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-rw-r--r--third_party/rust/thiserror-impl/src/ast.rs161
-rw-r--r--third_party/rust/thiserror-impl/src/attr.rs210
-rw-r--r--third_party/rust/thiserror-impl/src/expand.rs562
-rw-r--r--third_party/rust/thiserror-impl/src/fmt.rs170
-rw-r--r--third_party/rust/thiserror-impl/src/generics.rs83
-rw-r--r--third_party/rust/thiserror-impl/src/lib.rs36
-rw-r--r--third_party/rust/thiserror-impl/src/prop.rs147
-rw-r--r--third_party/rust/thiserror-impl/src/span.rs15
-rw-r--r--third_party/rust/thiserror-impl/src/valid.rs237
9 files changed, 1621 insertions, 0 deletions
diff --git a/third_party/rust/thiserror-impl/src/ast.rs b/third_party/rust/thiserror-impl/src/ast.rs
new file mode 100644
index 0000000000..9e06928980
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/ast.rs
@@ -0,0 +1,161 @@
+use crate::attr::{self, Attrs};
+use crate::generics::ParamsInScope;
+use proc_macro2::Span;
+use syn::{
+ Data, DataEnum, DataStruct, DeriveInput, Error, Fields, Generics, Ident, Index, Member, Result,
+ Type,
+};
+
+pub enum Input<'a> {
+ Struct(Struct<'a>),
+ Enum(Enum<'a>),
+}
+
+pub struct Struct<'a> {
+ pub attrs: Attrs<'a>,
+ pub ident: Ident,
+ pub generics: &'a Generics,
+ pub fields: Vec<Field<'a>>,
+}
+
+pub struct Enum<'a> {
+ pub attrs: Attrs<'a>,
+ pub ident: Ident,
+ pub generics: &'a Generics,
+ pub variants: Vec<Variant<'a>>,
+}
+
+pub struct Variant<'a> {
+ pub original: &'a syn::Variant,
+ pub attrs: Attrs<'a>,
+ pub ident: Ident,
+ pub fields: Vec<Field<'a>>,
+}
+
+pub struct Field<'a> {
+ pub original: &'a syn::Field,
+ pub attrs: Attrs<'a>,
+ pub member: Member,
+ pub ty: &'a Type,
+ pub contains_generic: bool,
+}
+
+impl<'a> Input<'a> {
+ pub fn from_syn(node: &'a DeriveInput) -> Result<Self> {
+ match &node.data {
+ Data::Struct(data) => Struct::from_syn(node, data).map(Input::Struct),
+ Data::Enum(data) => Enum::from_syn(node, data).map(Input::Enum),
+ Data::Union(_) => Err(Error::new_spanned(
+ node,
+ "union as errors are not supported",
+ )),
+ }
+ }
+}
+
+impl<'a> Struct<'a> {
+ fn from_syn(node: &'a DeriveInput, data: &'a DataStruct) -> Result<Self> {
+ let mut attrs = attr::get(&node.attrs)?;
+ let scope = ParamsInScope::new(&node.generics);
+ let span = attrs.span().unwrap_or_else(Span::call_site);
+ let fields = Field::multiple_from_syn(&data.fields, &scope, span)?;
+ if let Some(display) = &mut attrs.display {
+ display.expand_shorthand(&fields);
+ }
+ Ok(Struct {
+ attrs,
+ ident: node.ident.clone(),
+ generics: &node.generics,
+ fields,
+ })
+ }
+}
+
+impl<'a> Enum<'a> {
+ fn from_syn(node: &'a DeriveInput, data: &'a DataEnum) -> Result<Self> {
+ let attrs = attr::get(&node.attrs)?;
+ let scope = ParamsInScope::new(&node.generics);
+ let span = attrs.span().unwrap_or_else(Span::call_site);
+ let variants = data
+ .variants
+ .iter()
+ .map(|node| {
+ let mut variant = Variant::from_syn(node, &scope, span)?;
+ if let display @ None = &mut variant.attrs.display {
+ *display = attrs.display.clone();
+ }
+ if let Some(display) = &mut variant.attrs.display {
+ display.expand_shorthand(&variant.fields);
+ } else if variant.attrs.transparent.is_none() {
+ variant.attrs.transparent = attrs.transparent;
+ }
+ Ok(variant)
+ })
+ .collect::<Result<_>>()?;
+ Ok(Enum {
+ attrs,
+ ident: node.ident.clone(),
+ generics: &node.generics,
+ variants,
+ })
+ }
+}
+
