diff options
Diffstat (limited to 'compiler/rustc_macros/src/diagnostics')
| -rw-r--r-- | compiler/rustc_macros/src/diagnostics/diagnostic.rs | 586 | ||||
| -rw-r--r-- | compiler/rustc_macros/src/diagnostics/error.rs | 132 | ||||
| -rw-r--r-- | compiler/rustc_macros/src/diagnostics/mod.rs | 114 | ||||
| -rw-r--r-- | compiler/rustc_macros/src/diagnostics/subdiagnostic.rs | 437 | ||||
| -rw-r--r-- | compiler/rustc_macros/src/diagnostics/utils.rs | 267 |
5 files changed, 1536 insertions, 0 deletions
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs new file mode 100644 index 00000000000..f49166433fa --- /dev/null +++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs @@ -0,0 +1,586 @@ +#![deny(unused_must_use)] + +use crate::diagnostics::error::{ + invalid_nested_attr, span_err, throw_invalid_attr, throw_invalid_nested_attr, throw_span_err, + SessionDiagnosticDeriveError, +}; +use crate::diagnostics::utils::{ + option_inner_ty, report_error_if_not_applied_to_span, type_matches_path, Applicability, + FieldInfo, HasFieldMap, SetOnce, +}; +use proc_macro2::TokenStream; +use quote::{format_ident, quote}; +use std::collections::HashMap; +use std::str::FromStr; +use syn::{spanned::Spanned, Attribute, Meta, MetaList, MetaNameValue, Type}; +use synstructure::Structure; + +/// The central struct for constructing the `into_diagnostic` method from an annotated struct. +pub(crate) struct SessionDiagnosticDerive<'a> { + structure: Structure<'a>, + builder: SessionDiagnosticDeriveBuilder, +} + +impl<'a> SessionDiagnosticDerive<'a> { + pub(crate) fn new(diag: syn::Ident, sess: syn::Ident, structure: Structure<'a>) -> Self { + // Build the mapping of field names to fields. This allows attributes to peek values from + // other fields. + let mut fields_map = HashMap::new(); + + // Convenience bindings. + let ast = structure.ast(); + + if let syn::Data::Struct(syn::DataStruct { fields, .. }) = &ast.data { + for field in fields.iter() { + if let Some(ident) = &field.ident { + fields_map.insert(ident.to_string(), quote! { &self.#ident }); + } + } + } + + Self { + builder: SessionDiagnosticDeriveBuilder { + diag, + sess, + fields: fields_map, + kind: None, + code: None, + slug: None, + }, + structure, + } + } + + pub(crate) fn into_tokens(self) -> TokenStream { + let SessionDiagnosticDerive { mut structure, mut builder } = self; + + let ast = structure.ast(); + let attrs = &ast.attrs; + + let (implementation, param_ty) = { + if let syn::Data::Struct(..) = ast.data { + let preamble = { + let preamble = attrs.iter().map(|attr| { + builder + .generate_structure_code(attr) + .unwrap_or_else(|v| v.to_compile_error()) + }); + + quote! { + #(#preamble)*; + } + }; + + // Generates calls to `span_label` and similar functions based on the attributes + // on fields. Code for suggestions uses formatting machinery and the value of + // other fields - because any given field can be referenced multiple times, it + // should be accessed through a borrow. When passing fields to `set_arg` (which + // happens below) for Fluent, we want to move the data, so that has to happen + // in a separate pass over the fields. + let attrs = structure.each(|field_binding| { + let field = field_binding.ast(); + let result = field.attrs.iter().map(|attr| { + builder + .generate_field_attr_code( + attr, + FieldInfo { + vis: &field.vis, + binding: field_binding, + ty: &field.ty, + span: &field.span(), + }, + ) + .unwrap_or_else(|v| v.to_compile_error()) + }); + + quote! { #(#result);* } + }); + + // When generating `set_arg` calls, move data rather than borrow it to avoid + // requiring clones - this must therefore be the last use of each field (for + // example, any formatting machinery that might refer to a field should be + // generated already). + structure.bind_with(|_| synstructure::BindStyle::Move); + let args = structure.each(|field_binding| { + let field = field_binding.ast(); + // When a field has attributes like `#[label]` or `#[note]` then it doesn't + // need to be passed as an argument to the diagnostic. But when a field has no + // attributes then it must be passed as an argument to the diagnostic so that + // it can be referred to by Fluent messages. + if field.attrs.is_empty() { + let diag = &builder.diag; + let ident = field_binding.ast().ident.as_ref().unwrap(); + quote! { + #diag.set_arg( + stringify!(#ident), + #field_binding.into_diagnostic_arg() + ); + } + } else { + quote! {} + } + }); + + let span = ast.span().unwrap(); + let (diag, sess) = (&builder.diag, &builder.sess); + let init = match (builder.kind, builder.slug) { + (None, _) => { + span_err(span, "diagnostic kind not specified") + .help("use the `#[error(...)]` attribute to create an error") + .emit(); + return SessionDiagnosticDeriveError::ErrorHandled.to_compile_error(); + } + (Some((kind, _)), None) => { + span_err(span, "`slug` not specified") + .help(&format!("use the `#[{}(slug = \"...\")]` attribute to set this diagnostic's slug", kind.descr())) + .emit(); + return SessionDiagnosticDeriveError::ErrorHandled.to_compile_error(); + } + (Some((SessionDiagnosticKind::Error, _)), Some((slug, _))) => { + quote! { + let mut #diag = #sess.struct_err( + rustc_errors::DiagnosticMessage::fluent(#slug), + ); + } + } + (Some((SessionDiagnosticKind::Warn, _)), Some((slug, _))) => { + quote! { + let mut #diag = #sess.struct_warn( + rustc_errors::DiagnosticMessage::fluent(#slug), + ); + } + } + }; + + let implementation = quote! { + #init + #preamble + match self { + #attrs + } + match self { + #args + } + #diag + }; + let param_ty = match builder.kind { + Some((SessionDiagnosticKind::Error, _)) => { + quote! { rustc_errors::ErrorGuaranteed } + } + Some((SessionDiagnosticKind::Warn, _)) => quote! { () }, + _ => unreachable!