fix: ensure consistent enum constant types across platforms

On Windows MSVC, C enums are always `int` (i32), while on other
platforms bindgen may generate them as u32 for non-negative enums.
This causes type mismatches when code using the bindings expects u32.

Add `.default_enum_style(bindgen::EnumVariation::Consts)` and
`.translate_enum_integer_types(true)` to ensure consistent types
regardless of platform.

Author: kajukitli

build.rs

@@ -266,6 +266,11 @@ fn generate_bindings(out_dir: &Path, include_dir: &Path) {
     .allowlist_function("nghttp2_.*")
     .allowlist_type("nghttp2_.*")
     .allowlist_var("NGHTTP2_.*")
+    // Generate enum constants as consts with consistent types across platforms.
+    // Without this, MSVC generates i32 (C int) while other platforms may use u32,
+    // causing type mismatches when consuming code expects u32.
+    .default_enum_style(bindgen::EnumVariation::Consts)
+    .translate_enum_integer_types(true)
     // Opaque types that should not derive Copy
     .opaque_type("nghttp2_session")
     .opaque_type("nghttp2_rcbuf")