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Expose backtrace via generic member access #182

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merged 3 commits into from Aug 31, 2022
Merged

Expose backtrace via generic member access #182

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985da4c
Expose backtrace via generic member access
dtolnay Aug 31, 2022
986e106
Revert "Disable nightly backtrace testing until converted to provider…
dtolnay Aug 31, 2022
e11c97b
Update backtrace test to provider API
dtolnay Aug 31, 2022
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94 changes: 59 additions & 35 deletions impl/src/expand.rs
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Expand Up @@ -59,45 +59,53 @@ fn impl_struct(input: Struct) -> TokenStream {
}
});

let backtrace_method = input.backtrace_field().map(|backtrace_field| {
let provide_method = input.backtrace_field().map(|backtrace_field| {
let demand = quote!(demand);
let backtrace = &backtrace_field.member;
let body = if let Some(source_field) = input.source_field() {
let source = &source_field.member;
let source_backtrace = if type_is_option(source_field.ty) {
let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {source.span()=>
self.#source.as_ref().and_then(|source| source.as_dyn_error().backtrace())
if let std::option::Option::Some(source) = &self.#source {
source.as_dyn_error().provide(#demand);
}
}
} else {
quote_spanned! {source.span()=>
self.#source.as_dyn_error().backtrace()
self.#source.as_dyn_error().provide(#demand);
}
};
let combinator = if source == backtrace {
source_backtrace
let self_provide = if source == backtrace {
None
} else if type_is_option(backtrace_field.ty) {
quote! {
#source_backtrace.or(self.#backtrace.as_ref())
}
Some(quote! {
if let std::option::Option::Some(backtrace) = &self.#backtrace {
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
})
} else {
quote! {
std::option::Option::Some(#source_backtrace.unwrap_or(&self.#backtrace))
}
Some(quote! {
#demand.provide_ref::<std::backtrace::Backtrace>(&self.#backtrace);
})
};
quote! {
use thiserror::__private::AsDynError;
#combinator
#source_provide
#self_provide
}
} else if type_is_option(backtrace_field.ty) {
quote! {
self.#backtrace.as_ref()
if let std::option::Option::Some(backtrace) = &self.#backtrace {
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
}
} else {
quote! {
std::option::Option::Some(&self.#backtrace)
#demand.provide_ref::<std::backtrace::Backtrace>(&self.#backtrace);
}
};
quote! {
fn backtrace(&self) -> std::option::Option<&std::backtrace::Backtrace> {
fn provide<'_demand>(&'_demand self, #demand: &mut std::any::Demand<'_demand>) {
#body
}
}
Expand Down Expand Up @@ -177,7 +185,7 @@ fn impl_struct(input: Struct) -> TokenStream {
#[allow(unused_qualifications)]
impl #impl_generics #error_trait for #ty #ty_generics #error_where_clause {
#source_method
#backtrace_method
#provide_method
}
#display_impl
#from_impl
Expand Down Expand Up @@ -237,7 +245,8 @@ fn impl_enum(input: Enum) -> TokenStream {
None
};

