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use crate::parse::GpuStructConfig;
use syn::ItemStruct;
pub fn validate_repr(item_struct: &ItemStruct, config: &GpuStructConfig) -> Result<(), syn::Error> {
for attr in &item_struct.attrs {
if !attr.path().is_ident("repr") {
continue;
}
let Ok(nested) = attr.parse_args_with(|input: syn::parse::ParseStream<'_>| {
let mut tokens = Vec::new();
while !input.is_empty() {
let tt: proc_macro2::TokenTree = input.parse()?;
tokens.push(tt);
}
Ok(tokens)
}) else {
continue;
};
for tt in &nested {
if let proc_macro2::TokenTree::Ident(ident) = tt {
if ident == "packed" {
return Err(syn::Error::new(
ident.span(),
"#[repr(packed)] is incompatible with #[gpu_struct]; \
GPU structs require natural alignment for correct memory layout",
));
}
if ident == "align" {
if let Some(config_align) = config.align {
let tokens_str = nested
.iter()
.map(|t| t.to_string())
.collect::<String>();
if let Some(paren_start) = tokens_str.find('(') {
if let Some(paren_end) = tokens_str.find(')') {
let val_str = &tokens_str[paren_start + 1..paren_end];
if let Ok(existing_align) = val_str.trim().parse::<usize>() {
if existing_align != config_align {
return Err(syn::Error::new(
ident.span(),
format!(
"conflicting alignment: \
#[repr(C, align({existing_align}))] conflicts \
with align = {config_align}; \
remove the existing repr or adjust align"
),
));
}
}
}
}
}
}
}
}
}
Ok(())
}