+impl<'a> Variant<'a> {
+ fn from_syn(node: &'a syn::Variant, scope: &ParamsInScope<'a>, span: Span) -> Result<Self> {
+ let attrs = attr::get(&node.attrs)?;
+ let span = attrs.span().unwrap_or(span);
+ Ok(Variant {
+ original: node,
+ attrs,
+ ident: node.ident.clone(),
+ fields: Field::multiple_from_syn(&node.fields, scope, span)?,
+ })
+ }
+}
+
+impl<'a> Field<'a> {
+ fn multiple_from_syn(
+ fields: &'a Fields,
+ scope: &ParamsInScope<'a>,
+ span: Span,
+ ) -> Result<Vec<Self>> {
+ fields
+ .iter()
+ .enumerate()
+ .map(|(i, field)| Field::from_syn(i, field, scope, span))
+ .collect()
+ }
+
+ fn from_syn(
+ i: usize,
+ node: &'a syn::Field,
+ scope: &ParamsInScope<'a>,
+ span: Span,
+ ) -> Result<Self> {
+ Ok(Field {
+ original: node,
+ attrs: attr::get(&node.attrs)?,
+ member: node.ident.clone().map(Member::Named).unwrap_or_else(|| {
+ Member::Unnamed(Index {
+ index: i as u32,
+ span,
+ })
+ }),
+ ty: &node.ty,
+ contains_generic: scope.intersects(&node.ty),
+ })
+ }
+}
+
+impl Attrs<'_> {
+ pub fn span(&self) -> Option<Span> {
+ if let Some(display) = &self.display {
+ Some(display.fmt.span())
+ } else if let Some(transparent) = &self.transparent {
+ Some(transparent.span)
+ } else {
+ None
+ }
+ }
+}
diff --git a/third_party/rust/thiserror-impl/src/attr.rs b/third_party/rust/thiserror-impl/src/attr.rs
new file mode 100644
index 0000000000..4beb8c9628
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/attr.rs
@@ -0,0 +1,210 @@
+use proc_macro2::{Delimiter, Group, Span, TokenStream, TokenTree};
+use quote::{format_ident, quote, ToTokens};
+use std::collections::BTreeSet as Set;
+use syn::parse::ParseStream;
+use syn::{
+ braced, bracketed, parenthesized, token, Attribute, Error, Ident, Index, LitInt, LitStr, Meta,
+ Result, Token,
+};
+
+pub struct Attrs<'a> {
+ pub display: Option<Display<'a>>,
+ pub source: Option<&'a Attribute>,
+ pub backtrace: Option<&'a Attribute>,
+ pub from: Option<&'a Attribute>,
+ pub transparent: Option<Transparent<'a>>,
+}
+
+#[derive(Clone)]
+pub struct Display<'a> {
+ pub original: &'a Attribute,
+ pub fmt: LitStr,
+ pub args: TokenStream,
+ pub has_bonus_display: bool,
+ pub implied_bounds: Set<(usize, Trait)>,
+}
+
+#[derive(Copy, Clone)]
+pub struct Transparent<'a> {
+ pub original: &'a Attribute,
+ pub span: Span,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Debug)]
+pub enum Trait {
+ Debug,
+ Display,
+ Octal,
+ LowerHex,
+ UpperHex,
+ Pointer,
+ Binary,
+ LowerExp,
+ UpperExp,
+}
+
+pub fn get(input: &[Attribute]) -> Result<Attrs> {
+ let mut attrs = Attrs {
+ display: None,
+ source: None,
+ backtrace: None,
+ from: None,
+ transparent: None,
+ };
+
+ for attr in input {
+ if attr.path().is_ident("error") {
+ parse_error_attribute(&mut attrs, attr)?;
+ } else if attr.path().is_ident("source") {
+ attr.meta.require_path_only()?;
+ if attrs.source.is_some() {
+ return Err(Error::new_spanned(attr, "duplicate #[source] attribute"));
+ }
+ attrs.source = Some(attr);
+ } else if attr.path().is_ident("backtrace") {
+ attr.meta.require_path_only()?;
+ if attrs.backtrace.is_some() {
+ return Err(Error::new_spanned(attr, "duplicate #[backtrace] attribute"));
+ }
+ attrs.backtrace = Some(attr);
+ } else if attr.path().is_ident("from") {
+ match attr.meta {
+ Meta::Path(_) => {}
+ Meta::List(_) | Meta::NameValue(_) => {
+ // Assume this is meant for derive_more crate or something.
