diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/on_unimplemented.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/on_unimplemented.rs | 425 |
1 files changed, 425 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/on_unimplemented.rs new file mode 100644 index 000000000..9227bbf01 --- /dev/null +++ b/compiler/rustc_trait_selection/src/traits/on_unimplemented.rs @@ -0,0 +1,425 @@ +use rustc_ast::{MetaItem, NestedMetaItem}; +use rustc_attr as attr; +use rustc_data_structures::fx::FxHashMap; +use rustc_errors::{struct_span_err, ErrorGuaranteed}; +use rustc_hir::def_id::DefId; +use rustc_middle::ty::{self, GenericParamDefKind, TyCtxt}; +use rustc_parse_format::{ParseMode, Parser, Piece, Position}; +use rustc_span::symbol::{kw, sym, Symbol}; +use rustc_span::{Span, DUMMY_SP}; + +#[derive(Clone, Debug)] +pub struct OnUnimplementedFormatString(Symbol); + +#[derive(Debug)] +pub struct OnUnimplementedDirective { + pub condition: Option<MetaItem>, + pub subcommands: Vec<OnUnimplementedDirective>, + pub message: Option<OnUnimplementedFormatString>, + pub label: Option<OnUnimplementedFormatString>, + pub note: Option<OnUnimplementedFormatString>, + pub enclosing_scope: Option<OnUnimplementedFormatString>, + pub append_const_msg: Option<Option<Symbol>>, +} + +#[derive(Default)] +pub struct OnUnimplementedNote { + pub message: Option<String>, + pub label: Option<String>, + pub note: Option<String>, + pub enclosing_scope: Option<String>, + /// Append a message for `~const Trait` errors. `None` means not requested and + /// should fallback to a generic message, `Some(None)` suggests using the default + /// appended message, `Some(Some(s))` suggests use the `s` message instead of the + /// default one.. + pub append_const_msg: Option<Option<Symbol>>, +} + +fn parse_error( + tcx: TyCtxt<'_>, + span: Span, + message: &str, + label: &str, + note: Option<&str>, +) -> ErrorGuaranteed { + let mut diag = struct_span_err!(tcx.sess, span, E0232, "{}", message); + diag.span_label(span, label); + if let Some(note) = note { + diag.note(note); + } + diag.emit() +} + +impl<'tcx> OnUnimplementedDirective { + fn parse( + tcx: TyCtxt<'tcx>, + item_def_id: DefId, + items: &[NestedMetaItem], + span: Span, + is_root: bool, + ) -> Result<Self, ErrorGuaranteed> { + let mut errored = None; + let mut item_iter = items.iter(); + + let parse_value = |value_str| { + OnUnimplementedFormatString::try_parse(tcx, item_def_id, value_str, span).map(Some) + }; + + let condition = if is_root { + None + } else { + let cond = item_iter + .next() + .ok_or_else(|| { + parse_error( + tcx, + span, + "empty `on`-clause in `#[rustc_on_unimplemented]`", + "empty on-clause here", + None, + ) + })? + .meta_item() + .ok_or_else(|| { + parse_error( + tcx, + span, + "invalid `on`-clause in `#[rustc_on_unimplemented]`", + "invalid on-clause here", + None, + ) + })?; + attr::eval_condition(cond, &tcx.sess.parse_sess, Some(tcx.features()), &mut |cfg| { + if let Some(value) = cfg.value && let Err(guar) = parse_value(value) { + errored = Some(guar); + } + true + }); + Some(cond.clone()) + }; + + let mut message = None; + let mut label = None; + let mut note = None; + let mut enclosing_scope = None; + let mut subcommands = vec![]; + let mut append_const_msg = None; + + for item in item_iter { + if item.has_name(sym::message) && message.is_none() { + if let Some(message_) = item.value_str() { + message = parse_value(message_)?; + continue; + } + } else if item.has_name(sym::label) && label.is_none() { + if let Some(label_) = item.value_str() { + label = parse_value(label_)?; + continue; + } + } else if item.has_name(sym::note) && note.is_none() { + if let Some(note_) = item.value_str() { + note = parse_value(note_)?; + continue; + } + } else if item.has_name(sym::enclosing_scope) && enclosing_scope.is_none() { + if let