter = interpreter.ok_or_else(|| {
@@ -102,6 +104,7 @@ impl<'a> BindingGenerator for Pyo3BindingGenerator<'a> {
 
         let so_filename = match self.binding_type {
             BindingType::Abi3(interpreter) => ext_suffix(target, interpreter, ext_name, "abi3"),
+            BindingType::Abi3t(interpreter) => ext_suffix(target, interpreter, ext_name, "abi3t"),
             BindingType::VersionSpecific(interpreter) => interpreter.get_library_name(ext_name),
         };
         let artifact_target = ArtifactTarget::ExtensionModule(module.join(so_filename));

src/bridge/detection.rs

@@ -184,7 +184,7 @@ fn has_stable_abi(
     if abi3.is_some() {
         return Ok(abi3);
     }
-    Ok(None)
+    has_stable_abi_from_kind(deps, extra_features, StableAbiKind::Abi3t)
 }
 
 /// pyo3 supports building stable abi wheels if the unstable-api feature is not selected

src/bridge/mod.rs

@@ -131,6 +131,14 @@ impl StableAbi {
             version: StableAbiVersion::Version(major, minor),
         }
     }
+
+    /// Create a StableAbi instance from a known abi3t version
+    pub fn from_abi3t_version(major: u8, minor: u8) -> StableAbi {
+        StableAbi {
+            kind: StableAbiKind::Abi3t,
+            version: StableAbiVersion::Version(major, minor),
+        }
+    }
 }
 
 /// Python version to use as the abi3/abi3t target.
@@ -145,7 +153,7 @@ pub enum StableAbiVersion {
 }
 
 impl StableAbiVersion {
-    /// Convert `StableAbiVersion` into an Option, where CurrentPython maps None
+    /// Convert `StableAbiVersion` into an Option, where CurrentPython maps to None
     pub fn min_version(&self) -> Option<(u8, u8)> {
         match self {
             StableAbiVersion::CurrentPython => None,
@@ -159,12 +167,15 @@ impl StableAbiVersion {
 pub enum StableAbiKind {
     /// The original stable ABI, supporting Python 3.2 and up
     Abi3,
+    /// The free-threaded stable ABI, supporting Python 3.15 and up
+    Abi3t,
 }
 
 impl fmt::Display for StableAbiKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             StableAbiKind::Abi3 => write!(f, "abi3"),
+            StableAbiKind::Abi3t => write!(f, "abi3t"),
         }
     }
 }
@@ -174,6 +185,7 @@ impl StableAbiKind {
     pub fn wheel_tag(&self) -> &str {
         match self {
             StableAbiKind::Abi3 => "abi3",
+            StableAbiKind::Abi3t => "abi3.abi3t",
         }
     }
 }
@@ -341,6 +353,7 @@ impl BridgeModel {
             .and_then(|pyo3| match pyo3.stable_abi {
                 Some(stable_abi) => match stable_abi.kind {
                     StableAbiKind::Abi3 => Some(true),
+                    _ => None,
                 },
                 None => None,
             })

src/build_orchestrator.rs

@@ -286,15 +286,15 @@ impl<'a> BuildOrchestrator<'a> {
                 let interp = &self.context.python.interpreter[0];
                 match bindings.stable_abi {
                     Some(stable_abi) => {
-                        let wheel_tag = stable_abi.kind.wheel_tag();
+                        let abi_tag = stable_abi.kind.wheel_tag();
 
                         match stable_abi.version {
                             StableAbiVersion::Version(major, minor) => {
-                                vec![format!("cp{major}{minor}-{wheel_tag}-{platform}")]
+                                vec![format!("cp{major}{minor}-{abi_tag}-{platform}")]
                             }
                             StableAbiVersion::CurrentPython => {
                                 vec![format!(
-                                    "cp{major}{minor}-{wheel_tag}-{platform}",
+                                    "cp{major}{minor}-{abi_tag}-{platform}",
                                     major = interp.major,
                                     minor = interp.minor
                                 )]