add option to remove type aliases

bindgen-cli/options.rs

@@ -568,6 +568,12 @@ where
             Arg::new("merge-extern-blocks")
                 .long("merge-extern-blocks")
                 .help("Deduplicates extern blocks."),
+            Arg::new("remove-alias")
+                .long("remove-alias")
+                .help("Remove type aliases matching <regex>.")
+                .value_name("regex")
+                .multiple_occurrences(true)
+                .number_of_values(1),
             Arg::new("V")
                 .long("version")
                 .help("Prints the version, and exits"),
@@ -1088,5 +1094,11 @@ where
         builder = builder.merge_extern_blocks(true);
     }
 
+    if let Some(remove_alias) = matches.values_of("remove-alias") {
+        for regex in remove_alias {
+            builder = builder.remove_alias(regex);
+        }
+    }
+
     Ok((builder, output, verbose))
 }

bindgen-tests/tests/headers/remove_alias.h

@@ -0,0 +1,14 @@
+// bindgen-flags: --remove-alias "int.*"
+
+typedef long long int64;
+typedef int int32;
+typedef int32 i32;
+
+struct int32_ {
+    int32 inner;
+};
+
+int64 foo();
+int32 bar();
+i32 baz();
+struct int32_ qux();

bindgen-tests/tests/headers/remove_template_alias.hpp

@@ -0,0 +1,4 @@
+// bindgen-flags: --remove-alias "Wrapped"
+
+template<typename T>
+using Wrapped = T;

bindgen/codegen/postprocessing/merge_extern_blocks.rs

@@ -3,7 +3,13 @@ use syn::{
     Item, ItemForeignMod, ItemMod,
 };
 
-pub(super) fn merge_extern_blocks(item_mod: &mut ItemMod) {
+use crate::BindgenOptions;
+
+#[inline]
+pub(super) fn merge_extern_blocks(
+    item_mod: &mut ItemMod,
+    _options: &BindgenOptions,
+) {
     Visitor.visit_item_mod_mut(item_mod)
 }
 

bindgen/codegen/postprocessing/mod.rs

@@ -5,29 +5,37 @@ use syn::{parse2, ItemMod};
 use crate::BindgenOptions;
 
 mod merge_extern_blocks;
+mod remove_alias;
 mod sort_semantically;
 
 use merge_extern_blocks::merge_extern_blocks;
+use remove_alias::remove_alias;
 use sort_semantically::sort_semantically;
 
 struct PostProcessingPass {
     should_run: fn(&BindgenOptions) -> bool,
-    run: fn(&mut ItemMod),
+    run: fn(&mut ItemMod, &BindgenOptions),
 }
 
 // TODO: This can be a const fn when mutable references are allowed in const
 // context.
 macro_rules! pass {
     ($pass:ident) => {
+        pass!($pass, |options| options.$pass)
+    };
+    ($pass:ident, $should_run:expr) => {
         PostProcessingPass {
-            should_run: |options| options.$pass,
-            run: |item_mod| $pass(item_mod),
+            should_run: $should_run,
+            run: |item_mod, options| $pass(item_mod, options),
         }
     };
 }
 
-const PASSES: &[PostProcessingPass] =
-    &[pass!(merge_extern_blocks), pass!(sort_semantically)];
+const PASSES: &[PostProcessingPass] = &[
+    pass!(merge_extern_blocks),
+    pass!(sort_semantically),
+    pass!(remove_alias, |options| !options.remove_alias.is_empty()),
+];
 
 pub(crate) fn postprocessing(
     items: Vec<TokenStream>,
@@ -51,7 +59,7 @@ pub(crate) fn postprocessing(
 
     for pass in PASSES {
         if (pass.should_run)(options) {
-            (pass.run)(&mut item_mod);
+            (pass.run)(&mut item_mod, options);
         }
     }
 

bindgen/codegen/postprocessing/remove_alias.rs

@@ -0,0 +1,55 @@
+use syn::visit_mut::{visit_type_mut, VisitMut};
+use syn::{Item, ItemMod, Type};
+
+use crate::BindgenOptions;
+
+pub(super) fn remove_alias(item_mod: &mut ItemMod, options: &BindgenOptions) {
+    if let Some((_, items)) = item_mod.content.as_mut() {
+        let visitors: Vec<_> = items
+            .iter()
+            .enumerate()
+            .rev()
+            .filter_map(|(index, item)| {
+                if let Item::Type(alias_item) = item {
+                    if alias_item.generics.params.is_empty() {
+                        let ident = alias_item.ident.to_string();
+                        if options.remove_alias.matches(&ident) {
+                            return Some((
+                                index,
+                                Visitor {
+                                    ident,
+                                    ty: alias_item.ty.clone(),
+                                },
+                            ));
+                        }
+                    }
+                }
+                None
+            })
+            .collect();
+
+        for (index, mut visitor) in visitors {
+            items.remove(index);
+            for item in items.iter_mut() {
+                visitor.visit_item_mut(item);
+            }
+        }
+    }
+}
+
+struct Visitor {
+    ident: String,
+    ty: Box<Type>,
+}
+
+impl VisitMut for Visitor {
+    fn visit_type_mut(&mut self, ty: &mut Type) {
+        if let Type::Path(type_path) = ty {
+            if type_path.path.is_ident(&self.ident) {
+                *ty = self.ty.as_ref().clone();
+            }
+        }
+
+        visit_type_mut::<_>(self, ty)
+    }
+}

bindgen/codegen/postprocessing/sort_semantically.rs

@@ -3,7 +3,13 @@ use syn::{
     Item, ItemMod,
 };
 
-pub(super) fn sort_semantically(item_mod: &mut ItemMod) {
+use crate::BindgenOptions;
+
+#[inline]
+pub(super) fn sort_semantically(
+    item_mod: &mut ItemMod,
+    _options: &BindgenOptions,
+) {
     Visitor.visit_item_mod_mut(item_mod)
 }
 

bindgen/lib.rs

@@ -358,6 +358,7 @@ impl Builder {
             (&self.options.no_default_types, "--no-default"),
             (&self.options.no_hash_types, "--no-hash"),
             (&self.options.must_use_types, "--must-use-type"),
+            (&self.options.remove_alias, "--remove-alias"),
         ];
 
         for (set, flag) in regex_sets {
@@ -1770,6 +1771,13 @@ impl Builder {
         self.options.c_naming = doit;
         self
     }
+
+    /// Remove a type alias that matches the provided argument. Regular
+    /// expressions are supported.
+    pub fn remove_alias<T: Into<String>>(mut self, arg: T) -> Self {
+        self.options.remove_alias.insert(arg.into());
+        self
+    }
 }
 
 /// Configuration options for generated bindings.
@@ -2105,6 +2113,9 @@ struct BindgenOptions {
 
     /// Deduplicate `extern` blocks.
     merge_extern_blocks: bool,
+
+    /// The set of type aliases that should be removed.
+    remove_alias: RegexSet,
 }
 
 /// TODO(emilio): This is sort of a lie (see the error message that results from
@@ -2142,6 +2153,7 @@ impl BindgenOptions {
             &mut self.no_default_types,
             &mut self.no_hash_types,
             &mut self.must_use_types,
+            &mut self.remove_alias,
         ];
         let record_matches = self.record_matches;
         for regex_set in &mut regex_sets {
@@ -2261,6 +2273,7 @@ impl Default for BindgenOptions {
             vtable_generation: false,
             sort_semantically: false,
             merge_extern_blocks: false,
+            remove_alias: Default::default(),
         }
     }
 }