Don't traverse through special-cased <stdint.h> types.

src/ir/context.rs

@@ -2250,24 +2250,27 @@ If you encounter an error missing from this list, please file an issue or a PR!"
                         // Sized integer types from <stdint.h> get mapped to Rust primitive
                         // types regardless of whether they are blocklisted, so ensure that
                         // standard traits are considered derivable for them too.
-                        None => match name {
-                            "int8_t" | "uint8_t" | "int16_t" | "uint16_t" |
-                            "int32_t" | "uint32_t" | "int64_t" |
-                            "uint64_t" | "uintptr_t" | "intptr_t" |
-                            "ptrdiff_t" => Some(CanDerive::Yes),
-                            "size_t" if self.options.size_t_is_usize => {
-                                Some(CanDerive::Yes)
-                            }
-                            "ssize_t" if self.options.size_t_is_usize => {
-                                Some(CanDerive::Yes)
-                            }
-                            _ => Some(CanDerive::No),
-                        },
+                        None => Some(if self.is_stdint_type(name) {
+                            CanDerive::Yes
+                        } else {
+                            CanDerive::No
+                        }),
                     })
                     .unwrap_or(CanDerive::No)
             })
     }
 
+    /// Is the given type a type from <stdint.h> that corresponds to a Rust primitive type?
+    pub fn is_stdint_type(&self, name: &str) -> bool {
+        match name {
+            "int8_t" | "uint8_t" | "int16_t" | "uint16_t" | "int32_t" |
+            "uint32_t" | "int64_t" | "uint64_t" | "uintptr_t" |
+            "intptr_t" | "ptrdiff_t" => true,
+            "size_t" | "ssize_t" => self.options.size_t_is_usize,
+            _ => false,
+        }
+    }
+
     /// Get a reference to the set of items we should generate.
     pub fn codegen_items(&self) -> &ItemSet {
         assert!(self.in_codegen_phase());
@@ -2355,7 +2358,10 @@ If you encounter an error missing from this list, please file an issue or a PR!"
                                     TypeKind::Opaque |
                                     TypeKind::TypeParam => return true,
                                     _ => {}
-                                };
+                                }
+                                if self.is_stdint_type(&name) {
+                                    return true;
+                                }
                             }
 
                             // Unnamed top-level enums are special and we

src/ir/ty.rs

@@ -1206,6 +1206,13 @@ impl Trace for Type {
     where
         T: Tracer,
     {
+        if self
+            .name()
+            .map_or(false, |name| context.is_stdint_type(name))
+        {
+            // These types are special-cased in codegen and don't need to be traversed.
+            return;
+        }
         match *self.kind() {
             TypeKind::Pointer(inner) |
             TypeKind::Reference(inner) |

tests/expectations/tests/stdint_typedef.rs

@@ -0,0 +1,41 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+
+extern "C" {
+    pub fn fun() -> u64;
+}
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct Struct {
+    pub field: u64,
+}
+#[test]
+fn bindgen_test_layout_Struct() {
+    const UNINIT: ::std::mem::MaybeUninit<Struct> =
+        ::std::mem::MaybeUninit::uninit();
+    let ptr = UNINIT.as_ptr();
+    assert_eq!(
+        ::std::mem::size_of::<Struct>(),
+        8usize,
+        concat!("Size of: ", stringify!(Struct))
+    );
+    assert_eq!(
+        ::std::mem::align_of::<Struct>(),
+        8usize,
+        concat!("Alignment of ", stringify!(Struct))
+    );
+    assert_eq!(
+        unsafe { ::std::ptr::addr_of!((*ptr).field) as usize - ptr as usize },
+        0usize,
+        concat!(
+            "Offset of field: ",
+            stringify!(Struct),
+            "::",
+            stringify!(field)
+        )
+    );
+}

tests/headers/stdint_typedef.h

@@ -0,0 +1,10 @@
+// bindgen-flags: --allowlist-type="Struct" --allowlist-function="fun"
+
+// no typedef should be emitted for `__uint64_t`
+typedef unsigned long long __uint64_t;
+typedef __uint64_t uint64_t;
+
+uint64_t fun();
+struct Struct {
+	uint64_t field;
+};