codegen: Properly track alignment of unions.

This makes us not unnecessarily add repr(align) to unions.

Closes #1498.

Author: emilio

CHANGELOG.md

@@ -9,53 +9,56 @@
   - [Removed](#removed)
   - [Fixed](#fixed)
   - [Security](#security)
-- [0.47.3](#0473)
+- [0.48.0](#0480)
   - [Changed](#changed-1)
-- [0.47.2](#0472)
   - [Fixed](#fixed-1)
-- [0.47.1](#0471)
+- [0.47.3](#0473)
   - [Changed](#changed-2)
+- [0.47.2](#0472)
   - [Fixed](#fixed-2)
-- [0.47.0](#0470)
+- [0.47.1](#0471)
   - [Changed](#changed-3)
   - [Fixed](#fixed-3)
+- [0.47.0](#0470)
+  - [Changed](#changed-4)
+  - [Fixed](#fixed-4)
 - [0.33.1 .. 0.46.0](#0331--0460)
   - [Added](#added-1)
   - [Removed](#removed-1)
-  - [Changed](#changed-4)
-  - [Fixed](#fixed-4)
-- [0.33.1](#0331)
+  - [Changed](#changed-5)
   - [Fixed](#fixed-5)
+- [0.33.1](#0331)
+  - [Fixed](#fixed-6)
 - [0.33.0](#0330)
   - [Added](#added-2)
-  - [Changed](#changed-5)
+  - [Changed](#changed-6)
   - [Deprecated](#deprecated-1)
   - [Removed](#removed-2)
-  - [Fixed](#fixed-6)
+  - [Fixed](#fixed-7)
   - [Security](#security-1)
 - [0.32.2](#0322)
-  - [Fixed](#fixed-7)
-- [0.32.1](#0321)
   - [Fixed](#fixed-8)
+- [0.32.1](#0321)
+  - [Fixed](#fixed-9)
 - [0.32.0](#0320)
   - [Added](#added-3)
-  - [Changed](#changed-6)
-  - [Fixed](#fixed-9)
+  - [Changed](#changed-7)
+  - [Fixed](#fixed-10)
 - [0.31.0](#0310)
   - [Added](#added-4)
-  - [Changed](#changed-7)
+  - [Changed](#changed-8)
   - [Deprecated](#deprecated-2)
   - [Removed](#removed-3)
-  - [Fixed](#fixed-10)
+  - [Fixed](#fixed-11)
 - [0.30.0](#0300)
   - [Added](#added-5)
-  - [Changed](#changed-8)
+  - [Changed](#changed-9)
   - [Deprecated](#deprecated-3)
-  - [Fixed](#fixed-11)
+  - [Fixed](#fixed-12)
 - [0.29.0](#0290)
   - [Added](#added-6)
-  - [Changed](#changed-9)
-  - [Fixed](#fixed-12)
+  - [Changed](#changed-10)
+  - [Fixed](#fixed-13)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -101,7 +104,12 @@ Released 2019/03/04
 * Default rust target was changed to 1.33, which means that bindgen can get much
   more often the layout of structs right. [#1529][]
 
+## Fixed
+
+* Bindgen will output repr(align) just when needed for unions. [#1498][]
+
 [#1529]: https://github.com/rust-lang-nursery/rust-bindgen/issues/1529
+[#1498]: https://github.com/rust-lang-nursery/rust-bindgen/issues/1498
 
 --------------------------------------------------------------------------------
 

src/codegen/mod.rs

@@ -1589,6 +1589,7 @@ impl CodeGenerator for CompInfo {
             // TODO(emilio): It'd be nice to unify this with the struct path
             // above somehow.
             let layout = layout.expect("Unable to get layout information?");
+            struct_layout.saw_union(layout);
 
             if struct_layout.requires_explicit_align(layout) {
                 explicit_align = Some(layout.align);
@@ -1600,8 +1601,6 @@ impl CodeGenerator for CompInfo {
                     _bindgen_union_align: #ty ,
                 }
             } else {
-                struct_layout.saw_union(layout);
-
                 quote! {
                     pub bindgen_union_field: #ty ,
                 }

src/codegen/struct_layout.rs

@@ -85,9 +85,9 @@ impl<'a> StructLayoutTracker<'a> {
         name: &'a str,
     ) -> Self {
         StructLayoutTracker {
-            name: name,
-            ctx: ctx,
-            comp: comp,
+            name,
+            ctx,
+            comp,
             is_packed: comp.is_packed(ctx, &ty.layout(ctx)),
             latest_offset: 0,
             padding_count: 0,

tests/expectations/tests/16-byte-alignment.rs

@@ -15,7 +15,6 @@ pub struct rte_ipv4_tuple {
     pub __bindgen_anon_1: rte_ipv4_tuple__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union rte_ipv4_tuple__bindgen_ty_1 {
     pub __bindgen_anon_1: rte_ipv4_tuple__bindgen_ty_1__bindgen_ty_1,
@@ -149,7 +148,6 @@ pub struct rte_ipv6_tuple {
     pub __bindgen_anon_1: rte_ipv6_tuple__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union rte_ipv6_tuple__bindgen_ty_1 {
     pub __bindgen_anon_1: rte_ipv6_tuple__bindgen_ty_1__bindgen_ty_1,

tests/expectations/tests/anon_struct_in_union.rs

@@ -13,7 +13,6 @@ pub struct s {
     pub u: s__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union s__bindgen_ty_1 {
     pub field: s__bindgen_ty_1_inner,

tests/expectations/tests/anon_union.rs

@@ -33,7 +33,6 @@ pub struct TErrorResult_DOMExceptionInfo {
     _unused: [u8; 0],
 }
 #[repr(C)]
-#[repr(align(8))]
 pub union TErrorResult__bindgen_ty_1 {
     pub mMessage: *mut TErrorResult_Message,
     pub mDOMExceptionInfo: *mut TErrorResult_DOMExceptionInfo,

tests/expectations/tests/class.rs

@@ -335,7 +335,6 @@ impl Default for IncompleteArrayNonCopiable {
     }
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union Union {
     pub d: f32,

tests/expectations/tests/class_with_inner_struct.rs

@@ -54,7 +54,6 @@ fn bindgen_test_layout_A_Segment() {
     );
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union A__bindgen_ty_1 {
     pub f: ::std::os::raw::c_int,
@@ -89,7 +88,6 @@ impl Default for A__bindgen_ty_1 {
     }
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union A__bindgen_ty_2 {
     pub d: ::std::os::raw::c_int,
@@ -233,7 +231,6 @@ pub struct C {
     pub __bindgen_anon_1: C__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union C__bindgen_ty_1 {
     pub mFunc: C__bindgen_ty_1__bindgen_ty_1,

tests/expectations/tests/derive-debug-mangle-name.rs

@@ -15,7 +15,6 @@ pub struct perf_event_attr {
     pub __bindgen_anon_1: perf_event_attr__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Copy, Clone)]
 pub union perf_event_attr__bindgen_ty_1 {
     pub b: ::std::os::raw::c_int,

tests/expectations/tests/derive-partialeq-anonfield.rs

@@ -14,7 +14,6 @@ pub struct rte_mbuf {
     pub __bindgen_anon_1: rte_mbuf__bindgen_ty_1,
 }
 #[repr(C)]
-#[repr(align(1))]
 #[derive(Copy, Clone)]
 pub union rte_mbuf__bindgen_ty_1 {
     _bindgen_union_align: [u8; 0usize],