(), + }; + + (implementation, param_ty) + } else { + span_err( + ast.span().unwrap(), + "`#[derive(SessionDiagnostic)]` can only be used on structs", + ) + .emit(); + + let implementation = SessionDiagnosticDeriveError::ErrorHandled.to_compile_error(); + let param_ty = quote! { rustc_errors::ErrorGuaranteed }; + (implementation, param_ty) + } + }; + + let sess = &builder.sess; + structure.gen_impl(quote! { + gen impl<'__session_diagnostic_sess> rustc_session::SessionDiagnostic<'__session_diagnostic_sess, #param_ty> + for @Self + { + fn into_diagnostic( + self, + #sess: &'__session_diagnostic_sess rustc_session::parse::ParseSess + ) -> rustc_errors::DiagnosticBuilder<'__session_diagnostic_sess, #param_ty> { + use rustc_errors::IntoDiagnosticArg; + #implementation + } + } + }) + } +} + +/// What kind of session diagnostic is being derived - an error or a warning? +#[derive(Copy, Clone)] +enum SessionDiagnosticKind { + /// `#[error(..)]` + Error, + /// `#[warn(..)]` + Warn, +} + +impl SessionDiagnosticKind { + /// Returns human-readable string corresponding to the kind. + fn descr(&self) -> &'static str { + match self { + SessionDiagnosticKind::Error => "error", + SessionDiagnosticKind::Warn => "warning", + } + } +} + +/// Tracks persistent information required for building up the individual calls to diagnostic +/// methods for the final generated method. This is a separate struct to `SessionDiagnosticDerive` +/// only to be able to destructure and split `self.builder` and the `self.structure` up to avoid a +/// double mut borrow later on. +struct SessionDiagnosticDeriveBuilder { + /// Name of the session parameter that's passed in to the `as_error` method. + sess: syn::Ident, + /// The identifier to use for the generated `DiagnosticBuilder` instance. + diag: syn::Ident, + + /// Store a map of field name to its corresponding field. This is built on construction of the + /// derive builder. + fields: HashMap<String, TokenStream>, + + /// Kind of diagnostic requested via the struct attribute. + kind: Option<(SessionDiagnosticKind, proc_macro::Span)>, + /// Slug is a mandatory part of the struct attribute as corresponds to the Fluent message that + /// has the actual diagnostic message. + slug: Option<(String, proc_macro::Span)>, + /// Error codes are a optional part of the struct attribute - this is only set to detect + /// multiple specifications. + code: Option<(String, proc_macro::Span)>, +} + +impl HasFieldMap for SessionDiagnosticDeriveBuilder { + fn get_field_binding(&self, field: &String) -> Option<&TokenStream> { + self.fields.get(field) + } +} + +impl SessionDiagnosticDeriveBuilder { + /// Establishes state in the `SessionDiagnosticDeriveBuilder` resulting from the struct + /// attributes like `#[error(..)#`, such as the diagnostic kind and slug. Generates + /// diagnostic builder calls for setting error code and creating note/help messages. + fn generate_structure_code( + &mut self, + attr: &Attribute, + ) -> Result<TokenStream, SessionDiagnosticDeriveError> { + let span = attr.span().unwrap(); + + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + let meta = attr.parse_meta()?; + + if matches!(name, "help" | "note") && matches!(meta, Meta::Path(_) | Meta::NameValue(_)) { + let diag = &self.diag; + let slug = match &self.slug { + Some((slug, _)) => slug.as_str(), + None => throw_span_err!( + span, + &format!( + "`#[{}{}]` must come after `#[error(..)]` or `#[warn(..)]`", + name, + match meta { + Meta::Path(_) => "", + Meta::NameValue(_) => " = ...", + _ => unreachable!(), + } + ) + ), + }; + let id = match meta { + Meta::Path(..) => quote! { #name }, + Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => { + quote! { #s } + } + _ => unreachable!(), + }; + let fn_name = proc_macro2::Ident::new(name, attr.span()); + + return Ok(quote! { + #diag.#fn_name(rustc_errors::DiagnosticMessage::fluent_attr(#slug, #id)); + }); + } + + let nested = match meta { + Meta::List(MetaList { ref nested, .. }) => nested, + _ => throw_invalid_attr!(attr, &meta), + }; + + let kind = match name { + "error" => SessionDiagnosticKind::Error, + "warning" => SessionDiagnosticKind::Warn, + _ => throw_invalid_attr!(attr, &meta, |diag| { + diag.help("only `error` and `warning` are valid attributes") + }), + }; + self.kind.set_once((kind, span)); + + let mut tokens = Vec::new(); + for nested_attr in nested { + let meta = match nested_attr { + syn::NestedMeta::Meta(meta) => meta, + _ => throw_invalid_nested_attr!(attr, &nested_attr), + }; + + let path = meta.path(); + let nested_name = path.segments.last().unwrap().ident.to_string(); + match &meta { + // Struct attributes are only allowed to be applied once, and the diagnostic + // changes will be set in the initialisation code. + Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => { + let span = s.span().unwrap(); + match nested_name.as_str() { + "slug" => { + self.slug.set_once((s.value(), span)); + } + "code" => { + self.code.set_once((s.value(), span)); + let (diag, code) = (&self.diag, &self.code.as_ref().map(|(v, _)| v)); + tokens.push(quote! { + #diag.code(rustc_errors::DiagnosticId::Error(#code.to_string())); + }); + } + _ => invalid_nested_attr(attr, &nested_attr) + .help("only `slug` and `code` are valid nested attributes") + .emit(), + } + } + _ => invalid_nested_attr(attr, &nested_attr).emit(), + } + } + + Ok(tokens.drain(..).collect()) + } + + fn generate_field_attr_code( + &mut self, + attr: &syn::Attribute, + info: FieldInfo<'_>, + ) -> Result<TokenStream, SessionDiagnosticDeriveError> { + let field_binding = &info.binding.binding; + let option_ty = option_inner_ty(&info.ty); + let generated_code = self.generate_non_option_field_code( + attr, + FieldInfo { + vis: info.vis, + binding: info.binding, + ty: option_ty.unwrap_or(&info.ty), + span: info.span, + }, + )?; + + if option_ty.is_none() { + Ok(quote! { #generated_code }) + } else { + Ok(quote! { + if let Some(#field_binding) = #field_binding { + #generated_code + } + }) + } + } + + fn generate_non_option_field_code( + &mut self, + attr: &Attribute, + info: FieldInfo<'_>, + ) -> Result<TokenStream, SessionDiagnosticDeriveError> { + let diag = &self.diag; + let field_binding = &info.binding.binding; + + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + + let meta = attr.parse_meta()?; + match meta { + Meta::Path(_) => match name { + "skip_arg" => { + // Don't need to do anything - by virtue of the attribute existing, the + // `set_arg` call will not be generated. + Ok(quote! {}) + } + "primary_span" => { + report_error_if_not_applied_to_span(attr, &info)?; + Ok(quote! { + #diag.set_span(*#field_binding); + }) + } + "label" | "note" | "help" => { + report_error_if_not_applied_to_span(attr, &info)?; + Ok(self.add_subdiagnostic(field_binding, name, name)) + } + "subdiagnostic" => Ok(quote! { #diag.subdiagnostic(*#field_binding); }), + _ => throw_invalid_attr!