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Better error message for #[agb::entry] errors

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This commit is contained in:
Gwilym Inzani 2023-03-23 23:10:50 +00:00
parent 3793034ec3
commit 52e9e3eb32
1 changed files with 58 additions and 33 deletions
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91
agb-macros/src/lib.rs
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@ -8,56 +8,82 @@ use syn::{FnArg, Ident, ItemFn, Pat, ReturnType, Token, Type, Visibility};
use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};
fn token_stream_with_string_error(mut tokens: TokenStream, error_str: &str) -> TokenStream {
tokens.extend(TokenStream::from(quote! { compile_error!(#error_str); }));
tokens
}
#[proc_macro_attribute]
pub fn entry(args: TokenStream, input: TokenStream) -> TokenStream {
let f: ItemFn = syn::parse(input).expect("#[agb::entry] must be applied to a function");
let f: ItemFn = match syn::parse(input.clone()) {
Ok(it) => it,
Err(_) => return input,
};
// Check that the function signature is correct
assert!(
f.sig.constness.is_none()
&& f.vis == Visibility::Inherited
&& f.sig.abi.is_none()
&& f.sig.generics.params.is_empty()
&& f.sig.generics.where_clause.is_none()
&& match f.sig.output {
ReturnType::Type(_, ref ty) => matches!(**ty, Type::Never(_)),
_ => false,
},
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !"
);
if !(f.sig.constness.is_none()
&& f.vis == Visibility::Inherited
&& f.sig.abi.is_none()
&& f.sig.generics.params.is_empty()
&& f.sig.generics.where_clause.is_none()
&& match f.sig.output {
ReturnType::Type(_, ref ty) => matches!(**ty, Type::Never(_)),
_ => false,
})
{
return token_stream_with_string_error(
input,
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !",
);
}
// Check that the function signature takes 1 argument, agb::Gba
let arguments: Vec<_> = f.sig.inputs.iter().collect();
assert_eq!(
arguments.len(),
1,
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !, but got {} arguments",
arguments.len(),
);
if arguments.len() != 1 {
return token_stream_with_string_error(
input,
&format!(
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !, but got {} arguments",
arguments.len()
)
);
}
let (argument_type, (argument_name, is_mutable)) = match arguments[0] {
FnArg::Typed(pat_type) => (
pat_type.ty.to_token_stream(),
match &*pat_type.pat {
Pat::Ident(ident) => {
assert!(
ident.attrs.is_empty() && ident.by_ref.is_none() && ident.subpat.is_none(),
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !"
);
if !(ident.attrs.is_empty() && ident.by_ref.is_none() && ident.subpat.is_none())
{
return token_stream_with_string_error(
input,
"#[agb::entry] must have signature [unsafe] fn (mut agb::Gba) -> !",
);
}
(ident.ident.clone(), ident.mutability.is_some())
}
_ => panic!("Expected first argument to #[agb::entry] to be a basic identifier"),
_ => {
return token_stream_with_string_error(
input,
"Expected first argument to #[agb::entry] to be a basic identifier",
)
}
},
),
_ => panic!("Expected first argument to #[agb::entry] to not be self"),
_ => {
return token_stream_with_string_error(
input,
"Expected first argument to #[agb::entry] to not be self",
)
}
};
assert!(
args.to_string() == "",
"Must pass no args to #[agb::entry] macro"
);
if args.to_string() != "" {
return token_stream_with_string_error(input, "Must pass no args to #[agb::entry] macro");
}
let fn_name = hashed_ident(&f);
@ -70,10 +96,9 @@ pub fn entry(args: TokenStream, input: TokenStream) -> TokenStream {
None
};
assert!(
argument_type.to_string().ends_with("Gba"),
"Expected first argument to have type 'Gba'"
);
if !argument_type.to_string().ends_with("Gba") {
return token_stream_with_string_error(input, "Expected first argument to have type 'Gba'");
}
quote!(
#[cfg(not(test))]