[starnix] Update generate.py and remove __bindgen_padding_0

This CL 1) updates the outputs of generate.py so that they match what the script does at ToT (outputs such as arm.rs at ToT haven't been updated/synced), and 2) makes sure fx build works after the update.

Steps:
1. Run `./src/starnix/lib/linux_uapi/generate.py` (no edits)
This results in some changes, notably, io_uring_sqe__bindgen_ty_6 updating to a struct and having 5 params.

2. Run `fx build`. This fails due to:
```
error[E0080]: evaluation of `std::mem::size_of::<io_uring_sqe>` failed
 --> /b/s/w/ir/x/w/fuchsia-third_party-rust/library/core/src/mem/mod.rs:1229:26
  |
  = note: values of the type `[u8; 18446744073709551608]` are too big for the target architecture
```
This is rust-lang/rust-bindgen#3068.

3. Patch in the generate.py edit. Run `./src/starnix/lib/linux_uapi/generate.py` (with edit). Note that generated files now do not have the `pub __bindgen_padding_0` line.

4. `fx build` completes.

Once's qsr's fix at rust-lang/rust-bindgen#3173 is merged and rolled in, we shouldn't need to do the regex replace.

Bug: 398914504
Change-Id: Ic6be5a14f4f00477795588a5ed52e5770c64955e
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1235157
Reviewed-by: Benjamin Lerman <[email protected]>
Commit-Queue: Mary Xia <[email protected]>

Author: maryx

src/starnix/lib/linux_uapi/generate.py

@@ -294,6 +294,8 @@
     (r": StdAtomic([UI])(8|16|32|64)", ": std::sync::atomic::Atomic\\1\\2"),
     # Remove __bindgen_missing from the start of constants defined in missing_includes.h
     (r"const __bindgen_missing_([a-zA-Z_0-9]+)", "const \\1"),
+    # Workaround for https://github.com/rust-lang/rust-bindgen/issues/3068.
+    (r"pub __bindgen_padding_0: \[u8; 1844[0-9]+usize\],\n", ""),
 ]
 
 REPLACEMENTS_PTR = [

src/starnix/lib/linux_uapi/src/arm.rs

@@ -10230,7 +10230,6 @@ impl Default for ff_effect {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct io_uring_sqe {
     pub opcode: __u8,
     pub flags: __u8,
@@ -10365,11 +10364,11 @@ impl Default for io_uring_sqe__bindgen_ty_5 {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
-pub union io_uring_sqe__bindgen_ty_6 {
-    pub __bindgen_anon_1: io_uring_sqe__bindgen_ty_6__bindgen_ty_1,
-    pub optval: __u64,
-    pub cmd: [__u8; 8usize],
+pub struct io_uring_sqe__bindgen_ty_6 {
+    pub __bindgen_anon_1: __BindgenUnionField<io_uring_sqe__bindgen_ty_6__bindgen_ty_1>,
+    pub optval: __BindgenUnionField<__u64>,
+    pub cmd: __BindgenUnionField<[__u8; 0usize]>,
+    pub bindgen_union_field: [u64; 2usize],
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, IntoBytes, FromBytes, KnownLayout, Immutable)]

src/starnix/lib/linux_uapi/src/arm64.rs

@@ -10511,7 +10511,6 @@ impl Default for ff_effect {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct io_uring_sqe {
     pub opcode: __u8,
     pub flags: __u8,
@@ -10646,11 +10645,11 @@ impl Default for io_uring_sqe__bindgen_ty_5 {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
-pub union io_uring_sqe__bindgen_ty_6 {
-    pub __bindgen_anon_1: io_uring_sqe__bindgen_ty_6__bindgen_ty_1,
-    pub optval: __u64,
-    pub cmd: [__u8; 8usize],
+pub struct io_uring_sqe__bindgen_ty_6 {
+    pub __bindgen_anon_1: __BindgenUnionField<io_uring_sqe__bindgen_ty_6__bindgen_ty_1>,
+    pub optval: __BindgenUnionField<__u64>,
+    pub cmd: __BindgenUnionField<[__u8; 0usize]>,
+    pub bindgen_union_field: [u64; 2usize],
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, IntoBytes, FromBytes, KnownLayout, Immutable)]

src/starnix/lib/linux_uapi/src/riscv64.rs

@@ -10445,7 +10445,6 @@ impl Default for ff_effect {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct io_uring_sqe {
     pub opcode: __u8,
     pub flags: __u8,
@@ -10580,11 +10579,11 @@ impl Default for io_uring_sqe__bindgen_ty_5 {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
-pub union io_uring_sqe__bindgen_ty_6 {
-    pub __bindgen_anon_1: io_uring_sqe__bindgen_ty_6__bindgen_ty_1,
-    pub optval: __u64,
-    pub cmd: [__u8; 8usize],
+pub struct io_uring_sqe__bindgen_ty_6 {
+    pub __bindgen_anon_1: __BindgenUnionField<io_uring_sqe__bindgen_ty_6__bindgen_ty_1>,
+    pub optval: __BindgenUnionField<__u64>,
+    pub cmd: __BindgenUnionField<[__u8; 0usize]>,
+    pub bindgen_union_field: [u64; 2usize],
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, IntoBytes, FromBytes, KnownLayout, Immutable)]

src/starnix/lib/linux_uapi/src/x86_64.rs

@@ -10721,7 +10721,6 @@ impl Default for ff_effect {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct io_uring_sqe {
     pub opcode: __u8,
     pub flags: __u8,
@@ -10856,11 +10855,11 @@ impl Default for io_uring_sqe__bindgen_ty_5 {
     }
 }
 #[repr(C)]
-#[derive(Copy, Clone)]
-pub union io_uring_sqe__bindgen_ty_6 {
-    pub __bindgen_anon_1: io_uring_sqe__bindgen_ty_6__bindgen_ty_1,
-    pub optval: __u64,
-    pub cmd: [__u8; 8usize],
+pub struct io_uring_sqe__bindgen_ty_6 {
+    pub __bindgen_anon_1: __BindgenUnionField<io_uring_sqe__bindgen_ty_6__bindgen_ty_1>,
+    pub optval: __BindgenUnionField<__u64>,
+    pub cmd: __BindgenUnionField<[__u8; 0usize]>,
+    pub bindgen_union_field: [u64; 2usize],
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, IntoBytes, FromBytes, KnownLayout, Immutable)]