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SubjectRe: [PATCH 1/1] rust: macros: fix redefine const_name in `vtable`
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On 8/3/23 4:02 AM, Gary Guo wrote:
> On Wed, 2 Aug 2023 19:50:20 +0000
> Alice Ryhl <aliceryhl@google.com> wrote:
>
>> Qingsong Chen <changxian.cqs@antgroup.com> writes:
>>> let mut body_it = body.stream().into_iter();
>>> - let mut functions = Vec::new();
>>> + let mut functions = HashSet::new();
>>
>> Please use a `BTreeSet` instead of a `HashSet`. A `HashSet` has
>> non-deterministic iteration order, so this will make the macro output
>> different things each time you run it.
>>
>> Alice
>>
>
> Good point.
>
> Another way is to just use the existing `consts` HashSet to avoid
> duplication. Something like
>
> consts.insert(gen_const_name);
>
> after emitting the const item would probably be sufficient.

According to the suggestions of Alice and Gary, we could do the fix
like this:

--- a/rust/macros/vtable.rs
+++ b/rust/macros/vtable.rs
@@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0

use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
-use std::collections::HashSet;
+use std::collections::BTreeSet;
use std::fmt::Write;

pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
@@ -28,7 +28,7 @@ pub(crate) fn vtable(_attr: TokenStream, ts:
TokenStream) -> TokenStream {

let mut body_it = body.stream().into_iter();
let mut functions = Vec::new();
- let mut consts = HashSet::new();
+ let mut consts = BTreeSet::new();
while let Some(token) = body_it.next() {
match token {
TokenTree::Ident(ident) if ident.to_string() == "fn" => {
@@ -74,6 +74,7 @@ pub(crate) fn vtable(_attr: TokenStream, ts:
TokenStream) -> TokenStream {
const {gen_const_name}: bool = false;",
)
.unwrap();
+ consts.insert(gen_const_name);
}
} else {
const_items = "const USE_VTABLE_ATTR: () = ();".to_owned();
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