(attr, &meta, |diag| { + diag + .help("only `skip_arg`, `primary_span`, `label`, `note`, `help` and `subdiagnostic` are valid field attributes") + }), + }, + Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(ref s), .. }) => match name { + "label" | "note" | "help" => { + report_error_if_not_applied_to_span(attr, &info)?; + Ok(self.add_subdiagnostic(field_binding, name, &s.value())) + } + _ => throw_invalid_attr!(attr, &meta, |diag| { + diag.help("only `label`, `note` and `help` are valid field attributes") + }), + }, + Meta::List(MetaList { ref path, ref nested, .. }) => { + let name = path.segments.last().unwrap().ident.to_string(); + let name = name.as_ref(); + + match name { + "suggestion" | "suggestion_short" | "suggestion_hidden" + | "suggestion_verbose" => (), + _ => throw_invalid_attr!(attr, &meta, |diag| { + diag + .help("only `suggestion{,_short,_hidden,_verbose}` are valid field attributes") + }), + }; + + let (span_field, mut applicability) = self.span_and_applicability_of_ty(info)?; + + let mut msg = None; + let mut code = None; + + for nested_attr in nested { + let meta = match nested_attr { + syn::NestedMeta::Meta(ref meta) => meta, + syn::NestedMeta::Lit(_) => throw_invalid_nested_attr!(attr, &nested_attr), + }; + + let nested_name = meta.path().segments.last().unwrap().ident.to_string(); + let nested_name = nested_name.as_str(); + match meta { + Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => { + let span = meta.span().unwrap(); + match nested_name { + "message" => { + msg = Some(s.value()); + } + "code" => { + let formatted_str = self.build_format(&s.value(), s.span()); + code = Some(formatted_str); + } + "applicability" => { + applicability = match applicability { + Some(v) => { + span_err( + span, + "applicability cannot be set in both the field and attribute" + ).emit(); + Some(v) + } + None => match Applicability::from_str(&s.value()) { + Ok(v) => Some(quote! { #v }), + Err(()) => { + span_err(span, "invalid applicability").emit(); + None + } + }, + } + } + _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| { + diag.help( + "only `message`, `code` and `applicability` are valid field attributes", + ) + }), + } + } + _ => throw_invalid_nested_attr!(attr, &nested_attr), + } + } + + let applicability = applicability + .unwrap_or_else(|| quote!(rustc_errors::Applicability::Unspecified)); + + let method = format_ident!("span_{}", name); + + let slug = self + .slug + .as_ref() + .map(|(slug, _)| slug.as_str()) + .unwrap_or_else(|| "missing-slug"); + let msg = msg.as_deref().unwrap_or("suggestion"); + let msg = quote! { rustc_errors::DiagnosticMessage::fluent_attr(#slug, #msg) }; + let code = code.unwrap_or_else(|| quote! { String::new() }); + + Ok(quote! { #diag.#method(#span_field, #msg, #code, #applicability); }) + } + _ => throw_invalid_attr!(attr, &meta), + } + } + + /// Adds a subdiagnostic by generating a `diag.span_$kind` call with the current slug and + /// `fluent_attr_identifier`. + fn add_subdiagnostic( + &self, + field_binding: &proc_macro2::Ident, + kind: &str, + fluent_attr_identifier: &str, + ) -> TokenStream { + let diag = &self.diag; + + let slug = + self.slug.as_ref().map(|(slug, _)| slug.as_str()).unwrap_or_else(|| "missing-slug"); + let fn_name = format_ident!("span_{}", kind); + quote! { + #diag.#fn_name( + *#field_binding, + rustc_errors::DiagnosticMessage::fluent_attr(#slug, #fluent_attr_identifier) + ); + } + } + + fn span_and_applicability_of_ty( + &self, + info: FieldInfo<'_>, + ) -> Result<(TokenStream, Option<TokenStream>), SessionDiagnosticDeriveError> { + match &info.ty { + // If `ty` is `Span` w/out applicability, then use `Applicability::Unspecified`. + ty @ Type::Path(..) if type_matches_path(ty, &["rustc_span", "Span"]) => { + let binding = &info.binding.binding; + Ok((quote!(*#binding), None)) + } + // If `ty` is `(Span, Applicability)` then return tokens accessing those. + Type::Tuple(tup) => { + let mut span_idx = None; + let mut applicability_idx = None; + + for (idx, elem) in tup.elems.iter().enumerate() { + if type_matches_path(elem, &["rustc_span", "Span"]) { + if span_idx.is_none() { + span_idx = Some(syn::Index::from(idx)); + } else { + throw_span_err!( + info.span.unwrap(), + "type of field annotated with `#[suggestion(...)]` contains more than one `Span`" + ); + } + } else if type_matches_path(elem, &["rustc_errors", "Applicability"]) { + if applicability_idx.is_none() { + applicability_idx = Some(syn::Index::from(idx)); + } else { + throw_span_err!( + info.span.unwrap(), + "type of field annotated with `#[suggestion(...)]` contains more than one Applicability" + ); + } + } + } + + if let Some(span_idx) = span_idx { + let binding = &info.binding.binding; + let span = quote!(#binding.#span_idx); + let applicability = applicability_idx + .map(|applicability_idx| quote!(#binding.#applicability_idx)) + .unwrap_or_else(|| quote!(rustc_errors::Applicability::Unspecified)); + + return Ok((span, Some(applicability))); + } + + throw_span_err!(info.span.unwrap(), "wrong types for suggestion", |diag| { + diag.help("`#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`") + }); + } + // If `ty` isn't a `Span` or `(Span, Applicability)` then emit an error. + _ => throw_span_err!