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fix(macros): only take an integer type from repr in the Type derive #4403

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fix(macros): only take an integer type from repr in the Type derive #4403

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24 changes: 22 additions & 2 deletions sqlx-macros-core/src/derives/attributes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -127,8 +127,28 @@ pub fn parse_container_attributes(input: &[Attribute]) -> syn::Result<SqlxContai
let list: Punctuated<Meta, Token![,]> =
attr.parse_args_with(<Punctuated<Meta, Token![,]>>::parse_terminated)?;

if let Some(path) = list.iter().find_map(|f| f.require_path_only().ok()) {
try_set!(repr, path.get_ident().unwrap().clone(), list);
// only an integer type is a usable repr; `C`, `transparent` etc. are not
if let Some(ident) = list
.iter()
.filter_map(|f| f.require_path_only().ok()?.get_ident())
.find(|ident| {
matches!(
ident.to_string().as_str(),
"i8" | "i16"
| "i32"
| "i64"
| "i128"
| "isize"
| "u8"
| "u16"
| "u32"
| "u64"
| "u128"
| "usize"
)
})
{
try_set!(repr, ident.clone(), list);
}
}
}
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23 changes: 23 additions & 0 deletions tests/sqlite/derives.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,19 @@ test_type!(origin_enum<Origin>(Sqlite,
"2" == Origin::Bar,
));

// A `repr` without an integer type does not make a weak enum
#[derive(Debug, PartialEq, sqlx::Type)]
#[repr(C)]

@abonander abonander Sep 9, 2026 •
edited
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I think I would prefer to forbid #[repr(C)] because it's ambiguous what the enum should map to.

This test assumes these enums should map to a string. However, some users may actually expect us to apply the C-like enum rules and map this to an integer. I don't think that's particularly unreasonable, actually. The real problem is that the actual integer type is defined per-target, so we'd have to encode all those rules and validate them. But then you'd potentially get a different type on various platforms when you're presumably trying to map that to the same schema type.

That's a lot of technical debt for a rather niche feature.

@abonander abonander Sep 9, 2026

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Since it didn't even compile before, forbidding #[repr(C)] is a backwards compatible change.

enum ReprC {
Foo,
Bar,
}

test_type!(repr_c_enum<ReprC>(Sqlite,
"'Foo'" == ReprC::Foo,
"'Bar'" == ReprC::Bar,
));

#[derive(PartialEq, Eq, Debug, sqlx::Type)]
#[sqlx(transparent)]
struct TransparentTuple(i64);
Expand All @@ -32,3 +45,13 @@ test_type!(transparent_named<TransparentNamed>(Sqlite,
"0" == TransparentNamed { field: 0 },
"23523" == TransparentNamed { field: 23523 },
));

#[derive(PartialEq, Eq, Debug, sqlx::Type)]
#[sqlx(transparent)]
#[repr(transparent)]
struct TransparentRepr(i64);

test_type!(transparent_repr<TransparentRepr>(Sqlite,
"0" == TransparentRepr(0),
"23523" == TransparentRepr(23523)
));
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