+ continue;
+ }
+ }
+ if attrs.from.is_some() {
+ return Err(Error::new_spanned(attr, "duplicate #[from] attribute"));
+ }
+ attrs.from = Some(attr);
+ }
+ }
+
+ Ok(attrs)
+}
+
+fn parse_error_attribute<'a>(attrs: &mut Attrs<'a>, attr: &'a Attribute) -> Result<()> {
+ syn::custom_keyword!(transparent);
+
+ attr.parse_args_with(|input: ParseStream| {
+ if let Some(kw) = input.parse::<Option<transparent>>()? {
+ if attrs.transparent.is_some() {
+ return Err(Error::new_spanned(
+ attr,
+ "duplicate #[error(transparent)] attribute",
+ ));
+ }
+ attrs.transparent = Some(Transparent {
+ original: attr,
+ span: kw.span,
+ });
+ return Ok(());
+ }
+
+ let display = Display {
+ original: attr,
+ fmt: input.parse()?,
+ args: parse_token_expr(input, false)?,
+ has_bonus_display: false,
+ implied_bounds: Set::new(),
+ };
+ if attrs.display.is_some() {
+ return Err(Error::new_spanned(
+ attr,
+ "only one #[error(...)] attribute is allowed",
+ ));
+ }
+ attrs.display = Some(display);
+ Ok(())
+ })
+}
+
+fn parse_token_expr(input: ParseStream, mut begin_expr: bool) -> Result<TokenStream> {
+ let mut tokens = Vec::new();
+ while !input.is_empty() {
+ if begin_expr && input.peek(Token![.]) {
+ if input.peek2(Ident) {
+ input.parse::<Token![.]>()?;
+ begin_expr = false;
+ continue;
+ }
+ if input.peek2(LitInt) {
+ input.parse::<Token![.]>()?;
+ let int: Index = input.parse()?;
+ let ident = format_ident!("_{}", int.index, span = int.span);
+ tokens.push(TokenTree::Ident(ident));
+ begin_expr = false;
+ continue;
+ }
+ }
+
+ begin_expr = input.peek(Token![break])
+ || input.peek(Token![continue])
+ || input.peek(Token![if])
+ || input.peek(Token![in])
+ || input.peek(Token![match])
+ || input.peek(Token![mut])
+ || input.peek(Token![return])
+ || input.peek(Token![while])
+ || input.peek(Token![+])
+ || input.peek(Token![&])
+ || input.peek(Token![!])
+ || input.peek(Token![^])
+ || input.peek(Token![,])
+ || input.peek(Token![/])
+ || input.peek(Token![=])
+ || input.peek(Token![>])
+ || input.peek(Token![<])
+ || input.peek(Token![|])
+ || input.peek(Token![%])
+ || input.peek(Token![;])
+ || input.peek(Token![*])
+ || input.peek(Token![-]);
+
+ let token: TokenTree = if input.peek(token::Paren) {
+ let content;
+ let delimiter = parenthesized!(content in input);
+ let nested = parse_token_expr(&content, true)?;
+ let mut group = Group::new(Delimiter::Parenthesis, nested);
+ group.set_span(delimiter.span.join());
+ TokenTree::Group(group)
+ } else if input.peek(token::Brace) {
+ let content;
+ let delimiter = braced!(content in input);
+ let nested = parse_token_expr(&content, true)?;
+ let mut group = Group::new(Delimiter::Brace, nested);
+ group.set_span(delimiter.span.join());
+ TokenTree::Group(group)
+ } else if input.peek(token::Bracket) {
+ let content;
+ let delimiter = bracketed!(content in input);
+ let nested = parse_token_expr(&content, true)?;
+ let mut group = Group::new(Delimiter::Bracket, nested);
+ group.set_span(delimiter.span.join());
+ TokenTree::Group(group)
+ } else {
+ input.parse()?
+ };
+ tokens.push(token);
+ }
+ Ok(TokenStream::from_iter(tokens))
+}
+
+impl ToTokens for Display<'_> {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ let fmt = &self.fmt;
+ let args = &self.args;
+ tokens.extend(quote! {
+ ::core::write!(__formatter, #fmt #args)
+ });
+ }
+}
+
+impl ToTokens for Trait {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ let trait_name = format_ident!("{}", format!("{:?}", self));
+ tokens.extend(quote!(::core::fmt::#trait_name));
+ }
+}
diff --git a/third_party/rust/thiserror-impl/src/expand.rs b/third_party/rust/thiserror-impl/src/expand.rs
new file mode 100644
index 0000000000..1b44513a23
--- /dev/null
+++ b/third_party/rust/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,
+ }
+}
diff --git a/third_party/rust/thiserror-impl/src/fmt.rs b/third_party/rust/thiserror-impl/src/fmt.rs
new file mode 100644
index 0000000000..807dfb9677
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/fmt.rs
@@ -0,0 +1,170 @@
+use crate::ast::Field;
+use crate::attr::{Display, Trait};
+use proc_macro2::TokenTree;
+use quote::{format_ident, quote_spanned};
+use std::collections::{BTreeSet as Set, HashMap as Map};
+use syn::ext::IdentExt;
+use syn::parse::{ParseStream, Parser};
+use syn::{Ident, Index, LitStr, Member, Result, Token};
+
+impl Display<'_> {
+ // Transform `"error {var}"` to `"error {}", var`.