(info.span.unwrap(), "wrong field type for suggestion", |diag| { + diag.help("`#[suggestion(...)]` should be applied to fields of type `Span` or `(Span, Applicability)`") + }), + } + } +} diff --git a/compiler/rustc_macros/src/diagnostics/error.rs b/compiler/rustc_macros/src/diagnostics/error.rs new file mode 100644 index 00000000000..fd1dc2f3073 --- /dev/null +++ b/compiler/rustc_macros/src/diagnostics/error.rs @@ -0,0 +1,132 @@ +use proc_macro::{Diagnostic, Level, MultiSpan}; +use proc_macro2::TokenStream; +use quote::quote; +use syn::{spanned::Spanned, Attribute, Error as SynError, Meta, NestedMeta}; + +#[derive(Debug)] +pub(crate) enum SessionDiagnosticDeriveError { + SynError(SynError), + ErrorHandled, +} + +impl SessionDiagnosticDeriveError { + pub(crate) fn to_compile_error(self) -> TokenStream { + match self { + SessionDiagnosticDeriveError::SynError(e) => e.to_compile_error(), + SessionDiagnosticDeriveError::ErrorHandled => { + // Return ! to avoid having to create a blank DiagnosticBuilder to return when an + // error has already been emitted to the compiler. + quote! { + { unreachable!(); } + } + } + } + } +} + +impl From<SynError> for SessionDiagnosticDeriveError { + fn from(e: SynError) -> Self { + SessionDiagnosticDeriveError::SynError(e) + } +} + +/// Helper function for use with `throw_*` macros - constraints `$f` to an `impl FnOnce`. +pub(crate) fn _throw_err( + diag: Diagnostic, + f: impl FnOnce(Diagnostic) -> Diagnostic, +) -> SessionDiagnosticDeriveError { + f(diag).emit(); + SessionDiagnosticDeriveError::ErrorHandled +} + +/// Returns an error diagnostic on span `span` with msg `msg`. +pub(crate) fn span_err(span: impl MultiSpan, msg: &str) -> Diagnostic { + Diagnostic::spanned(span, Level::Error, msg) +} + +/// Emit a diagnostic on span `$span` with msg `$msg` (optionally performing additional decoration +/// using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`. +/// +/// For methods that return a `Result<_, SessionDiagnosticDeriveError>`: +macro_rules! throw_span_err { + ($span:expr, $msg:expr) => {{ throw_span_err!($span, $msg, |diag| diag) }}; + ($span:expr, $msg:expr, $f:expr) => {{ + let diag = span_err($span, $msg); + return Err(crate::diagnostics::error::_throw_err(diag, $f)); + }}; +} + +pub(crate) use throw_span_err; + +/// Returns an error diagnostic for an invalid attribute. +pub(crate) fn invalid_attr(attr: &Attribute, meta: &Meta) -> Diagnostic { + let span = attr.span().unwrap(); + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + + match meta { + Meta::Path(_) => span_err(span, &format!("`#[{}]` is not a valid attribute", name)), + Meta::NameValue(_) => { + span_err(span, &format!("`#[{} = ...]` is not a valid attribute", name)) + } + Meta::List(_) => span_err(span, &format!("`#[{}(...)]` is not a valid attribute", name)), + } +} + +/// Emit a error diagnostic for an invalid attribute (optionally performing additional decoration +/// using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`. +/// +/// For methods that return a `Result<_, SessionDiagnosticDeriveError>`: +macro_rules! throw_invalid_attr { + ($attr:expr, $meta:expr) => {{ throw_invalid_attr!($attr, $meta, |diag| diag) }}; + ($attr:expr, $meta:expr, $f:expr) => {{ + let diag = crate::diagnostics::error::invalid_attr($attr, $meta); + return Err(crate::diagnostics::error::_throw_err(diag, $f)); + }}; +} + +pub(crate) use throw_invalid_attr; + +/// Returns an error diagnostic for an invalid nested attribute. +pub(crate) fn invalid_nested_attr(attr: &Attribute, nested: &NestedMeta) -> Diagnostic { + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + + let span = nested.span().unwrap(); + let meta = match nested { + syn::NestedMeta::Meta(meta) => meta, + syn::NestedMeta::Lit(_) => { + return span_err(span, &format!("`#[{}(\"...\")]` is not a valid attribute", name)); + } + }; + + let span = meta.span().unwrap(); + let nested_name = meta.path().segments.last().unwrap().ident.to_string(); + let nested_name = nested_name.as_str(); + match meta { + Meta::NameValue(..) => span_err( + span, + &format!("`#[{}({} = ...)]` is not a valid attribute", name, nested_name), + ), + Meta::Path(..) => { + span_err(span, &format!("`#[{}({})]` is not a valid attribute", name, nested_name)) + } + Meta::List(..) => { + span_err(span, &format!("`#[{}({}(...))]` is not a valid attribute", name, nested_name)) + } + } +} + +/// Emit a error diagnostic for an invalid nested attribute (optionally performing additional +/// decoration using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`. +/// +/// For methods that return a `Result<_, SessionDiagnosticDeriveError>`: +macro_rules! throw_invalid_nested_attr { + ($attr:expr, $nested_attr:expr) => {{ throw_invalid_nested_attr!($attr, $nested_attr, |diag| diag) }}; + ($attr:expr, $nested_attr:expr, $f:expr) => {{ + let diag = crate::diagnostics::error::invalid_nested_attr($attr, $nested_attr); + return Err(crate::diagnostics::error::_throw_err(diag, $f)); + }}; +} + +pub(crate) use throw_invalid_nested_attr; diff --git a/compiler/rustc_macros/src/diagnostics/mod.rs b/compiler/rustc_macros/src/diagnostics/mod.rs new file mode 100644 index 00000000000..73ad415d6c3 --- /dev/null +++ b/compiler/rustc_macros/src/diagnostics/mod.rs @@ -0,0 +1,114 @@ +mod diagnostic; +mod error; +mod subdiagnostic; +mod utils; + +use diagnostic::SessionDiagnosticDerive; +use proc_macro2::TokenStream; +use quote::format_ident; +use subdiagnostic::SessionSubdiagnosticDerive; +use synstructure::Structure; + +/// Implements `#[derive(SessionDiagnostic)]`, which allows for errors to be specified as a struct, +/// independent from the actual diagnostics emitting code. +/// +/// ```ignore (pseudo-rust) +/// # extern crate rustc_errors; +/// # use rustc_errors::Applicability; +/// # extern crate rustc_span; +/// # use