Name for anonymous enumeration and typedef collide when their layout is different

[therealfrauholle]

Bindgen version 0.69.4 infers name for anonymous enumeration from its typedef, even if the typedef and enumerations are different.

Input C/C++ Header

typedef enum {
    A,
    B
} TypeExport __attribute__((mode(__word__)));

Bindgen Invocation

$ bindgen --default-enum-style rust input.h -o bindings.rs

Actual Results

/* automatically generated by rust-bindgen 0.69.4 */

#[repr(u32)]
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
pub enum TypeExport {
    A = 0,
    B = 1,
}
pub type TypeExport = ::std::os::raw::c_ulong;

Expected Results

/* automatically generated by rust-bindgen 0.69.4 */

#[repr(u32)]
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
pub enum _bindgen_ty_1 {
    A = 0,
    B = 1,
}
pub type TypeExport = ::std::os::raw::c_ulong;

Additional information

I was very confused at first but this makes sense in the end - take this with a grain of salt, my knowledge about C is very limited. It is important to note that

typedef enum Anonymous {
    A,
    B
} TypeExport __attribute__((mode(__word__)));

and

typedef enum Anonymous {
    A,
    B
} __attribute__((mode(__word__))) TypeExport;

appear to be different: In the first case the attribute (__attribute__((mode(__word__))) means "size of the type is a machine word") only applies to the typedef TypeExport, while in the second case the attribute applies directly to enum Anonymous and then transitively to TypeExport. I confirmed that by looking at LLVM output from two different clang versions (windows and ubuntu). See the following example output.

Ubuntu LLVM output

bash $ clang --version
Ubuntu clang version 14.0.0-1ubuntu1.1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
bash $ cat old.c
typedef enum Anonymous {
    A,
    B
} TypeExport __attribute__((mode(__word__)));

void some_function(enum Anonymous anonymous_input, TypeExport typed) {}
bash $ clang -S -emit-llvm old.c && cat old.ll
; ModuleID = 'old.c'
source_filename = "old.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @some_function(i32 noundef %0, i64 noundef %1) #0 {
  %3 = alloca i32, align 4
  %4 = alloca i64, align 8
  store i32 %0, i32* %3, align 4
  store i64 %1, i64* %4, align 8
  ret void
}

attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3, !4}
!llvm.ident = !{!5}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 1}
!4 = !{i32 7, !"frame-pointer", i32 2}
!5 = !{!"Ubuntu clang version 14.0.0-1ubuntu1.1"}
bash $ cat new.c
typedef enum Anonymous {
    A,
    B
} __attribute__((mode(__word__))) TypeExport;

void some_function(enum Anonymous anonymous_input, TypeExport typed) {}
bash $ clang -S -emit-llvm new.c && cat new.ll
; ModuleID = 'new.c'
source_filename = "new.c"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: noinline nounwind optnone uwtable
define dso_local void @some_function(i64 noundef %0, i64 noundef %1) #0 {
  %3 = alloca i64, align 8
  %4 = alloca i64, align 8
  store i64 %0, i64* %3, align 8
  store i64 %1, i64* %4, align 8
  ret void
}

attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3, !4}
!llvm.ident = !{!5}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 1}
!4 = !{i32 7, !"frame-pointer", i32 2}
!5 = !{!"Ubuntu clang version 14.0.0-1ubuntu1.1"}
bash $ 

I would wish that annotating an attribute on the typedef would be forbidded in C and users would have to apply attributes to the enumeration itself, but this appears to be legal so bindgen should be able to handle that correctly.