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Made proc-macros panic less

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Replaced the panics in query_group with syn errors for better user feedback and experience
This commit is contained in:
Chase Wilson 2020-07-25 14:38:13 -05:00
parent 380c4c1dc8
commit 78b32d69da
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GPG key ID: 190140C6730EB7E1
1 changed files with 66 additions and 17 deletions
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83
components/salsa-macros/src/query_group.rs
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@ -6,7 +6,8 @@ use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::ToTokens;
use syn::{
parse_macro_input, parse_quote, Attribute, FnArg, Ident, ItemTrait, ReturnType, TraitItem, Type,
parse_macro_input, parse_quote, spanned::Spanned, Attribute, Error, FnArg, Ident, ItemTrait,
ReturnType, TraitItem, Type,
};
/// Implementation for `[salsa::query_group]` decorator.
@ -16,9 +17,15 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
// println!("args: {:#?}", args);
// println!("input: {:#?}", input);
let input_span = input.span();
let (trait_attrs, salsa_attrs) = filter_attrs(input.attrs);
if !salsa_attrs.is_empty() {
panic!("unsupported attributes: {:?}", salsa_attrs);
return Error::new(
input_span,
format!("unsupported attributes: {:?}", salsa_attrs),
)
.to_compile_error()
.into();
}
let trait_vis = input.vis;
@ -43,7 +50,7 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
// Extract attributes.
let (attrs, salsa_attrs) = filter_attrs(method.attrs);
for SalsaAttr { name, tts } in salsa_attrs {
for SalsaAttr { name, tts, span } in salsa_attrs {
match name.as_str() {
"memoized" => {
storage = QueryStorage::Memoized;
@ -74,26 +81,47 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
storage = QueryStorage::Transparent;
num_storages += 1;
}
_ => panic!("unknown salsa attribute `{}`", name),
_ => {
return Error::new(span, format!("unknown salsa attribute `{}`", name))
.to_compile_error()
.into();
}
}
}
// Check attribute combinations.
if num_storages > 1 {
panic!("multiple storage attributes specified");
return Error::new(method.sig.span(), "multiple storage attributes specified")
.to_compile_error()
.into();
}
if invoke.is_some() && storage == QueryStorage::Input {
panic!("#[salsa::invoke] cannot be set on #[salsa::input] queries");
match &invoke {
Some(invoke) if storage == QueryStorage::Input => {
return Error::new(
invoke.span(),
"#[salsa::invoke] cannot be set on #[salsa::input] queries",
)
.to_compile_error()
.into();
}
_ => {}
}
// Extract keys.
let mut iter = method.sig.inputs.iter();
match iter.next() {
Some(FnArg::Receiver(sr)) if sr.mutability.is_none() => (),
_ => panic!(
"first argument of query `{}` must be `&self`",
method.sig.ident
),
_ => {
return Error::new(
method.sig.span(),
format!(
"first argument of query `{}` must be `&self`",
method.sig.ident,
),
)
.to_compile_error()
.into();
}
}
let mut keys: Vec<Type> = vec![];
for arg in iter {
@ -101,17 +129,34 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
FnArg::Typed(ref arg) => {
keys.push((*arg.ty).clone());
}
ref a => panic!("unsupported argument `{:?}` of `{}`", a, method.sig.ident),
ref arg => {
return Error::new(
arg.span(),
format!(
"unsupported argument `{:?}` of `{}`",
arg, method.sig.ident,
),
)
.to_compile_error()
.into();
}
}
}
// Extract value.
let value = match method.sig.output {
ReturnType::Type(_, ref ty) => ty.as_ref().clone(),
ref r => panic!(
"unsupported return type `{:?}` of `{}`",
r, method.sig.ident
),
ref ret => {
return Error::new(
ret.span(),
format!(
"unsupported return type `{:?}` of `{}`",
ret, method.sig.ident
),
)
.to_compile_error()
.into();
}
};
// For `#[salsa::interned]` keys, we create a "lookup key" automatically.
@ -580,6 +625,7 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
struct SalsaAttr {
name: String,
tts: TokenStream,
span: Span,
}
impl std::fmt::Debug for SalsaAttr {
@ -590,14 +636,17 @@ impl std::fmt::Debug for SalsaAttr {
impl TryFrom<syn::Attribute> for SalsaAttr {
type Error = syn::Attribute;
fn try_from(attr: syn::Attribute) -> Result<SalsaAttr, syn::Attribute> {
if is_not_salsa_attr_path(&attr.path) {
return Err(attr);
}
let span = attr.span();
let name = attr.path.segments[1].ident.to_string();
let tts = attr.tokens.into();
Ok(SalsaAttr { name, tts })
Ok(SalsaAttr { name, tts, span })
}
}