[Rust] #7659 broke union-typed fields with number in name

[cloneable]

The new flatc 23.1.4 generates broken Rust code when a field with a union type contains a number.

namespace test;

table FieldTable {}

union FieldUnion {
  f :FieldTable (id: 0),
}

table RootTable {
  field42 :FieldUnion (id: 1);
}

root_type RootTable;

This produces references to field_42_type() in the generated code, but the method is correctly called field42_type().

$ grep -i -B3 -A3 field_42_type src/test_generated.rs
        #[inline]
        #[allow(non_snake_case)]
        pub fn field42_as_f(&self) -> Option<FieldTable<'a>> {
            if self.field_42_type() == FieldUnion::f {
                self.field42().map(|t| {
                    // Safety:
                    // Created from a valid Table for this object
--
            use self::flatbuffers::Verifiable;
            v.visit_table(pos)?
                .visit_union::<FieldUnion, _>(
                    "field_42_type",
                    Self::VT_FIELD42_TYPE,
                    "field42",
                    Self::VT_FIELD42,
--
        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
            let mut ds = f.debug_struct("RootTable");
            ds.field("field42_type", &self.field42_type());
            match self.field_42_type() {
                FieldUnion::f => {
                    if let Some(x) = self.field42_as_f() {
                        ds.field("field42", &x)

I pinpointed this to commit a078130 from #7659. flatc built from parent commit produces correct code.

[cloneable]

@CasperN, could you take a look?

[cloneable]

Hi @dbaileychess! You reviewed the change. Could you take a look? Maybe this is an easy fix? This is a regression in the code generator for rust.

[TethysSvensson]

Ping @CasperN @dbaileychess.

[TJKoury]

#7111 Related

[TethysSvensson]

@dbaileychess Since this has been fixed now and v23.5.26 is out, could you also publish that release to crates.io?

[dbaileychess]

@CasperN you do this right?

[CasperN]

yeah, I can do that

Done

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[github-actions]

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