rustc_span::{symbol::Ident, Span}; +/// # extern crate rust_middle; +/// # use rustc_middle::ty::Ty; +/// #[derive(SessionDiagnostic)] +/// #[error(code = "E0505", slug = "borrowck-move-out-of-borrow")] +/// pub struct MoveOutOfBorrowError<'tcx> { +/// pub name: Ident, +/// pub ty: Ty<'tcx>, +/// #[primary_span] +/// #[label] +/// pub span: Span, +/// #[label = "first-borrow-label"] +/// pub first_borrow_span: Span, +/// #[suggestion(code = "{name}.clone()")] +/// pub clone_sugg: Option<(Span, Applicability)> +/// } +/// ``` +/// +/// ```fluent +/// move-out-of-borrow = cannot move out of {$name} because it is borrowed +/// .label = cannot move out of borrow +/// .first-borrow-label = `{$ty}` first borrowed here +/// .suggestion = consider cloning here +/// ``` +/// +/// Then, later, to emit the error: +/// +/// ```ignore (pseudo-rust) +/// sess.emit_err(MoveOutOfBorrowError { +/// expected, +/// actual, +/// span, +/// first_borrow_span, +/// clone_sugg: Some(suggestion, Applicability::MachineApplicable), +/// }); +/// ``` +/// +/// See rustc dev guide for more examples on using the `#[derive(SessionDiagnostic)]`: +/// <https://rustc-dev-guide.rust-lang.org/diagnostics/sessiondiagnostic.html> +pub fn session_diagnostic_derive(s: Structure<'_>) -> TokenStream { + // Names for the diagnostic we build and the session we build it from. + let diag = format_ident!("diag"); + let sess = format_ident!("sess"); + + SessionDiagnosticDerive::new(diag, sess, s).into_tokens() +} + +/// Implements `#[derive(SessionSubdiagnostic)]`, which allows for labels, notes, helps and +/// suggestions to be specified as a structs or enums, independent from the actual diagnostics +/// emitting code or diagnostic derives. +/// +/// ```ignore (pseudo-rust) +/// #[derive(SessionSubdiagnostic)] +/// pub enum ExpectedIdentifierLabel<'tcx> { +/// #[label(slug = "parser-expected-identifier")] +/// WithoutFound { +/// #[primary_span] +/// span: Span, +/// } +/// #[label(slug = "parser-expected-identifier-found")] +/// WithFound { +/// #[primary_span] +/// span: Span, +/// found: String, +/// } +/// } +/// +/// #[derive(SessionSubdiagnostic)] +/// #[suggestion_verbose(slug = "parser-raw-identifier")] +/// pub struct RawIdentifierSuggestion<'tcx> { +/// #[primary_span] +/// span: Span, +/// #[applicability] +/// applicability: Applicability, +/// ident: Ident, +/// } +/// ``` +/// +/// ```fluent +/// parser-expected-identifier = expected identifier +/// +/// parser-expected-identifier-found = expected identifier, found {$found} +/// +/// parser-raw-identifier = escape `{$ident}` to use it as an identifier +/// ``` +/// +/// Then, later, to add the subdiagnostic: +/// +/// ```ignore (pseudo-rust) +/// diag.subdiagnostic(ExpectedIdentifierLabel::WithoutFound { span }); +/// +/// diag.subdiagnostic(RawIdentifierSuggestion { span, applicability, ident }); +/// ``` +pub fn session_subdiagnostic_derive(s: Structure<'_>) -> TokenStream { + SessionSubdiagnosticDerive::new(s).into_tokens() +} diff --git a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs new file mode 100644 index 00000000000..961b42f424f --- /dev/null +++ b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs @@ -0,0 +1,437 @@ +#![deny(unused_must_use)] + +use crate::diagnostics::error::{ + span_err, throw_invalid_attr, throw_invalid_nested_attr, throw_span_err, + SessionDiagnosticDeriveError, +}; +use crate::diagnostics::utils::{ + option_inner_ty, report_error_if_not_applied_to_applicability, + report_error_if_not_applied_to_span, Applicability, FieldInfo, HasFieldMap, SetOnce, +}; +use proc_macro2::TokenStream; +use quote::{format_ident, quote}; +use std::collections::HashMap; +use std::fmt; +use std::str::FromStr; +use syn::{spanned::Spanned, Meta, MetaList, MetaNameValue}; +use synstructure::{BindingInfo, Structure, VariantInfo}; + +/// Which kind of suggestion is being created? +#[derive(Clone, Copy)] +enum SubdiagnosticSuggestionKind { + /// `#[suggestion]` + Normal, + /// `#[suggestion_short]` + Short, + /// `#[suggestion_hidden]` + Hidden, + /// `#[suggestion_verbose]` + Verbose, +} + +/// Which kind of subdiagnostic is being created from a variant? +#[derive(Clone, Copy)] +enum SubdiagnosticKind { + /// `#[label(...)]` + Label, + /// `#[note(...)]` + Note, + /// `#[help(...)]` + Help, + /// `#[suggestion{,_short,_hidden,_verbose}]` + Suggestion(SubdiagnosticSuggestionKind), +} + +impl FromStr for SubdiagnosticKind { + type Err = (); + + fn from_str(s: &str) -> Result<Self, Self::Err> { + match s { + "label" => Ok(SubdiagnosticKind::Label), + "note" => Ok(SubdiagnosticKind::Note), + "help" => Ok(SubdiagnosticKind::Help), + "suggestion" => Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Normal)), + "suggestion_short" => { + Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Short)) + } + "suggestion_hidden" => { + Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Hidden)) + } + "suggestion_verbose" => { + Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Verbose)) + } + _ => Err(()), + } + } +} + +impl quote::IdentFragment for SubdiagnosticKind { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + SubdiagnosticKind::Label => write!(f, "label"), + SubdiagnosticKind::Note => write!(f, "note"), + SubdiagnosticKind::Help => write!(f, "help"), + SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Normal) => { + write!(f, "suggestion") + } + SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Short) => { + write!(f, "suggestion_short") + } + SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Hidden) => { + write!(f, "suggestion_hidden") + } + SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Verbose) => { + write!(f, "suggestion_verbose") + } + } + } + + fn span(&self) -> Option<proc_macro2::Span> { + None + } +} + +/// The central struct for constructing the `add_to_diagnostic` method from an annotated struct. +pub(crate) struct SessionSubdiagnosticDerive<'a> { + structure: Structure<'a>, + diag: syn::Ident, +} + +impl<'a> SessionSubdiagnosticDerive<'a> { + pub(crate) fn new(structure: Structure<'a>) -> Self { + let diag = format_ident!