ir: Whitelist items that don't generate code to improve derive behavior.

When not whitelisting recursively.

Fixes rust-lang#1454

src/codegen/mod.rs

@@ -610,6 +610,8 @@ impl CodeGenerator for Type {
             TypeKind::TypeParam => {
                 // These items don't need code generation, they only need to be
                 // converted to rust types in fields, arguments, and such.
+                // NOTE(emilio): If you add to this list, make sure to also add
+                // it to BindgenContext::compute_whitelisted_and_codegen_items.
                 return;
             }
             TypeKind::TemplateInstantiation(ref inst) => {

src/ir/context.rs

@@ -2315,6 +2315,28 @@ If you encounter an error missing from this list, please file an issue or a PR!"
                                 return true;
                             }
 
+                            // Auto-whitelist types that don't need code
+                            // generation if not whitelisting recursively, to
+                            // make the #[derive] analysis not be lame.
+                            if !self.options().whitelist_recursively {
+                                match *ty.kind() {
+                                    TypeKind::Void |
+                                    TypeKind::NullPtr |
+                                    TypeKind::Int(..) |
+                                    TypeKind::Float(..) |
+                                    TypeKind::Complex(..) |
+                                    TypeKind::Array(..) |
+                                    TypeKind::Vector(..) |
+                                    TypeKind::Pointer(..) |
+                                    TypeKind::Reference(..) |
+                                    TypeKind::Function(..) |
+                                    TypeKind::ResolvedTypeRef(..) |
+                                    TypeKind::Opaque |
+                                    TypeKind::TypeParam => return true,
+                                    _ => {},
+                                };
+                            }
+
                             // Unnamed top-level enums are special and we
                             // whitelist them via the `whitelisted_vars` filter,
                             // since they're effectively top-level constants,

tests/expectations/tests/issue-1285.rs

@@ -1,12 +1,19 @@
 /* automatically generated by rust-bindgen */
 
-#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
 
 #[repr(C)]
+#[derive(Copy, Clone)]
 pub struct foo {
     pub bar: foo__bindgen_ty_1,
 }
 #[repr(C)]
+#[derive(Copy, Clone)]
 pub union foo__bindgen_ty_1 {
     pub a: ::std::os::raw::c_uint,
     pub b: ::std::os::raw::c_ushort,

tests/expectations/tests/no-recursive-whitelisting.rs

@@ -1,11 +1,16 @@
 /* automatically generated by rust-bindgen */
 
-
-#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
 
 pub enum Bar {}
 
 #[repr(C)]
+#[derive(Debug, Copy, Clone)]
 pub struct Foo {
     pub baz: *mut Bar,
 }