let backtrace_method = if input.has_backtrace() {
let provide_method = if input.has_backtrace() {
let demand = quote!(demand);
let arms = input.variants.iter().map(|variant| {
let ident = &variant.ident;
match (variant.backtrace_field(), variant.source_field()) {
Expand All @@ -247,22 +256,26 @@ fn impl_enum(input: Enum) -> TokenStream {
let backtrace = &backtrace_field.member;
let source = &source_field.member;
let varsource = quote!(source);
let source_backtrace = if type_is_option(source_field.ty) {
let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {source.span()=>
#varsource.as_ref().and_then(|source| source.as_dyn_error().backtrace())
if let std::option::Option::Some(source) = #varsource {
source.as_dyn_error().provide(#demand);
}
}
} else {
quote_spanned! {source.span()=>
#varsource.as_dyn_error().backtrace()
#varsource.as_dyn_error().provide(#demand);
}
};
let combinator = if type_is_option(backtrace_field.ty) {
let self_provide = if type_is_option(backtrace_field.ty) {
quote! {
#source_backtrace.or(backtrace.as_ref())
if let std::option::Option::Some(backtrace) = backtrace {
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
}
} else {
quote! {
std::option::Option::Some(#source_backtrace.unwrap_or(backtrace))
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
};
quote! {
Expand All @@ -272,7 +285,8 @@ fn impl_enum(input: Enum) -> TokenStream {
..
} => {
use thiserror::__private::AsDynError;
#combinator
#source_provide
#self_provide
}
}
}
Expand All @@ -281,40 +295,50 @@ fn impl_enum(input: Enum) -> TokenStream {
{
let backtrace = &backtrace_field.member;
let varsource = quote!(source);
let source_backtrace = if type_is_option(source_field.ty) {
let source_provide = if type_is_option(source_field.ty) {
quote_spanned! {backtrace.span()=>
#varsource.as_ref().and_then(|source| source.as_dyn_error().backtrace())
if let std::option::Option::Some(source) = #varsource {
source.as_dyn_error().provide(#demand);
}
}
} else {
quote_spanned! {backtrace.span()=>
#varsource.as_dyn_error().backtrace()
#varsource.as_dyn_error().provide(#demand);
}
};
quote! {
#ty::#ident {#backtrace: #varsource, ..} => {
use thiserror::__private::AsDynError;
#source_backtrace
#source_provide
}
}
}
(Some(backtrace_field), _) => {
let backtrace = &backtrace_field.member;
let body = if type_is_option(backtrace_field.ty) {
quote!(backtrace.as_ref())
quote! {
if let std::option::Option::Some(backtrace) = backtrace {
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
}
} else {
quote!(std::option::Option::Some(backtrace))
quote! {
#demand.provide_ref::<std::backtrace::Backtrace>(backtrace);
}
};
quote! {
#ty::#ident {#backtrace: backtrace, ..} => #body,
#ty::#ident {#backtrace: backtrace, ..} => {
#body
}
}
}
(None, _) => quote! {
#ty::#ident {..} => std::option::Option::None,
#ty::#ident {..} => {}
},
}
});
Some(quote! {
fn backtrace(&self) -> std::option::Option<&std::backtrace::Backtrace> {
fn provide<'_demand>(&'_demand self, #demand: &mut std::any::Demand<'_demand>) {
#[allow(deprecated)]
match self {
#(#arms)*
Expand Down Expand Up @@ -420,7 +444,7 @@ fn impl_enum(input: Enum) -> TokenStream {
#[allow(unused_qualifications)]
impl #impl_generics #error_trait for #ty #ty_generics #error_where_clause {
#source_method
#backtrace_method
#provide_method
}
#display_impl
#(#from_impls)*
Expand Down
43 changes: 22 additions & 21 deletions tests/test_backtrace.rs
View file
Open in desktop
@@ -1,6 +1,7 @@
// FIXME: needs to be updated to provide_ref/request_ref API.
#![cfg(any())]
#![cfg_attr(thiserror_nightly_testing, feature(backtrace))]
#![cfg_attr(
thiserror_nightly_testing,
feature(error_generic_member_access, provide_any)
)]

use thiserror::Error;

Expand All @@ -18,8 +19,8 @@ pub struct InnerBacktrace {
#[cfg(thiserror_nightly_testing)]
pub mod structs {
use super::{Inner, InnerBacktrace};
use std::any;
use std::backtrace::Backtrace;
use std::error::Error;
use std::sync::Arc;
use thiserror::Error;

Expand Down Expand Up @@ -90,44 +91,44 @@ pub mod structs {
let error = PlainBacktrace {
backtrace: Backtrace::capture(),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ExplicitBacktrace {
backtrace: Backtrace::capture(),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = OptBacktrace {
backtrace: Some(Backtrace::capture()),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ArcBacktrace {
backtrace: Arc::new(Backtrace::capture()),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = BacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = CombinedBacktraceFrom::from(InnerBacktrace {
backtrace: Backtrace::capture(),
});
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = OptBacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ArcBacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());
}
}

#[cfg(thiserror_nightly_testing)]
pub mod enums {
use super::{Inner, InnerBacktrace};
use std::any;
use std::backtrace::Backtrace;
use std::error::Error;
use std::sync::Arc;
use thiserror::Error;

Expand Down Expand Up @@ -212,36 +213,36 @@ pub mod enums {
let error = PlainBacktrace::Test {
backtrace: Backtrace::capture(),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ExplicitBacktrace::Test {
backtrace: Backtrace::capture(),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = OptBacktrace::Test {
backtrace: Some(Backtrace::capture()),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ArcBacktrace::Test {
backtrace: Arc::new(Backtrace::capture()),
};
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = BacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = CombinedBacktraceFrom::from(InnerBacktrace {
backtrace: Backtrace::capture(),
});
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = OptBacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());

let error = ArcBacktraceFrom::from(Inner);
assert!(error.backtrace().is_some());
assert!(any::request_ref::<Backtrace>(&error).is_some());
}
}

Expand Down
7 changes: 4 additions & 3 deletions tests/test_option.rs
View file
Open in desktop
@@ -1,6 +1,7 @@
// FIXME: needs to be updated to provide_ref/request_ref API.
#![cfg(any())]
#![cfg_attr(thiserror_nightly_testing, feature(backtrace))]
#![cfg_attr(
thiserror_nightly_testing,
feature(error_generic_member_access, provide_any)
)]

#[cfg(thiserror_nightly_testing)]
pub mod structs {
Expand Down