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[Feature] std::panic::Location support #291

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[Feature] std::panic::Location support #291

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f5735bd
implement #[location] attr and location field for enums
onlycs Mar 5, 2024
43eddc2
impl for structs
onlycs Mar 6, 2024
bcd35d7
do not require location attr
onlycs Mar 6, 2024
7d8dae2
update "deriving From..." message to include location
onlycs Mar 6, 2024
96702c7
Merge pull request #1 from dtolnay/master
onlycs Apr 10, 2024
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8 changes: 8 additions & 0 deletions impl/src/attr.rs
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Expand Up @@ -12,6 +12,7 @@ pub struct Attrs<'a> {
pub display: Option<Display<'a>>,
pub source: Option<&'a Attribute>,
pub backtrace: Option<&'a Attribute>,
pub location: Option<&'a Attribute>,
pub from: Option<&'a Attribute>,
pub transparent: Option<Transparent<'a>>,
}
Expand Down Expand Up @@ -50,6 +51,7 @@ pub fn get(input: &[Attribute]) -> Result<Attrs> {
display: None,
source: None,
backtrace: None,
location: None,
from: None,
transparent: None,
};
Expand All @@ -69,6 +71,12 @@ pub fn get(input: &[Attribute]) -> Result<Attrs> {
return Err(Error::new_spanned(attr, "duplicate #[backtrace] attribute"));
}
attrs.backtrace = Some(attr);
} else if attr.path().is_ident("location") {
attr.meta.require_path_only()?;
if attrs.location.is_some() {
return Err(Error::new_spanned(attr, "duplicate #[location] attribute"));
}
attrs.location = Some(attr);
} else if attr.path().is_ident("from") {
match attr.meta {
Meta::Path(_) => {}
Expand Down
179 changes: 118 additions & 61 deletions impl/src/expand.rs
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Expand Up @@ -124,10 +124,28 @@ fn impl_struct(input: Struct) -> TokenStream {
#request.provide_ref::<std::backtrace::Backtrace>(&self.#backtrace);
})
};
let location_provide = if let Some(location_field) = input.location_field() {
let location = &location_field.member;

if type_is_option(location_field.ty) {
Some(quote! {
if let ::core::option::Option::Some(location) = &self.#location {
#request.provide_ref::<::core::panic::Location>(location);
}
})
} else {
Some(quote! {
#request.provide_ref::<::core::panic::Location>(&self.#location);
})
}
} else {
None
};
quote! {
use thiserror::__private::ThiserrorProvide as _;
#source_provide
#self_provide
#location_provide
}
} else if type_is_option(backtrace_field.ty) {
quote! {
Expand Down Expand Up @@ -190,11 +208,14 @@ fn impl_struct(input: Struct) -> TokenStream {
let from_impl = input.from_field().map(|from_field| {
let backtrace_field = input.distinct_backtrace_field();
let from = unoptional_type(from_field.ty);
let body = from_initializer(from_field, backtrace_field);
let body = from_initializer(from_field, backtrace_field, input.location_field());
let track_caller = input.location_field().map(|_| quote!(#[track_caller]));

quote! {
#[allow(unused_qualifications)]
impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
#[allow(deprecated)]
#track_caller
fn from(source: #from) -> Self {
#ty #body
}
Expand Down Expand Up @@ -281,25 +302,43 @@ fn impl_enum(input: Enum) -> TokenStream {
let request = quote!(request);
let arms = input.variants.iter().map(|variant| {
let ident = &variant.ident;
match (variant.backtrace_field(), variant.source_field()) {
(Some(backtrace_field), Some(source_field))
if backtrace_field.attrs.backtrace.is_none() =>
{
let backtrace = &backtrace_field.member;
let source = &source_field.member;
let varsource = quote!(source);
let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {source.member_span()=>
if let ::core::option::Option::Some(source) = #varsource {
source.thiserror_provide(#request);
}
}

let mut arm = vec![];
let mut head = vec![];

if let Some((source_field, backtrace_field)) = variant
.backtrace_field()
.and_then(|b| variant.source_field().take().map(|s| (s, b)))
.and_then(|(s, b)| {
// TODO: replace with take_if upon stabilization

if s.member == b.member {
Some((s, b))
} else {
quote_spanned! {source.member_span()=>
#varsource.thiserror_provide(#request);
None
}
})
{
let backtrace = &backtrace_field.member;
let varsource = quote!(source);
let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {backtrace.member_span()=>
if let ::core::option::Option::Some(source) = #varsource {
source.thiserror_provide(#request);
}
};
let self_provide = if type_is_option(backtrace_field.ty) {
}
} else {
quote_spanned! {backtrace.member_span()=>
#varsource.thiserror_provide(#request);
}
};

