Change bindgen to optional and keep the old method as default

Cargo.toml

@@ -33,7 +33,7 @@ opt-level = 2
 cc = "1"
 glob = "0.3"
 pkg-config = "0.3"
-bindgen = "0.72"
+bindgen = { version = "0.72", optional = true }
 
 [features]
 default = ["std", "parallel"]
@@ -44,3 +44,4 @@ sse41 = [] # x64 SSE 4.1 (will crash on x86 CPUs without it)
 avx2 = [] # x64 AVX2 (will crash on x86 CPUs without it)
 system-dylib = [
 ] # Use the system-installed dylib instead of compiling a static library from the vendor
+generate-bindings = ["dep:bindgen"] # Generate ffi.rs based on the compile target

build.rs

@@ -2,31 +2,11 @@ use std::env;
 use std::path::PathBuf;
 
 fn main() {
-    if cfg!(feature = "system-dylib") {
-        let lib_name = "libwebp";
-        let find_system_lib = pkg_config::Config::new().probe(lib_name).is_ok();
+    #[cfg(feature = "system-dylib")]
+    system_dylib();
 
-        if find_system_lib {
-            println!("cargo:rustc-link-lib={lib_name}");
-            return;
-        }
-    }
-
-    let bindings = bindgen::Builder::default()
-        .header("wrap.h")
-        .default_enum_style(bindgen::EnumVariation::Rust {
-            non_exhaustive: false,
-        })
-        .trust_clang_mangling(false)
-        .impl_debug(true)
-        .allowlist_function("[wW][eE][bB].*")
-        .allowlist_var("[wW][eE][bB].*")
-        .allowlist_type("[wW][eE][bB].*")
-        .use_core()
-        .generate()
-        .expect("Unable to generate bindings");
-
-    bindings.write_to_file("src/ffi.rs").unwrap();
+    #[cfg(feature = "generate-bindings")]
+    generate_bindings();
 
     let manifest_dir =
         PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR"));
@@ -56,6 +36,38 @@ fn main() {
     cc.compile("webpsys");
 }
 
+#[cfg(feature = "system-dylib")]
+fn system_dylib() {
+    let lib_name = "libwebp";
+    let find_system_lib = pkg_config::Config::new().probe(lib_name).is_ok();
+
+    if find_system_lib {
+        println!("cargo:rustc-link-lib={lib_name}");
+        return;
+    }
+}
+
+#[cfg(feature = "generate-bindings")]
+fn generate_bindings() {
+    let bindings = bindgen::Builder::default()
+        .header("wrap.h")
+        .default_enum_style(bindgen::EnumVariation::Rust {
+            non_exhaustive: false,
+        })
+        .trust_clang_mangling(false)
+        .impl_debug(true)
+        .allowlist_function("[wW][eE][bB].*")
+        .allowlist_var("[wW][eE][bB].*")
+        .allowlist_type("[wW][eE][bB].*")
+        .use_core()
+        .generate()
+        .expect("Unable to generate bindings");
+
+    bindings
+        .write_to_file("src/ffi.rs")
+        .expect("Couldn't write bindings to ffi.rs");
+}
+
 fn setup_build(build: &mut cc::Build, include_dir: &PathBuf) {
     build.include(include_dir);
     build.define("NDEBUG", Some("1"));