diff options
Diffstat (limited to 'vendor/thiserror-impl/src/expand.rs')
| -rw-r--r-- | vendor/thiserror-impl/src/expand.rs | 562 |
1 files changed, 562 insertions, 0 deletions
diff --git a/vendor/thiserror-impl/src/expand.rs b/vendor/thiserror-impl/src/expand.rs new file mode 100644 index 0000000..1b44513 --- /dev/null +++ b/vendor/thiserror-impl/src/expand.rs @@ -0,0 +1,562 @@ +use crate::ast::{Enum, Field, Input, Struct}; +use crate::attr::Trait; +use crate::generics::InferredBounds; +use crate::span::MemberSpan; +use proc_macro2::TokenStream; +use quote::{format_ident, quote, quote_spanned, ToTokens}; +use std::collections::BTreeSet as Set; +use syn::{DeriveInput, GenericArgument, Member, PathArguments, Result, Token, Type}; + +pub fn derive(input: &DeriveInput) -> TokenStream { + match try_expand(input) { + Ok(expanded) => expanded, + // If there are invalid attributes in the input, expand to an Error impl + // anyway to minimize spurious knock-on errors in other code that uses + // this type as an Error. + Err(error) => fallback(input, error), + } +} + +fn try_expand(input: &DeriveInput) -> Result<TokenStream> { + let input = Input::from_syn(input)?; + input.validate()?; + Ok(match input { + Input::Struct(input) => impl_struct(input), + Input::Enum(input) => impl_enum(input), + }) +} + +fn fallback(input: &DeriveInput, error: syn::Error) -> TokenStream { + let ty = &input.ident; + let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); + + let error = error.to_compile_error(); + + quote! { + #error + + #[allow(unused_qualifications)] + impl #impl_generics std::error::Error for #ty #ty_generics #where_clause + where + // Work around trivial bounds being unstable. + // https://github.com/rust-lang/rust/issues/48214 + for<'workaround> #ty #ty_generics: ::core::fmt::Debug, + {} + + #[allow(unused_qualifications)] + impl #impl_generics ::core::fmt::Display for #ty #ty_generics #where_clause { + fn fmt(&self, __formatter: &mut ::core::fmt::Formatter) -> ::core::fmt::Result { + ::core::unreachable!() + } + } + } +} + +fn impl_struct(input: Struct) -> TokenStream { + let ty = &input.ident; + let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); + let mut error_inferred_bounds = InferredBounds::new(); + + let source_body = if let Some(transparent_attr) = &input.attrs.transparent { + let only_field = &input.fields[0]; + if only_field.contains_generic { + error_inferred_bounds.insert(only_field.ty, quote!(std::error::Error)); + } + let member = &only_field.member; + Some(quote_spanned! {transparent_attr.span=> + std::error::Error::source(self.#member.as_dyn_error()) + }) + } else if let Some(source_field) = input.source_field() { + let source = &source_field.member; + if source_field.contains_generic { + let ty = unoptional_type(source_field.ty); + error_inferred_bounds.insert(ty, quote!(std::error::Error + 'static)); + } + let asref = if type_is_option(source_field.ty) { + Some(quote_spanned!(source.member_span()=> .as_ref()?)) + } else { + None + }; + let dyn_error = quote_spanned! {source_field.source_span()=> + self.#source #asref.as_dyn_error() + }; + Some(quote! { + ::core::option::Option::Some(#dyn_error) + }) + } else { + None + }; + let source_method = source_body.map(|body| { + quote! { + fn source(&self) -> ::core::option::Option<&(dyn std::error::Error + 'static)> { + use thiserror::__private::AsDynError as _; + #body + } + } + }); + + let provide_method = input.backtrace_field().map(|backtrace_field| { + let request = quote!(request); + let backtrace = &backtrace_field.member; + let body = if let Some(source_field) = input.source_field() { + let source = &source_field.member; + let source_provide = if type_is_option(source_field.ty) { + quote_spanned! {source.member_span()=> + if let ::core::option::Option::Some(source) = &self.#source { + source.thiserror_provide(#request); + } + } + } else { + quote_spanned! {source.member_span()=> + self.#source.thiserror_provide(#request); + } + }; + let self_provide = if source == backtrace { + None + } else if type_is_option(backtrace_field.ty) { + Some(quote! { + if let ::core::option::Option::Some(backtrace) = &self.#backtrace { + #request.provide_ref::<std::backtrace::Backtrace>(backtrace); + } + }) + } else { + Some(quote! { + #request.provide_ref::<std::backtrace::Backtrace>(&self.#backtrace); + }) + }; + quote! { + use thiserror::__private::ThiserrorProvide as _; + #source_provide + #self_provide + } + } else if type_is_option(backtrace_field.ty) { + quote! { + if let ::core::option::Option::Some(backtrace) = &self.#backtrace { + #request.provide_ref::<std::backtrace::Backtrace>(backtrace); + } + } + } else { + quote! { + #request.provide_ref::<std::backtrace::Backtrace>(&self.