Some(enclosing_scope_) = item.value_str() { + enclosing_scope = parse_value(enclosing_scope_)?; + continue; + } + } else if item.has_name(sym::on) + && is_root + && message.is_none() + && label.is_none() + && note.is_none() + { + if let Some(items) = item.meta_item_list() { + match Self::parse(tcx, item_def_id, &items, item.span(), false) { + Ok(subcommand) => subcommands.push(subcommand), + Err(reported) => errored = Some(reported), + }; + continue; + } + } else if item.has_name(sym::append_const_msg) && append_const_msg.is_none() { + if let Some(msg) = item.value_str() { + append_const_msg = Some(Some(msg)); + continue; + } else if item.is_word() { + append_const_msg = Some(None); + continue; + } + } + + // nothing found + parse_error( + tcx, + item.span(), + "this attribute must have a valid value", + "expected value here", + Some(r#"eg `#[rustc_on_unimplemented(message="foo")]`"#), + ); + } + + if let Some(reported) = errored { + Err(reported) + } else { + Ok(OnUnimplementedDirective { + condition, + subcommands, + message, + label, + note, + enclosing_scope, + append_const_msg, + }) + } + } + + pub fn of_item(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> Result<Option<Self>, ErrorGuaranteed> { + let Some(attr) = tcx.get_attr(item_def_id, sym::rustc_on_unimplemented) else { + return Ok(None); + }; + + let result = if let Some(items) = attr.meta_item_list() { + Self::parse(tcx, item_def_id, &items, attr.span, true).map(Some) + } else if let Some(value) = attr.value_str() { + Ok(Some(OnUnimplementedDirective { + condition: None, + message: None, + subcommands: vec![], + label: Some(OnUnimplementedFormatString::try_parse( + tcx, + item_def_id, + value, + attr.span, + )?), + note: None, + enclosing_scope: None, + append_const_msg: None, + })) + } else { + let reported = + tcx.sess.delay_span_bug(DUMMY_SP, "of_item: neither meta_item_list nor value_str"); + return Err(reported); + }; + debug!("of_item({:?}) = {:?}", item_def_id, result); + result + } + + pub fn evaluate( + &self, + tcx: TyCtxt<'tcx>, + trait_ref: ty::TraitRef<'tcx>, + options: &[(Symbol, Option<String>)], + ) -> OnUnimplementedNote { + let mut message = None; + let mut label = None; + let mut note = None; + let mut enclosing_scope = None; + let mut append_const_msg = None; + info!("evaluate({:?}, trait_ref={:?}, options={:?})", self, trait_ref, options); + + let options_map: FxHashMap<Symbol, String> = + options.iter().filter_map(|(k, v)| v.as_ref().map(|v| (*k, v.to_owned()))).collect(); + + for command in self.subcommands.iter().chain(Some(self)).rev() { + if let Some(ref condition) = command.condition && !attr::eval_condition( + condition, + &tcx.sess.parse_sess, + Some(tcx.features()), + &mut |cfg| { + let value = cfg.value.map(|v| { + OnUnimplementedFormatString(v).format(tcx, trait_ref, &options_map) + }); + + options.contains(&(cfg.name, value)) + }, + ) { + debug!("evaluate: skipping {:?} due to condition", command); + continue; + } + debug!("evaluate: {:?} succeeded", command); + if let Some(ref message_) = command.message { + message = Some(message_.clone()); + } + + if let Some(ref label_) = command.label { + label = Some(label_.clone()); + } + + if let Some(ref note_) = command.note { + note = Some(note_.clone()); + } + + if let Some(ref enclosing_scope_) = command.enclosing_scope { + enclosing_scope = Some(enclosing_scope_.clone()); + } + + append_const_msg = command.append_const_msg; + } + + OnUnimplementedNote { + label: label.map(|l| l.format(tcx, trait_ref, &options_map)), + message: message.map(|m| m.format(tcx, trait_ref, &options_map)), + note: note.map(|n| n.format(tcx, trait_ref, &options_map)), + enclosing_scope: enclosing_scope.map(|e_s| e_s.format(tcx, trait_ref, &options_map)), + append_const_msg, + } + } +} + +impl<'tcx> OnUnimplementedFormatString { + fn try_parse( + tcx: TyCtxt<'tcx>, + item_def_id: DefId, + from: Symbol, + err_sp: Span, + ) -> Result<Self, ErrorGuaranteed> { + let result = OnUnimplementedFormatString(from); + result.verify(tcx, item_def_id, err_sp)?; + Ok(result) + } + + fn verify( + &self, + tcx: TyCtxt<'tcx>, + item_def_id: DefId, + span: Span, + ) -> Result<(), ErrorGuaranteed> { + let trait_def_id = if tcx.is_trait(item_def_id) { + item_def_id + } else { + tcx.trait_id_of_impl(item_def_id) + .expect("expected `on_unimplemented` to correspond to a trait") + }; + let trait_name = tcx.item_name(trait_def_id); + let generics = tcx.generics_of(item_def_id); + let s = self.0.as_str(); + let parser = Parser::new(s, None, None, false, ParseMode::Format); + let mut result = Ok(()); + for token in parser { + match token { + Piece::String(_) => (), // Normal string, no need to check it + Piece::NextArgument(a) => match a.position { + Position::ArgumentNamed(s) => { + match Symbol::intern(s) { + // `{Self}` is allowed + kw::SelfUpper => (), + // `{ThisTraitsName}` is allowed + s if s == trait_name => (), + // `{from_method}` is allowed + sym::from_method => (), + // `{from_desugaring}` is allowed + sym::from_desugaring => (), + // `{ItemContext}` is allowed + sym::ItemContext => (), + // `{integral}` and `{integer}` and `{float}` are allowed + sym::integral | sym::integer_ | sym::float => (), + // So is `{A}` if A is a type parameter + s => match generics.params.iter().find(|param| param.name == s) { + Some(_) => (), + None => { + let reported = struct_span_err!( + tcx.sess, + span, + E0230, + "there is no parameter `{}` on {}", + s, + if trait_def_id == item_def_id { + format!("trait `{}`", trait_name) + } else { + "impl".to_string() + } + ) + .emit(); + result = Err(reported); + } + }, + } + } + // `{:1}` and `{}` are not to be used + Position::ArgumentIs(..) | Position::ArgumentImplicitlyIs(_) => { + let reported = struct_span_err!( + tcx.sess, + span, + E0231, + "only named substitution parameters are allowed" + ) + .emit(); + result = Err(reported); + } + }, + } + } + + result + } + + pub fn format( + &self, + tcx: TyCtxt<'tcx>, + trait_ref: ty::TraitRef<'tcx>, + options: &FxHashMap<Symbol, String>, + ) -> String { + let name = tcx.item_name(trait_ref.def_id); + let trait_str = tcx.def_path_str(trait_ref.def_id); + let generics = tcx.generics_of(trait_ref.def_id); + let generic_map = generics + .params + .iter() + .filter_map(|param| { + let value = match param.kind { + GenericParamDefKind::Type { .. } | GenericParamDefKind::Const { .. } => { + trait_ref.substs[param.index as usize].to_string() + } + GenericParamDefKind::Lifetime => return None, + }; + let name = param.name; + Some((name, value)) + }) + .collect::<FxHashMap<Symbol, String>>(); + let empty_string = String::new(); + + let s = self.0.as_str(); + let parser = Parser::new(s, None, None, false, ParseMode::Format); + let item_context = (options.get(&sym::ItemContext)).unwrap_or(&empty_string); + parser + .map(|p| match p { + Piece::String(s) => s, + Piece::NextArgument(a) => match a.position { + Position::ArgumentNamed(s) => { + let s = Symbol::intern(s); + match generic_map.get(&s) { + Some(val) => val, + None if s == name => &trait_str, + None => { + if let Some(val) = options.get(&s) { + val + } else if s == sym::from_desugaring || s == sym::from_method { + // don't break messages using these two arguments incorrectly + &empty_string + } else if s == sym::ItemContext { + &item_context + } else if s == sym::integral { + "{integral}" + } else if s == sym::integer_ { + "{integer}" + } else if s == sym::float { + "{float}" + } else { + bug!( + "broken on_unimplemented {:?} for {:?}: \ + no argument matching {:?}", + self.0, + trait_ref, + s + ) + } + } + } + } + _ => bug!("broken on_unimplemented {:?} - bad format arg", self.0), + }, + }) + .collect() + } +} |