+ pub fn expand_shorthand(&mut self, fields: &[Field]) {
+ let raw_args = self.args.clone();
+ let mut named_args = explicit_named_args.parse2(raw_args).unwrap();
+ let mut member_index = Map::new();
+ for (i, field) in fields.iter().enumerate() {
+ member_index.insert(&field.member, i);
+ }
+
+ let span = self.fmt.span();
+ let fmt = self.fmt.value();
+ let mut read = fmt.as_str();
+ let mut out = String::new();
+ let mut args = self.args.clone();
+ let mut has_bonus_display = false;
+ let mut implied_bounds = Set::new();
+
+ let mut has_trailing_comma = false;
+ if let Some(TokenTree::Punct(punct)) = args.clone().into_iter().last() {
+ if punct.as_char() == ',' {
+ has_trailing_comma = true;
+ }
+ }
+
+ while let Some(brace) = read.find('{') {
+ out += &read[..brace + 1];
+ read = &read[brace + 1..];
+ if read.starts_with('{') {
+ out.push('{');
+ read = &read[1..];
+ continue;
+ }
+ let next = match read.chars().next() {
+ Some(next) => next,
+ None => return,
+ };
+ let member = match next {
+ '0'..='9' => {
+ let int = take_int(&mut read);
+ let member = match int.parse::<u32>() {
+ Ok(index) => Member::Unnamed(Index { index, span }),
+ Err(_) => return,
+ };
+ if !member_index.contains_key(&member) {
+ out += &int;
+ continue;
+ }
+ member
+ }
+ 'a'..='z' | 'A'..='Z' | '_' => {
+ let mut ident = take_ident(&mut read);
+ ident.set_span(span);
+ Member::Named(ident)
+ }
+ _ => continue,
+ };
+ if let Some(&field) = member_index.get(&member) {
+ let end_spec = match read.find('}') {
+ Some(end_spec) => end_spec,
+ None => return,
+ };
+ let bound = match read[..end_spec].chars().next_back() {
+ Some('?') => Trait::Debug,
+ Some('o') => Trait::Octal,
+ Some('x') => Trait::LowerHex,
+ Some('X') => Trait::UpperHex,
+ Some('p') => Trait::Pointer,
+ Some('b') => Trait::Binary,
+ Some('e') => Trait::LowerExp,
+ Some('E') => Trait::UpperExp,
+ Some(_) | None => Trait::Display,
+ };
+ implied_bounds.insert((field, bound));
+ }
+ let local = match &member {
+ Member::Unnamed(index) => format_ident!("_{}", index),
+ Member::Named(ident) => ident.clone(),
+ };
+ let mut formatvar = local.clone();
+ if formatvar.to_string().starts_with("r#") {
+ formatvar = format_ident!("r_{}", formatvar);
+ }
+ if formatvar.to_string().starts_with('_') {
+ // Work around leading underscore being rejected by 1.40 and
+ // older compilers. https://github.com/rust-lang/rust/pull/66847
+ formatvar = format_ident!("field_{}", formatvar);
+ }
+ out += &formatvar.to_string();
+ if !named_args.insert(formatvar.clone()) {
+ // Already specified in the format argument list.