#backtrace); + } + }; + quote! { + fn provide<'_request>(&'_request self, #request: &mut std::error::Request<'_request>) { + #body + } + } + }); + + let mut display_implied_bounds = Set::new(); + let display_body = if input.attrs.transparent.is_some() { + let only_field = &input.fields[0].member; + display_implied_bounds.insert((0, Trait::Display)); + Some(quote! { + ::core::fmt::Display::fmt(&self.#only_field, __formatter) + }) + } else if let Some(display) = &input.attrs.display { + display_implied_bounds = display.implied_bounds.clone(); + let use_as_display = use_as_display(display.has_bonus_display); + let pat = fields_pat(&input.fields); + Some(quote! { + #use_as_display + #[allow(unused_variables, deprecated)] + let Self #pat = self; + #display + }) + } else { + None + }; + let display_impl = display_body.map(|body| { + let mut display_inferred_bounds = InferredBounds::new(); + for (field, bound) in display_implied_bounds { + let field = &input.fields[field]; + if field.contains_generic { + display_inferred_bounds.insert(field.ty, bound); + } + } + let display_where_clause = display_inferred_bounds.augment_where_clause(input.generics); + quote! { + #[allow(unused_qualifications)] + impl #impl_generics ::core::fmt::Display for #ty #ty_generics #display_where_clause { + #[allow(clippy::used_underscore_binding)] + fn fmt(&self, __formatter: &mut ::core::fmt::Formatter) -> ::core::fmt::Result { + #body + } + } + } + }); + + 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); + quote! { + #[allow(unused_qualifications)] + impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause { + #[allow(deprecated)] + fn from(source: #from) -> Self { + #ty #body + } + } + } + }); + + if input.generics.type_params().next().is_some() { + let self_token = <Token![Self]>::default(); + error_inferred_bounds.insert(self_token, Trait::Debug); + error_inferred_bounds.insert(self_token, Trait::Display); + } + let error_where_clause = error_inferred_bounds.augment_where_clause(input.generics); + + quote! { + #[allow(unused_qualifications)] + impl #impl_generics std::error::Error for #ty #ty_generics #error_where_clause { + #source_method + #provide_method + } + #display_impl + #from_impl + } +} + +fn impl_enum(input: Enum) -> TokenStream { + let ty = &input.ident; + let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); + let mut error_inferred_bounds = InferredBounds::new(); + + let source_method = if input.has_source() { + let arms = input.variants.iter().map(|variant| { + let ident = &variant.ident; + if let Some(transparent_attr) = &variant.attrs.transparent { + let only_field = &variant.fields[0]; + if only_field.contains_generic { + error_inferred_bounds.insert(only_field.ty, quote!(std::error::Error)); + } + let member = &only_field.member; + let source = quote_spanned! {transparent_attr.span=> + std::error::Error::source(transparent.as_dyn_error()) + }; + quote! { + #ty::#ident {#member: transparent} => #source, + } + } else if let Some(source_field) = variant.source_field() { + let source = &source_field.member; + if source_field.contains_generic { + let ty = unoptional_type(source_field.ty); + error_inferred_bounds.insert(ty, quote!(std::error::Error + 'static)); + } + let asref = if type_is_option(source_field.ty) { + Some(quote_spanned!(source.member_span()=> .as_ref()?)) + } else { + None + }; + let varsource = quote!(source); + let dyn_error = quote_spanned! {source_field.source_span()=> + #varsource #asref.as_dyn_error() + }; + quote! { + #ty::#ident {#source: #varsource, ..} => ::core::option::Option::Some(#dyn_error), + } + } else { + quote! { + #ty::#ident {..} => ::core::option::Option::None, + } + } + }); + Some(quote! { + fn source(&self) -> ::core::option::Option<&(dyn std::error::Error + 'static)> { + use thiserror::__private::AsDynError as _; + #[allow(deprecated)] + match self { + #(#arms)* + } + } + }) + } else { + None + }; + + let provide_method = if input.has_backtrace() { + 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); + } + } + } else { + quote_spanned! {source.member_span()=> + #varsource.thiserror_provide(#request); + } + }; + let self_provide = 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); + } + }; + quote! { + #ty::#ident { + #backtrace: backtrace, + #source: #varsource, + .. + } => { + use thiserror::__private::ThiserrorProvide as _; + #source_provide + #self_provide + } + } + } + (Some(backtrace_field), Some(source_field)) + if backtrace_field.member == source_field.member => + { + 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); + } + } + } else { + quote_spanned! {backtrace.member_span()=> + #varsource.thiserror_provide(#request); + } + }; + quote! { + #ty::#ident {#backtrace: #varsource, ..} => { + use thiserror::__private::ThiserrorProvide as _; + #source_provide + } + } + } + (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); + } + }; + quote! { + #ty::#ident {#backtrace: backtrace, ..} => { + #body + } + } + } + (None, _) => quote! { + #ty::#ident {..