("diag"); + Self { structure, diag } + } + + pub(crate) fn into_tokens(self) -> TokenStream { + let SessionSubdiagnosticDerive { mut structure, diag } = self; + let implementation = { + let ast = structure.ast(); + let span = ast.span().unwrap(); + match ast.data { + syn::Data::Struct(..) | syn::Data::Enum(..) => (), + syn::Data::Union(..) => { + span_err( + span, + "`#[derive(SessionSubdiagnostic)]` can only be used on structs and enums", + ); + } + } + + if matches!(ast.data, syn::Data::Enum(..)) { + for attr in &ast.attrs { + span_err( + attr.span().unwrap(), + "unsupported type attribute for subdiagnostic enum", + ) + .emit(); + } + } + + structure.bind_with(|_| synstructure::BindStyle::Move); + let variants_ = structure.each_variant(|variant| { + // Build the mapping of field names to fields. This allows attributes to peek + // values from other fields. + let mut fields_map = HashMap::new(); + for binding in variant.bindings() { + let field = binding.ast(); + if let Some(ident) = &field.ident { + fields_map.insert(ident.to_string(), quote! { #binding }); + } + } + + let mut builder = SessionSubdiagnosticDeriveBuilder { + diag: &diag, + variant, + span, + fields: fields_map, + kind: None, + slug: None, + code: None, + span_field: None, + applicability: None, + }; + builder.into_tokens().unwrap_or_else(|v| v.to_compile_error()) + }); + + quote! { + match self { + #variants_ + } + } + }; + + let ret = structure.gen_impl(quote! { + gen impl rustc_errors::AddSubdiagnostic for @Self { + fn add_to_diagnostic(self, #diag: &mut rustc_errors::Diagnostic) { + use rustc_errors::{Applicability, IntoDiagnosticArg}; + #implementation + } + } + }); + ret + } +} + +/// Tracks persistent information required for building up the call to add to the diagnostic +/// for the final generated method. This is a separate struct to `SessionSubdiagnosticDerive` +/// only to be able to destructure and split `self.builder` and the `self.structure` up to avoid a +/// double mut borrow later on. +struct SessionSubdiagnosticDeriveBuilder<'a> { + /// The identifier to use for the generated `DiagnosticBuilder` instance. + diag: &'a syn::Ident, + + /// Info for the current variant (or the type if not an enum). + variant: &'a VariantInfo<'a>, + /// Span for the entire type. + span: proc_macro::Span, + + /// Store a map of field name to its corresponding field. This is built on construction of the + /// derive builder. + fields: HashMap<String, TokenStream>, + + /// Subdiagnostic kind of the type/variant. + kind: Option<(SubdiagnosticKind, proc_macro::Span)>, + + /// Slug of the subdiagnostic - corresponds to the Fluent identifier for the message - from the + /// `#[kind(slug = "...")]` attribute on the type or variant. + slug: Option<(String, proc_macro::Span)>, + /// If a suggestion, the code to suggest as a replacement - from the `#[kind(code = "...")]` + /// attribute on the type or variant. + code: Option<(TokenStream, proc_macro::Span)>, + + /// Identifier for the binding to the `#[primary_span]` field. + span_field: Option<(proc_macro2::Ident, proc_macro::Span)>, + /// If a suggestion, the identifier for the binding to the `#[applicability]` field or a + /// `rustc_errors::Applicability::*` variant directly. + applicability: Option<(TokenStream, proc_macro::Span)>, +} + +impl<'a> HasFieldMap for SessionSubdiagnosticDeriveBuilder<'a> { + fn get_field_binding(&self, field: &String) -> Option<&TokenStream> { + self.fields.get(field) + } +} + +impl<'a> SessionSubdiagnosticDeriveBuilder<'a> { + fn identify_kind(&mut self) -> Result<(), SessionDiagnosticDeriveError> { + for attr in self.variant.ast().attrs { + let span = attr.span().unwrap(); + + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + + let meta = attr.parse_meta()?; + let kind = match meta { + Meta::List(MetaList { ref nested, .. }) => { + for nested_attr in nested { + let meta = match nested_attr { + syn::NestedMeta::Meta(ref meta) => meta, + _ => throw_invalid_nested_attr!(attr, &nested_attr), + }; + + let span = meta.span().unwrap(); + let nested_name = meta.path().segments.last().unwrap().ident.to_string(); + let nested_name = nested_name.as_str(); + + match meta { + Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => { + match nested_name { + "code" => { + let formatted_str = self.build_format(&s.value(), s.span()); + self.code.set_once((formatted_str, span)); + } + "slug" => self.slug.set_once((s.value(), span)), + "applicability" => { + let value = match Applicability::from_str(&s.value()) { + Ok(v) => v, + Err(()) => { + span_err(span, "invalid applicability").emit(); + Applicability::Unspecified + } + }; + self.applicability.set_once((quote! { #value }, span)); + } + _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| { + diag.help("only `code`, `slug` and `applicability` are valid nested attributes") + }), + } + } + _ => throw_invalid_nested_attr!(attr, &nested_attr), + } + } + + let Ok(kind) = SubdiagnosticKind::from_str(name) else { + throw_invalid_attr!(attr, &meta) + }; + + kind + } + _ => throw_invalid_attr!(attr, &meta), + }; + + if matches!( + kind, + SubdiagnosticKind::Label | SubdiagnosticKind::Help | SubdiagnosticKind::Note + ) && self.code.is_some() + { + throw_span_err!( + span, + &format!("`code` is not a valid nested attribute of a `{}` attribute", name) + ); + } + + if self.slug.is_none() { + throw_span_err!( + span, + &format!("`slug` must be set in a `#[{}(...)]