Include struct layout in callbacks.

bindgen-tests/tests/parse_callbacks/item_discovery_callback/mod.rs

@@ -4,7 +4,9 @@ use std::rc::Rc;
 
 use regex::Regex;
 
-use bindgen::callbacks::{DiscoveredItem, DiscoveredItemId, ParseCallbacks};
+use bindgen::callbacks::{
+    DiscoveredItem, DiscoveredItemId, Layout, ParseCallbacks,
+};
 use bindgen::Builder;
 
 #[derive(Debug, Default)]
@@ -37,6 +39,11 @@ pub fn test_item_discovery_callback() {
             DiscoveredItem::Struct {
                 original_name: Some("NamedStruct".to_string()),
                 final_name: "NamedStruct".to_string(),
+                layout: Some(Layout {
+                    size: 0,
+                    align: 1,
+                    packed: false,
+                }),
             },
         ),
         (
@@ -78,6 +85,11 @@ pub fn test_item_discovery_callback() {
             DiscoveredItem::Struct {
                 original_name: None,
                 final_name: "_bindgen_ty_*".to_string(),
+                layout: Some(Layout {
+                    size: 0,
+                    align: 1,
+                    packed: false,
+                }),
             },
         ),
         (
@@ -160,6 +172,7 @@ pub fn compare_struct_info(
     let DiscoveredItem::Struct {
         original_name: expected_original_name,
         final_name: expected_final_name,
+        layout: expected_layout,
     } = expected_item
     else {
         unreachable!()
@@ -168,6 +181,7 @@ pub fn compare_struct_info(
     let DiscoveredItem::Struct {
         original_name: generated_original_name,
         final_name: generated_final_name,
+        layout: generated_layout,
     } = generated_item
     else {
         unreachable!()
@@ -177,12 +191,22 @@ pub fn compare_struct_info(
         return false;
     }
 
-    match (expected_original_name, generated_original_name) {
+    if !match (expected_original_name, generated_original_name) {
         (None, None) => true,
         (Some(expected_original_name), Some(generated_original_name)) => {
             compare_names(expected_original_name, generated_original_name)
         }
         _ => false,
+    } {
+        return false;
+    }
+
+    match (expected_layout, generated_layout) {
+        (None, None) => true,
+        (Some(expected_layout), Some(actual_layout)) => {
+            expected_layout == actual_layout
+        }
+        _ => false,
     }
 }
 

bindgen/callbacks.rs

@@ -4,6 +4,7 @@ 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 crate::ir::layout::Layout;
 use std::fmt;
 
 /// An enum to allow ignoring parsing of macros.
@@ -192,6 +193,10 @@ pub enum DiscoveredItem {
 
         /// The name of the generated binding
         final_name: String,
+
+        /// The layout of the structure in memory (size, alignment, etc.) if
+        /// known.
+        layout: Option<Layout>,
     },
 
     /// Represents a union with its original name in C and its generated binding name

bindgen/codegen/mod.rs

@@ -2490,6 +2490,7 @@ impl CodeGenerator for CompInfo {
                         .name()
                         .map(String::from),
                     final_name: canonical_ident.to_string(),
+                    layout,
                 },
                 CompKind::Union => DiscoveredItem::Union {
                     original_name: item

bindgen/ir/layout.rs

@@ -7,14 +7,14 @@ use crate::ir::context::BindgenContext;
 use std::cmp;
 
 /// A type that represents the struct layout of a type.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) struct Layout {
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
+pub struct Layout {
     /// The size (in bytes) of this layout.
-    pub(crate) size: usize,
+    pub size: usize,
     /// The alignment (in bytes) of this layout.
-    pub(crate) align: usize,
+    pub align: usize,
     /// Whether this layout's members are packed or not.
-    pub(crate) packed: bool,
+    pub packed: bool,
 }
 
 #[test]