} => {} + }, + } + }); + Some(quote! { + fn provide<'_request>(&'_request self, #request: &mut std::error::Request<'_request>) { + #[allow(deprecated)] + match self { + #(#arms)* + } + } + }) + } else { + None + }; + + let display_impl = if input.has_display() { + let mut display_inferred_bounds = InferredBounds::new(); + let has_bonus_display = input.variants.iter().any(|v| { + v.attrs + .display + .as_ref() + .map_or(false, |display| display.has_bonus_display) + }); + let use_as_display = use_as_display(has_bonus_display); + let void_deref = if input.variants.is_empty() { + Some(quote!(*)) + } else { + None + }; + let arms = input.variants.iter().map(|variant| { + let mut display_implied_bounds = Set::new(); + let display = match &variant.attrs.display { + Some(display) => { + display_implied_bounds = display.implied_bounds.clone(); + display.to_token_stream() + } + None => { + let only_field = match &variant.fields[0].member { + Member::Named(ident) => ident.clone(), + Member::Unnamed(index) => format_ident!("_{}", index), + }; + display_implied_bounds.insert((0, Trait::Display)); + quote!(::core::fmt::Display::fmt(#only_field, __formatter)) + } + }; + for (field, bound) in display_implied_bounds { + let field = &variant.fields[field]; + if field.contains_generic { + display_inferred_bounds.insert(field.ty, bound); + } + } + let ident = &variant.ident; + let pat = fields_pat(&variant.fields); + quote! { + #ty::#ident #pat => #display + } + }); + let arms = arms.collect::<Vec<_>>(); + let display_where_clause = display_inferred_bounds.augment_where_clause(input.generics); + Some(quote! { + #[allow(unused_qualifications)] + impl #impl_generics ::core::fmt::Display for #ty #ty_generics #display_where_clause { + fn fmt(&self, __formatter: &mut ::core::fmt::Formatter) -> ::core::fmt::Result { + #use_as_display + #[allow(unused_variables, deprecated, clippy::used_underscore_binding)] + match #void_deref self { + #(#arms,)* + } + } + } + }) + } else { + None + }; + + let from_impls = input.variants.iter().filter_map(|variant| { + let from_field = variant.from_field()?; + let backtrace_field = variant.distinct_backtrace_field(); + let variant = &variant.ident; + let from = unoptional_type(from_field.ty); + let body = from_initializer(from_field, backtrace_field); + Some(quote! { + #[allow(unused_qualifications)] + impl #impl_generics ::core::convert::From<#from> for #ty #ty_generics #where_clause { + #[allow(deprecated)] + fn from(source: #from) -> Self { + #ty::#variant #body + } + } + }) + }); + + if input.generics.type_params().next().is_some() { + let self_token = <Token![Self]>::default(); + error_inferred_bounds.insert(self_token, Trait::Debug); + error_inferred_bounds.insert(self_token, Trait::Display); + } + let error_where_clause = error_inferred_bounds.augment_where_clause(input.generics); + + quote! { + #[allow(unused_qualifications)] + impl #impl_generics std::error::Error for #ty #ty_generics #error_where_clause { + #source_method + #provide_method + } + #display_impl + #(#from_impls)* + } +} + +fn fields_pat(fields: &[Field]) -> TokenStream { + let mut members = fields.iter().map(|field| &field.member).peekable(); + match members.peek() { + Some(Member::Named(_)) => quote!({ #(#members),* }), + Some(Member::Unnamed(_)) => { + let vars = members.map(|member| match member { + Member::Unnamed(member) => format_ident!("_{}", member), + Member::Named(_) => unreachable!(), + }); + quote!((#(#vars),*)) + } + None => quote!({}), + } +} + +fn use_as_display(needs_as_display: bool) -> Option<TokenStream> { + if needs_as_display { + Some(quote! { + use thiserror::__private::AsDisplay as _; + }) + } else { + None + } +} + +fn from_initializer(from_field: &Field, backtrace_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)) + } else { + quote!(source) + }; + let backtrace = backtrace_field.map(|backtrace_field| { + let backtrace_member = &backtrace_field.member; + if type_is_option(backtrace_field.ty) { + quote! { + #backtrace_member: ::core::option::Option::Some(std::backtrace::Backtrace::capture()), + } + } else { + quote! { + #backtrace_member: ::core::convert::From::from(std::backtrace::Backtrace::capture()), + } + } + }); + quote!({ + #from_member: #some_source, + #backtrace + }) +} + +fn type_is_option(ty: &Type) -> bool { + type_parameter_of_option(ty).is_some() +} + +fn unoptional_type(ty: &Type) -> TokenStream { + let unoptional = type_parameter_of_option(ty).unwrap_or(ty); + quote!(#unoptional) +} + +fn type_parameter_of_option(ty: &Type) -> Option<&Type> { + let path = match ty { + Type::Path(ty) => &ty.path, + _ => return None, + }; + + let last = path.segments.last().unwrap(); + if last.ident != "Option" { + return None; + } + + let bracketed = match &last.arguments { + PathArguments::AngleBracketed(bracketed) => bracketed, + _ => return None, + }; + + if bracketed.args.len() != 1 { + return None; + } + + match &bracketed.args[0] { + GenericArgument::Type(arg) => Some(arg), + _ => None, + } +} |