Add callback to modify contents of macro

Author: igelado

bindgen/callbacks.rs

@@ -4,6 +4,8 @@ pub use crate::ir::analysis::DeriveTrait;
 pub use crate::ir::derive::CanDerive as ImplementsTrait;
 pub use crate::ir::enum_ty::{EnumVariantCustomBehavior, EnumVariantValue};
 pub use crate::ir::int::IntKind;
+pub use cexpr::token::Kind as TokenKind;
+pub use cexpr::token::Token;
 use std::fmt;
 
 /// An enum to allow ignoring parsing of macros.
@@ -49,6 +51,10 @@ pub trait ParseCallbacks: fmt::Debug {
         None
     }
 
+    /// Modify the contents of a macro
+    fn modify_macro(&self, _name: &str, _tokens: &mut Vec<Token>) {
+    }
+
     /// The integer kind an integer macro should have, given a name and the
     /// value of that macro, or `None` if you want the default to be chosen.
     fn int_macro(&self, _name: &str, _value: i64) -> Option<IntKind> {

bindgen/ir/var.rs

@@ -429,6 +429,10 @@ fn parse_macro(
 
     let cexpr_tokens = cursor.cexpr_tokens();
 
+    if let Some(callbacks) = ctx.parse_callbacks() {
+        callbacks.modify_macro(cursor.spelling(), &mut cexpr_tokens);
+    }
+
     let parser = expr::IdentifierParser::new(ctx.parsed_macros());
 
     match parser.macro_definition(&cexpr_tokens) {