+ continue;
+ }
+ if !has_trailing_comma {
+ args.extend(quote_spanned!(span=> ,));
+ }
+ args.extend(quote_spanned!(span=> #formatvar = #local));
+ if read.starts_with('}') && member_index.contains_key(&member) {
+ has_bonus_display = true;
+ args.extend(quote_spanned!(span=> .as_display()));
+ }
+ has_trailing_comma = false;
+ }
+
+ out += read;
+ self.fmt = LitStr::new(&out, self.fmt.span());
+ self.args = args;
+ self.has_bonus_display = has_bonus_display;
+ self.implied_bounds = implied_bounds;
+ }
+}
+
+fn explicit_named_args(input: ParseStream) -> Result<Set<Ident>> {
+ let mut named_args = Set::new();
+
+ while !input.is_empty() {
+ if input.peek(Token![,]) && input.peek2(Ident::peek_any) && input.peek3(Token![=]) {
+ input.parse::<Token![,]>()?;
+ let ident = input.call(Ident::parse_any)?;
+ input.parse::<Token![=]>()?;
+ named_args.insert(ident);
+ } else {
+ input.parse::<TokenTree>()?;
+ }
+ }
+
+ Ok(named_args)
+}
+
+fn take_int(read: &mut &str) -> String {
+ let mut int = String::new();
+ for (i, ch) in read.char_indices() {
+ match ch {
+ '0'..='9' => int.push(ch),
+ _ => {
+ *read = &read[i..];
+ break;
+ }
+ }
+ }
+ int
+}
+
+fn take_ident(read: &mut &str) -> Ident {
+ let mut ident = String::new();
+ let raw = read.starts_with("r#");
+ if raw {
+ ident.push_str("r#");
+ *read = &read[2..];
+ }
+ for (i, ch) in read.char_indices() {
+ match ch {
+ 'a'..='z' | 'A'..='Z' | '0'..='9' | '_' => ident.push(ch),
+ _ => {
+ *read = &read[i..];
+ break;
+ }
+ }
+ }
+ Ident::parse_any.parse_str(&ident).unwrap()
+}
diff --git a/third_party/rust/thiserror-impl/src/generics.rs b/third_party/rust/thiserror-impl/src/generics.rs
new file mode 100644
index 0000000000..95592a7370
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/generics.rs
@@ -0,0 +1,83 @@
+use proc_macro2::TokenStream;
+use quote::ToTokens;
+use std::collections::btree_map::Entry;
+use std::collections::{BTreeMap as Map, BTreeSet as Set};
+use syn::punctuated::Punctuated;
+use syn::{parse_quote, GenericArgument, Generics, Ident, PathArguments, Token, Type, WhereClause};
+
+pub struct ParamsInScope<'a> {
+ names: Set<&'a Ident>,
+}
+
+impl<'a> ParamsInScope<'a> {
+ pub fn new(generics: &'a Generics) -> Self {
+ ParamsInScope {
+ names: generics.type_params().map(|param| &param.ident).collect(),
+ }
+ }
+
+ pub fn intersects(&self, ty: &Type) -> bool {
+ let mut found = false;
+ crawl(self, ty, &mut found);
+ found
+ }
+}
+
+fn crawl(in_scope: &ParamsInScope, ty: &Type, found: &mut bool) {
+ if let Type::Path(ty) = ty {
+ if ty.qself.is_none() {
+ if let Some(ident) = ty.path.get_ident() {
+ if in_scope.names.contains(ident) {
+ *found = true;
+ }
+ }
+ }
+ for segment in &ty.path.segments {
+ if let PathArguments::AngleBracketed(arguments) = &segment.arguments {
+ for arg in &arguments.args {
+ if let GenericArgument::Type(ty) = arg {
+ crawl(in_scope, ty, found);
+ }
+ }
+ }
+ }
+ }
+}
+
+pub struct InferredBounds {
+ bounds: Map<String, (Set<String>, Punctuated<TokenStream, Token![+]>)>,
+ order: Vec<TokenStream>,
+}
+
+impl InferredBounds {
+ pub fn new() -> Self {
+ InferredBounds {
+ bounds: Map::new(),
+ order: Vec::new(),
+ }
+ }
+
+ #[allow(clippy::type_repetition_in_bounds, clippy::trait_duplication_in_bounds)] // clippy bug: https://github.com/rust-lang/rust-clippy/issues/8771
+ pub fn insert(&mut self, ty: impl ToTokens, bound: impl ToTokens) {
+ let ty = ty.to_token_stream();
+ let bound = bound.to_token_stream();
+ let entry = self.bounds.entry(ty.to_string());
+ if let Entry::Vacant(_) = entry {
+ self.order.push(ty);
+ }
+ let (set, tokens) = entry.or_default();
+ if set.insert(bound.to_string()) {
+ tokens.push(bound);
+ }
+ }
+
+ pub fn augment_where_clause(&self, generics: &Generics) -> WhereClause {
+ let mut generics = generics.clone();
+ let where_clause = generics.make_where_clause();
+ for ty in &self.order {
+ let (_set, bounds) = &self.bounds[&ty.to_string()];
+ where_clause.predicates.push(parse_quote!(#ty: #bounds));
+ }
+ generics.where_clause.unwrap()
+ }
+}
diff --git a/third_party/rust/thiserror-impl/src/lib.rs b/third_party/rust/thiserror-impl/src/lib.rs