` attribute", name) + ); + } + + self.kind.set_once((kind, span)); + } + + Ok(()) + } + + fn generate_field_code( + &mut self, + binding: &BindingInfo<'_>, + is_suggestion: bool, + ) -> Result<TokenStream, SessionDiagnosticDeriveError> { + let ast = binding.ast(); + + let option_ty = option_inner_ty(&ast.ty); + let info = FieldInfo { + vis: &ast.vis, + binding: binding, + ty: option_ty.unwrap_or(&ast.ty), + span: &ast.span(), + }; + + for attr in &ast.attrs { + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + let span = attr.span().unwrap(); + + let meta = attr.parse_meta()?; + match meta { + Meta::Path(_) => match name { + "primary_span" => { + report_error_if_not_applied_to_span(attr, &info)?; + self.span_field.set_once((binding.binding.clone(), span)); + return Ok(quote! {}); + } + "applicability" if is_suggestion => { + report_error_if_not_applied_to_applicability(attr, &info)?; + let binding = binding.binding.clone(); + self.applicability.set_once((quote! { #binding }, span)); + return Ok(quote! {}); + } + "applicability" => { + span_err(span, "`#[applicability]` is only valid on suggestions").emit(); + return Ok(quote! {}); + } + "skip_arg" => { + return Ok(quote! {}); + } + _ => throw_invalid_attr!(attr, &meta, |diag| { + diag.help("only `primary_span`, `applicability` and `skip_arg` are valid field attributes") + }), + }, + _ => throw_invalid_attr!(attr, &meta), + } + } + + let ident = ast.ident.as_ref().unwrap(); + + let diag = &self.diag; + let generated = quote! { + #diag.set_arg( + stringify!(#ident), + #binding.into_diagnostic_arg() + ); + }; + + if option_ty.is_none() { + Ok(quote! { #generated }) + } else { + Ok(quote! { + if let Some(#binding) = #binding { + #generated + } + }) + } + } + + fn into_tokens(&mut self) -> Result<TokenStream, SessionDiagnosticDeriveError> { + self.identify_kind()?; + let Some(kind) = self.kind.map(|(kind, _)| kind) else { + throw_span_err!( + self.variant.ast().ident.span().unwrap(), + "subdiagnostic kind not specified" + ); + }; + + let is_suggestion = matches!(kind, SubdiagnosticKind::Suggestion(_)); + + let mut args = TokenStream::new(); + for binding in self.variant.bindings() { + let arg = self + .generate_field_code(binding, is_suggestion) + .unwrap_or_else(|v| v.to_compile_error()); + args.extend(arg); + } + + // Missing slug errors will already have been reported. + let slug = self.slug.as_ref().map(|(slug, _)| &**slug).unwrap_or("missing-slug"); + let code = match self.code.as_ref() { + Some((code, _)) => Some(quote! { #code }), + None if is_suggestion => { + span_err(self.span, "suggestion without `code = \"...\"`").emit(); + Some(quote! { /* macro error */ "..." }) + } + None => None, + }; + + let span_field = self.span_field.as_ref().map(|(span, _)| span); + let applicability = match self.applicability.clone() { + Some((applicability, _)) => Some(applicability), + None if is_suggestion => { + span_err(self.span, "suggestion without `applicability`").emit(); + Some(quote! { rustc_errors::Applicability::Unspecified }) + } + None => None, + }; + + let diag = &self.diag; + let name = format_ident!("{}{}", if span_field.is_some() { "span_" } else { "" }, kind); + let message = quote! { rustc_errors::DiagnosticMessage::fluent(#slug) }; + let call = if matches!(kind, SubdiagnosticKind::Suggestion(..)) { + if let Some(span) = span_field { + quote! { #diag.#name(#span, #message, #code, #applicability); } + } else { + span_err(self.span, "suggestion without `#[primary_span]` field").emit(); + quote! { unreachable!(); } + } + } else if matches!(kind, SubdiagnosticKind::Label) { + if let Some(span) = span_field { + quote! { #diag.#name(#span, #message); } + } else { + span_err(self.span, "label without `#[primary_span]` field").emit(); + quote! { unreachable!(); } + } + } else { + if let Some(span) = span_field { + quote! { #diag.#name(#span, #message); } + } else { + quote! { #diag.#name(#message); } + } + }; + + Ok(quote! { + #call + #args + }) + } +} diff --git a/compiler/rustc_macros/src/diagnostics/utils.rs b/compiler/rustc_macros/src/diagnostics/utils.rs new file mode 100644 index 00000000000..1f36af0a20b --- /dev/null +++ b/compiler/rustc_macros/src/diagnostics/utils.rs @@ -0,0 +1,267 @@ +use crate::diagnostics::error::{span_err, throw_span_err, SessionDiagnosticDeriveError}; +use proc_macro::Span; +use proc_macro2::TokenStream; +use quote::{format_ident, quote}; +use std::collections::BTreeSet; +use std::str::FromStr; +use syn::{spanned::Spanned, Attribute, Meta, Type, Visibility}; +use synstructure::BindingInfo; + +/// Checks whether the type name of `ty` matches `name`. +/// +/// Given some struct at `a::b::c::Foo`, this will return true for `c::Foo`, `b::c::Foo`, or +/// `a::b::c::Foo`. This reasonably allows qualified names to be used in the macro. +pub(crate) fn type_matches_path(ty: &Type, name: &[&str]) -> bool { + if let Type::Path(ty) = ty { + ty.path + .segments + .iter() + .map(|s| s.ident.to_string()) + .rev() + .zip(name.iter().rev()) + .all(|(x, y)| &x.as_str() == y) + } else { + false + } +} + +/// Reports an error if the field's type is not `Applicability`. +fn report_error_if_not_applied_to_ty( + attr: &Attribute, + info: &FieldInfo<'_>, + path: &[&str], + ty_name: &str, +) -> Result<(), SessionDiagnosticDeriveError> { + if !type_matches_path(&info.ty, path) { + let name = attr.path.segments.last().unwrap().ident.to_string(); + let name = name.as_str(); + let meta = attr.parse_meta()?; + + throw_span_err!( + attr.span().unwrap(), + &format!