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Consistently use quote! when emitting 'source'

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When a macro generates part of the derive input, the call-site hygiene
may be different than the hygiene of a field. Therefore, we need to
be sure to use the same hygiene information for any identifiers we
generate, instead of relying on the hygiene from a particular span
via `quote_spanned!`
This commit is contained in:
Aaron Hill 2021-02-18 11:45:27 -05:00
parent d0f521c208
commit 0fa679b1b8
No known key found for this signature in database
GPG key ID: B4087E510E98B164
2 changed files with 20 additions and 5 deletions
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12
impl/src/expand.rs
View file

@ -171,9 +171,10 @@ fn impl_enum(input: Enum) -> TokenStream {
} else {
None
};
let dyn_error = quote_spanned!(source.span()=> source #asref.as_dyn_error());
let source_literal = quote! { source };
let dyn_error = quote_spanned!(source.span()=> #source_literal #asref.as_dyn_error());
quote! {
#ty::#ident {#source: source, ..} => std::option::Option::Some(#dyn_error),
#ty::#ident {#source: #source_literal, ..} => std::option::Option::Some(#dyn_error),
}
} else {
quote! {
@ -203,13 +204,14 @@ fn impl_enum(input: Enum) -> TokenStream {
{
let backtrace = &backtrace_field.member;
let source = &source_field.member;
let source_literal = quote! { source };
let source_backtrace = if type_is_option(source_field.ty) {
quote_spanned! {source.span()=>
source.as_ref().and_then(|source| source.as_dyn_error().backtrace())
#source_literal.as_ref().and_then(|source| #source_literal.as_dyn_error().backtrace())
}
} else {
quote_spanned! {source.span()=>
source.as_dyn_error().backtrace()
#source_literal.as_dyn_error().backtrace()
}
};
let combinator = if type_is_option(backtrace_field.ty) {
@ -224,7 +226,7 @@ fn impl_enum(input: Enum) -> TokenStream {
quote! {
#ty::#ident {
#backtrace: backtrace,
#source: source,
#source: #source_literal,
..
} => {
use thiserror::private::AsDynError;

13
tests/test_source.rs
View file

@ -48,3 +48,16 @@ fn test_boxed_source() {
let error = BoxedSource { source };
error.source().unwrap().downcast_ref::<io::Error>().unwrap();
}
macro_rules! error_from_macro {
($($variants:tt)*) => {
#[derive(Error)]
#[derive(Debug)]
pub enum MacroSource {
$($variants)*
}
}
}
// Test that we generate impls with the proper hygiene
error_from_macro!(#[error("Something")] Variant(#[from] io::Error));