new file mode 100644
index 0000000000..58f4bb5b5d
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/lib.rs
@@ -0,0 +1,36 @@
+#![allow(
+ clippy::blocks_in_conditions,
+ clippy::cast_lossless,
+ clippy::cast_possible_truncation,
+ clippy::manual_find,
+ clippy::manual_let_else,
+ clippy::manual_map,
+ clippy::map_unwrap_or,
+ clippy::module_name_repetitions,
+ clippy::needless_pass_by_value,
+ clippy::range_plus_one,
+ clippy::single_match_else,
+ clippy::struct_field_names,
+ clippy::too_many_lines,
+ clippy::wrong_self_convention
+)]
+
+extern crate proc_macro;
+
+mod ast;
+mod attr;
+mod expand;
+mod fmt;
+mod generics;
+mod prop;
+mod span;
+mod valid;
+
+use proc_macro::TokenStream;
+use syn::{parse_macro_input, DeriveInput};
+
+#[proc_macro_derive(Error, attributes(backtrace, error, from, source))]
+pub fn derive_error(input: TokenStream) -> TokenStream {
+ let input = parse_macro_input!(input as DeriveInput);
+ expand::derive(&input).into()
+}
diff --git a/third_party/rust/thiserror-impl/src/prop.rs b/third_party/rust/thiserror-impl/src/prop.rs
new file mode 100644
index 0000000000..2867cd312a
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/prop.rs
@@ -0,0 +1,147 @@
+use crate::ast::{Enum, Field, Struct, Variant};
+use crate::span::MemberSpan;
+use proc_macro2::Span;
+use syn::{Member, Type};
+
+impl Struct<'_> {
+ pub(crate) fn from_field(&self) -> Option<&Field> {
+ from_field(&self.fields)
+ }
+
+ pub(crate) fn source_field(&self) -> Option<&Field> {
+ source_field(&self.fields)
+ }
+
+ pub(crate) fn backtrace_field(&self) -> Option<&Field> {
+ backtrace_field(&self.fields)
+ }
+
+ pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
+ let backtrace_field = self.backtrace_field()?;
+ distinct_backtrace_field(backtrace_field, self.from_field())
+ }
+}
+
+impl Enum<'_> {
+ pub(crate) fn has_source(&self) -> bool {
+ self.variants
+ .iter()
+ .any(|variant| variant.source_field().is_some() || variant.attrs.transparent.is_some())
+ }
+
+ pub(crate) fn has_backtrace(&self) -> bool {
+ self.variants
+ .iter()
+ .any(|variant| variant.backtrace_field().is_some())
+ }
+
+ pub(crate) fn has_display(&self) -> bool {
+ self.attrs.display.is_some()
+ || self.attrs.transparent.is_some()
+ || self
+ .variants
+ .iter()
+ .any(|variant| variant.attrs.display.is_some())
+ || self
+ .variants
+ .iter()
+ .all(|variant| variant.attrs.transparent.is_some())
+ }
+}
+
+impl Variant<'_> {
+ pub(crate) fn from_field(&self) -> Option<&Field> {
+ from_field(&self.fields)
+ }
+
+ pub(crate) fn source_field(&self) -> Option<&Field> {
+ source_field(&self.fields)
+ }
+
+ pub(crate) fn backtrace_field(&self) -> Option<&Field> {
+ backtrace_field(&self.fields)
+ }
+
+ pub(crate) fn distinct_backtrace_field(&self) -> Option<&Field> {
+ let backtrace_field = self.backtrace_field()?;
+ distinct_backtrace_field(backtrace_field, self.from_field())
+ }
+}
+
+impl Field<'_> {
+ pub(crate) fn is_backtrace(&self) -> bool {
+ type_is_backtrace(self.ty)
+ }
+
+ pub(crate) fn source_span(&self) -> Span {
+ if let Some(source_attr) = &self.attrs.source {
+ source_attr.path().get_ident().unwrap().span()
+ } else if let Some(from_attr) = &self.attrs.from {
+ from_attr.path().get_ident().unwrap().span()
+ } else {
+ self.member.member_span()
+ }
+ }
+}
+
+fn from_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
+ for field in fields {
+ if field.attrs.from.is_some() {
+ return Some(field);
+ }
+ }
+ None
+}
+
+fn source_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
+ for field in fields {
+ if field.attrs.from.is_some() || field.attrs.source.is_some() {
+ return Some(field);
+ }
+ }
+ for field in fields {
+ match &field.member {
+ Member::Named(ident) if ident == "source" => return Some(field),
+ _ => {}
+ }
+ }
+ None
+}
+
+fn backtrace_field<'a, 'b>(fields: &'a [Field<'b>]) -> Option<&'a Field<'b>> {
+ for field in fields {
+ if field.attrs.backtrace.is_some() {
+ return Some(field);
+ }
+ }
+ for field in fields {
+ if field.is_backtrace() {
+ return Some(field);
+ }
+ }
+ None
+}
+
+// The #[backtrace] field, if it is not the same as the #[from] field.