( + "the `#[{}{}]` attribute can only be applied to fields of type `{}`", + name, + match meta { + Meta::Path(_) => "", + Meta::NameValue(_) => " = ...", + Meta::List(_) => "(...)", + }, + ty_name + ) + ); + } + + Ok(()) +} + +/// Reports an error if the field's type is not `Applicability`. +pub(crate) fn report_error_if_not_applied_to_applicability( + attr: &Attribute, + info: &FieldInfo<'_>, +) -> Result<(), SessionDiagnosticDeriveError> { + report_error_if_not_applied_to_ty( + attr, + info, + &["rustc_errors", "Applicability"], + "Applicability", + ) +} + +/// Reports an error if the field's type is not `Span`. +pub(crate) fn report_error_if_not_applied_to_span( + attr: &Attribute, + info: &FieldInfo<'_>, +) -> Result<(), SessionDiagnosticDeriveError> { + report_error_if_not_applied_to_ty(attr, info, &["rustc_span", "Span"], "Span") +} + +/// If `ty` is an Option, returns `Some(inner type)`, otherwise returns `None`. +pub(crate) fn option_inner_ty(ty: &Type) -> Option<&Type> { + if type_matches_path(ty, &["std", "option", "Option"]) { + if let Type::Path(ty_path) = ty { + let path = &ty_path.path; + let ty = path.segments.iter().last().unwrap(); + if let syn::PathArguments::AngleBracketed(bracketed) = &ty.arguments { + if bracketed.args.len() == 1 { + if let syn::GenericArgument::Type(ty) = &bracketed.args[0] { + return Some(ty); + } + } + } + } + } + None +} + +/// Field information passed to the builder. Deliberately omits attrs to discourage the +/// `generate_*` methods from walking the attributes themselves. +pub(crate) struct FieldInfo<'a> { + pub(crate) vis: &'a Visibility, + pub(crate) binding: &'a BindingInfo<'a>, + pub(crate) ty: &'a Type, + pub(crate) span: &'a proc_macro2::Span, +} + +/// Small helper trait for abstracting over `Option` fields that contain a value and a `Span` +/// for error reporting if they are set more than once. +pub(crate) trait SetOnce<T> { + fn set_once(&mut self, value: T); +} + +impl<T> SetOnce<(T, Span)> for Option<(T, Span)> { + fn set_once(&mut self, (value, span): (T, Span)) { + match self { + None => { + *self = Some((value, span)); + } + Some((_, prev_span)) => { + span_err(span, "specified multiple times") + .span_note(*prev_span, "previously specified here") + .emit(); + } + } + } +} + +pub(crate) trait HasFieldMap { + /// Returns the binding for the field with the given name, if it exists on the type. + fn get_field_binding(&self, field: &String) -> Option<&TokenStream>; + + /// In the strings in the attributes supplied to this macro, we want callers to be able to + /// reference fields in the format string. For example: + /// + /// ```ignore (not-usage-example) + /// /// Suggest `==` when users wrote `===`. + /// #[suggestion(slug = "parser-not-javascript-eq", code = "{lhs} == {rhs}")] + /// struct NotJavaScriptEq { + /// #[primary_span] + /// span: Span, + /// lhs: Ident, + /// rhs: Ident, + /// } + /// ``` + /// + /// We want to automatically pick up that `{lhs}` refers `self.lhs` and `{rhs}` refers to + /// `self.rhs`, then generate this call to `format!`: + /// + /// ```ignore (not-usage-example) + /// format!("{lhs} == {rhs}", lhs = self.lhs, rhs = self.rhs) + /// ``` + /// + /// This function builds the entire call to `format!`. + fn build_format(&self, input: &str, span: proc_macro2::Span) -> TokenStream { + // This set is used later to generate the final format string. To keep builds reproducible, + // the iteration order needs to be deterministic, hence why we use a `BTreeSet` here + // instead of a `HashSet`. + let mut referenced_fields: BTreeSet<String> = BTreeSet::new(); + + // At this point, we can start parsing the format string. + let mut it = input.chars().peekable(); + + // Once the start of a format string has been found, process the format string and spit out + // the referenced fields. Leaves `it` sitting on the closing brace of the format string, so + // the next call to `it.next()` retrieves the next character. + while let Some(c) = it.next() { + if c == '{' && *it.peek().unwrap_or(&'\0') != '{' { + let mut eat_argument = || -> Option<String> { + let mut result = String::new(); + // Format specifiers look like: + // + // format := '{' [ argument ] [ ':' format_spec ] '}' . + // + // Therefore, we only need to eat until ':' or '}' to find the argument. + while let Some(c) = it.next() { + result.push(c); + let next = *it.peek().unwrap_or(&'\0'); + if next == '}' { + break; + } else if next == ':' { + // Eat the ':' character. + assert_eq!(it.next().unwrap(), ':'); + break; + } + } + // Eat until (and including) the matching '}' + while it.next()? != '}' { + continue; + } + Some(result) + }; + + if let Some(referenced_field) = eat_argument() { + referenced_fields.insert(referenced_field); + } + } + } + + // At this point, `referenced_fields` contains a set of the unique fields that were + // referenced in the format string. Generate the corresponding "x = self.x" format + // string parameters: + let args = referenced_fields.into_iter().map(|field: String| { + let field_ident = format_ident!("{}", field); + let value = match self.get_field_binding(&field) { + Some(value) => value.clone(), + // This field doesn't exist. Emit a diagnostic. + None => { + span_err( + span.unwrap(), + &format!("`{}` doesn't refer to a field on this type", field), + ) + .emit(); + quote! { + "{#field}" + } + } + }; + quote! { + #field_ident = #value + } + }); + quote! { + format!(#input #(,#args)*) + } + } +} + +/// `Applicability` of a suggestion - mirrors `rustc_errors::Applicability` - and used to represent +/// the user's selection of applicability if specified in an attribute. +pub(crate) enum Applicability { + MachineApplicable, + MaybeIncorrect, + HasPlaceholders, + Unspecified, +} + +impl FromStr for Applicability { + type Err = (); + + fn from_str(s: &str) -> Result<Self, Self::Err> { + match s { + "machine-applicable" => Ok(Applicability::MachineApplicable), + "maybe-incorrect" => Ok(Applicability::MaybeIncorrect), + "has-placeholders" => Ok(Applicability::HasPlaceholders), + "unspecified" => Ok(Applicability::Unspecified), + _ => Err(()), + } + } +} + +impl quote::ToTokens for Applicability { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend(match self { + Applicability::MachineApplicable => { + quote! { rustc_errors::Applicability::MachineApplicable } + } + Applicability::MaybeIncorrect => { + quote! { rustc_errors::Applicability::MaybeIncorrect } + } + Applicability::HasPlaceholders => { + quote! { rustc_errors::Applicability::HasPlaceholders } + } + Applicability::Unspecified => { + quote! { rustc_errors::Applicability::Unspecified } + } + }); + } +} |