fix(bindings): exclude preserve_none instruction from bindings

build.rs

@@ -227,6 +227,9 @@ fn generate_bindings(defines: &[(&str, &str)], includes: &[PathBuf]) -> Result<S
                 .map(|inc| format!("-I{}", inc.to_string_lossy())),
         )
         .clang_args(defines.iter().map(|(var, val)| format!("-D{var}={val}")))
+        // Define __bindgen so wrapper.h can detect it's being processed by bindgen
+        // and undefine HAVE_MUSTTAIL to prevent the preserve_none calling convention.
+        .clang_arg("-D__bindgen")
         .formatter(bindgen::Formatter::Rustfmt)
         .no_copy("php_ini_builder")
         .no_copy("_zval_struct")

src/wrapper.h

@@ -25,6 +25,16 @@
 #define __clang__
 #endif
 
+// Undefine HAVE_MUSTTAIL for bindgen to prevent PHP from using TAILCALL VM mode
+// with the `preserve_none` calling convention which bindgen 0.72.x doesn't support.
+// PHP 8.5+ on macOS ARM64 enables TAILCALL when both HAVE_MUSTTAIL and
+// HAVE_PRESERVE_NONE are defined, causing bindgen to panic on unknown calling
+// convention 20. This only affects binding generation, not PHP's runtime behavior.
+// See: https://github.com/php/php-src/blob/PHP-8.5/Zend/zend_vm_opcodes.h#L45-L46
+#if defined(__bindgen)
+#undef HAVE_MUSTTAIL
+#endif
+
 #include "php.h"
 
 #include "ext/standard/info.h"