+fn distinct_backtrace_field<'a, 'b>(
+ backtrace_field: &'a Field<'b>,
+ from_field: Option<&Field>,
+) -> Option<&'a Field<'b>> {
+ if from_field.map_or(false, |from_field| {
+ from_field.member == backtrace_field.member
+ }) {
+ None
+ } else {
+ Some(backtrace_field)
+ }
+}
+
+fn type_is_backtrace(ty: &Type) -> bool {
+ let path = match ty {
+ Type::Path(ty) => &ty.path,
+ _ => return false,
+ };
+
+ let last = path.segments.last().unwrap();
+ last.ident == "Backtrace" && last.arguments.is_empty()
+}
diff --git a/third_party/rust/thiserror-impl/src/span.rs b/third_party/rust/thiserror-impl/src/span.rs
new file mode 100644
index 0000000000..c1237ddfc5
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/span.rs
@@ -0,0 +1,15 @@
+use proc_macro2::Span;
+use syn::Member;
+
+pub trait MemberSpan {
+ fn member_span(&self) -> Span;
+}
+
+impl MemberSpan for Member {
+ fn member_span(&self) -> Span {
+ match self {
+ Member::Named(ident) => ident.span(),
+ Member::Unnamed(index) => index.span,
+ }
+ }
+}
diff --git a/third_party/rust/thiserror-impl/src/valid.rs b/third_party/rust/thiserror-impl/src/valid.rs
new file mode 100644
index 0000000000..cf5b8592c2
--- /dev/null
+++ b/third_party/rust/thiserror-impl/src/valid.rs
@@ -0,0 +1,237 @@
+use crate::ast::{Enum, Field, Input, Struct, Variant};
+use crate::attr::Attrs;
+use quote::ToTokens;
+use std::collections::BTreeSet as Set;
+use syn::{Error, GenericArgument, Member, PathArguments, Result, Type};
+
+impl Input<'_> {
+ pub(crate) fn validate(&self) -> Result<()> {
+ match self {
+ Input::Struct(input) => input.validate(),
+ Input::Enum(input) => input.validate(),
+ }
+ }
+}
+
+impl Struct<'_> {
+ fn validate(&self) -> Result<()> {
+ check_non_field_attrs(&self.attrs)?;
+ if let Some(transparent) = self.attrs.transparent {
+ if self.fields.len() != 1 {
+ return Err(Error::new_spanned(
+ transparent.original,
+ "#[error(transparent)] requires exactly one field",
+ ));
+ }
+ if let Some(source) = self.fields.iter().find_map(|f| f.attrs.source) {
+ return Err(Error::new_spanned(
+ source,
+ "transparent error struct can't contain #[source]",
+ ));
+ }
+ }
+ check_field_attrs(&self.fields)?;
+ for field in &self.fields {
+ field.validate()?;
+ }
+ Ok(())
+ }
+}
+
+impl Enum<'_> {
+ fn validate(&self) -> Result<()> {
+ check_non_field_attrs(&self.attrs)?;
+ let has_display = self.has_display();
+ for variant in &self.variants {
+ variant.validate()?;
+ if has_display && variant.attrs.display.is_none() && variant.attrs.transparent.is_none()
+ {
+ return Err(Error::new_spanned(
+ variant.original,
+ "missing #[error(\"...\")] display attribute",
+ ));
+ }
+ }
+ let mut from_types = Set::new();
+ for variant in &self.variants {
+ if let Some(from_field) = variant.from_field() {
+ let repr = from_field.ty.to_token_stream().to_string();
+ if !from_types.insert(repr) {
+ return Err(Error::new_spanned(
+ from_field.original,
+ "cannot derive From because another variant has the same source type",
+ ));
+ }
+ }
+ }
+ Ok(())
+ }
+}
+
+impl Variant<'_> {
+ fn validate(&self) -> Result<()> {
+ check_non_field_attrs(&self.attrs)?;
+ if self.attrs.transparent.is_some() {
+ if self.fields.len() != 1 {
+ return Err(Error::new_spanned(
+ self.original,
+ "#[error(transparent)] requires exactly one field",
+ ));
+ }
+ if let Some(source) = self.fields.iter().find_map(|f| f.attrs.source) {
+ return Err(Error::new_spanned(
+ source,
+ "transparent variant can't contain #[source]",
+ ));
+ }
+ }
+ check_field_attrs(&self.fields)?;
+ for field in &self.fields {
+ field.validate()?;
+ }
+ Ok(())
+ }
+}
+
+impl Field<'_> {
+ fn validate(&self) -> Result<()> {
+ if let Some(display) = &self.attrs.display {
+ return Err(Error::new_spanned(
+ display.original,
+ "not expected here; the #[error(...)] attribute belongs on top of a struct or an enum variant",
+ ));
+ }
+ Ok(())
+ }
