Vendor things

third-party/vendor/bindgen/codegen/postprocessing/mod.rs

@@ -0,0 +1,66 @@
+use proc_macro2::TokenStream;
+use quote::ToTokens;
+use syn::{parse2, ItemMod};
+
+use crate::BindgenOptions;
+
+mod merge_extern_blocks;
+mod sort_semantically;
+
+use merge_extern_blocks::merge_extern_blocks;
+use sort_semantically::sort_semantically;
+
+struct PostProcessingPass {
+    should_run: fn(&BindgenOptions) -> bool,
+    run: fn(&mut ItemMod),
+}
+
+// TODO: This can be a const fn when mutable references are allowed in const
+// context.
+macro_rules! pass {
+    ($pass:ident) => {
+        PostProcessingPass {
+            should_run: |options| options.$pass,
+            run: |item_mod| $pass(item_mod),
+        }
+    };
+}
+
+const PASSES: &[PostProcessingPass] =
+    &[pass!(merge_extern_blocks), pass!(sort_semantically)];
+
+pub(crate) fn postprocessing(
+    items: Vec<TokenStream>,
+    options: &BindgenOptions,
+) -> TokenStream {
+    let require_syn = PASSES.iter().any(|pass| (pass.should_run)(options));
+    if !require_syn {
+        return items.into_iter().collect();
+    }
+    let module_wrapped_tokens =
+        quote!(mod wrapper_for_postprocessing_hack { #( #items )* });
+
+    // This syn business is a hack, for now. This means that we are re-parsing already
+    // generated code using `syn` (as opposed to `quote`) because `syn` provides us more
+    // control over the elements.
+    // One caveat is that some of the items coming from `quote`d output might have
+    // multiple items within them. Hence, we have to wrap the incoming in a `mod`.
+    // The `unwrap` here is deliberate because bindgen should generate valid rust items at all
+    // times.
+    let mut item_mod = parse2::<ItemMod>(module_wrapped_tokens).unwrap();
+
+    for pass in PASSES {
+        if (pass.should_run)(options) {
+            (pass.run)(&mut item_mod);
+        }
+    }
+
+    let synful_items = item_mod
+        .content
+        .map(|(_, items)| items)
+        .unwrap_or_default()
+        .into_iter()
+        .map(|item| item.into_token_stream());
+
+    quote! { #( #synful_items )* }
+}