head.push(quote! { #backtrace: #varsource });
arm.push(quote! { #source_provide });
} else {
if let Some(backtrace_field) = variant.backtrace_field() {
let backtrace = &backtrace_field.member;
let body = if type_is_option(backtrace_field.ty) {
quote! {
if let ::core::option::Option::Some(backtrace) = backtrace {
#request.provide_ref::<std::backtrace::Backtrace>(backtrace);
Expand All @@ -310,68 +349,64 @@ fn impl_enum(input: Enum) -> TokenStream {
#request.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
};
quote! {
#ty::#ident {
#backtrace: backtrace,
#source: #varsource,
..
} => {
use thiserror::__private::ThiserrorProvide as _;
#source_provide
#self_provide
}
}

head.push(quote! { #backtrace: backtrace });
arm.push(quote! { #body });
}
(Some(backtrace_field), Some(source_field))
if backtrace_field.member == source_field.member =>
{
let backtrace = &backtrace_field.member;

if let Some(source_field) = variant.source_field() {
let source = &source_field.member;
let varsource = quote!(source);

let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {backtrace.member_span()=>
quote_spanned! {source.member_span()=>
if let ::core::option::Option::Some(source) = #varsource {
source.thiserror_provide(#request);
}
}
} else {
quote_spanned! {backtrace.member_span()=>
quote_spanned! {source.member_span()=>
#varsource.thiserror_provide(#request);
}
};

head.push(quote! { #source: #varsource });
arm.push(quote! { #source_provide });
}
}

if let Some(location_field) = variant.location_field() {
let location = &location_field.member;

let location_provide = if type_is_option(location_field.ty) {
quote! {
#ty::#ident {#backtrace: #varsource, ..} => {
use thiserror::__private::ThiserrorProvide as _;
#source_provide
if let ::core::option::Option::Some(location) = location {
#request.provide_ref::<::core::panic::Location>(location);
}
}
}
(Some(backtrace_field), _) => {
let backtrace = &backtrace_field.member;
let body = if type_is_option(backtrace_field.ty) {
quote! {
if let ::core::option::Option::Some(backtrace) = backtrace {
#request.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
}
} else {
quote! {
#request.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
};
} else {
quote! {
#ty::#ident {#backtrace: backtrace, ..} => {
#body
}
#request.provide_ref::<::core::panic::Location>(location);
}
};

head.push(quote! { #location: location });
arm.push(quote! { #location_provide });
}

quote! {
#ty::#ident {
#(#head,)*
..
} => {
use thiserror::__private::ThiserrorProvide as _;
#(#arm)*
}
(None, _) => quote! {
#ty::#ident {..} => {}
},
}
});
Some(quote! {
fn provide<'_request>(&'_request self, #request: &mut std::error::Request<'_request>) {
#[allow(deprecated)]
#[allow(deprecated, unused_imports)]
match self {
#(#arms)*
}
Expand Down Expand Up @@ -444,13 +479,17 @@ fn impl_enum(input: Enum) -> TokenStream {
let from_impls = input.variants.iter().filter_map(|variant| {
let from_field = variant.from_field()?;
let backtrace_field = variant.distinct_backtrace_field();
let location_field = variant.location_field();
let variant = &variant.ident;
let from = unoptional_type(from_field.ty);
let body = from_initializer(from_field, backtrace_field);
let body = from_initializer(from_field, backtrace_field, location_field);
let track_caller = location_field.map(|_| quote!(#[track_caller]));

Some(quote! {
#[allow(unused_qualifications)]
impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause {
#[allow(deprecated)]
#track_caller
fn from(source: #from) -> Self {
#ty::#variant #body
}
Expand Down Expand Up @@ -501,7 +540,11 @@ fn use_as_display(needs_as_display: bool) -> Option<TokenStream> {
}
}

fn from_initializer(from_field: &Field, backtrace_field: Option<&Field>) -> TokenStream {
fn from_initializer(
from_field: &Field,
backtrace_field: Option<&Field>,
location_field: Option<&Field>,
) -> TokenStream {
let from_member = &from_field.member;
let some_source = if type_is_option(from_field.ty) {
quote!(::core::option::Option::Some(source))
Expand All @@ -520,9 +563,23 @@ fn from_initializer(from_field: &Field, backtrace_field: Option<&Field>) -> Toke
}
}
});
let location = location_field.map(|location_field| {
let location_member = &location_field.member;

if type_is_option(location_field.ty) {
quote! {
#location_member: ::core::option::Option::Some(::core::panic::Location::caller()),
}
} else {
quote! {
#location_member: ::core::convert::From::from(::core::panic::Location::caller()),
}
}
});
quote!({
#from_member: #some_source,
#backtrace
#location
})
}

Expand Down
2 changes: 1 addition & 1 deletion impl/src/lib.rs
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Expand Up @@ -29,7 +29,7 @@ mod valid;
use proc_macro::TokenStream;
use syn::{parse_macro_input, DeriveInput};

#[proc_macro_derive(Error, attributes(backtrace, error, from, source))]
#[proc_macro_derive(Error, attributes(backtrace, error, from, source, location))]
pub fn derive_error(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
expand::derive(&input).into()
Expand Down