+}
+
+fn check_non_field_attrs(attrs: &Attrs) -> Result<()> {
+ if let Some(from) = &attrs.from {
+ return Err(Error::new_spanned(
+ from,
+ "not expected here; the #[from] attribute belongs on a specific field",
+ ));
+ }
+ if let Some(source) = &attrs.source {
+ return Err(Error::new_spanned(
+ source,
+ "not expected here; the #[source] attribute belongs on a specific field",
+ ));
+ }
+ if let Some(backtrace) = &attrs.backtrace {
+ return Err(Error::new_spanned(
+ backtrace,
+ "not expected here; the #[backtrace] attribute belongs on a specific field",
+ ));
+ }
+ if let Some(display) = &attrs.display {
+ if attrs.transparent.is_some() {
+ return Err(Error::new_spanned(
+ display.original,
+ "cannot have both #[error(transparent)] and a display attribute",
+ ));
+ }
+ }
+ Ok(())
+}
+
+fn check_field_attrs(fields: &[Field]) -> Result<()> {
+ let mut from_field = None;
+ let mut source_field = None;
+ let mut backtrace_field = None;
+ let mut has_backtrace = false;
+ for field in fields {
+ if let Some(from) = field.attrs.from {
+ if from_field.is_some() {
+ return Err(Error::new_spanned(from, "duplicate #[from] attribute"));
+ }
+ from_field = Some(field);
+ }
+ if let Some(source) = field.attrs.source {
+ if source_field.is_some() {
+ return Err(Error::new_spanned(source, "duplicate #[source] attribute"));
+ }
+ source_field = Some(field);
+ }
+ if let Some(backtrace) = field.attrs.backtrace {
+ if backtrace_field.is_some() {
+ return Err(Error::new_spanned(
+ backtrace,
+ "duplicate #[backtrace] attribute",
+ ));
+ }
+ backtrace_field = Some(field);
+ has_backtrace = true;
+ }
+ if let Some(transparent) = field.attrs.transparent {
+ return Err(Error::new_spanned(
+ transparent.original,
+ "#[error(transparent)] needs to go outside the enum or struct, not on an individual field",
+ ));
+ }
+ has_backtrace |= field.is_backtrace();
+ }
+ if let (Some(from_field), Some(source_field)) = (from_field, source_field) {
+ if !same_member(from_field, source_field) {
+ return Err(Error::new_spanned(
+ from_field.attrs.from,
+ "#[from] is only supported on the source field, not any other field",
+ ));
+ }
+ }
+ if let Some(from_field) = from_field {
+ let max_expected_fields = match backtrace_field {
+ Some(backtrace_field) => 1 + !same_member(from_field, backtrace_field) as usize,
+ None => 1 + has_backtrace as usize,
+ };
+ if fields.len() > max_expected_fields {
+ return Err(Error::new_spanned(
+ from_field.attrs.from,
+ "deriving From requires no fields other than source and backtrace",
+ ));
+ }
+ }
+ if let Some(source_field) = source_field.or(from_field) {
+ if contains_non_static_lifetime(source_field.ty) {
+ return Err(Error::new_spanned(
+ &source_field.original.ty,
+ "non-static lifetimes are not allowed in the source of an error, because std::error::Error requires the source is dyn Error + 'static",
+ ));
+ }
+ }
+ Ok(())
+}
+
+fn same_member(one: &Field, two: &Field) -> bool {
+ match (&one.member, &two.member) {
+ (Member::Named(one), Member::Named(two)) => one == two,
+ (Member::Unnamed(one), Member::Unnamed(two)) => one.index == two.index,
+ _ => unreachable!(),
+ }
+}
+
+fn contains_non_static_lifetime(ty: &Type) -> bool {
+ match ty {
+ Type::Path(ty) => {
+ let bracketed = match &ty.path.segments.last().unwrap().arguments {
+ PathArguments::AngleBracketed(bracketed) => bracketed,
+ _ => return false,
+ };
+ for arg in &bracketed.args {
+ match arg {
+ GenericArgument::Type(ty) if contains_non_static_lifetime(ty) => return true,
+ GenericArgument::Lifetime(lifetime) if lifetime.ident != "static" => {
+ return true
+ }
+ _ => {}
+ }
+ }
+ false
+ }
+ Type::Reference(ty) => ty
+ .lifetime
+ .as_ref()
+ .map_or(false, |lifetime| lifetime.ident != "static"),
+ _ => false, // maybe implement later if there are common other cases
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 15:24:37 +0000