blob: b3bf9ad599acc10c412701c383f3006b50120402 [file] [log] [blame]
use super::{ObligationCauseCode, PredicateObligation};
use crate::infer::error_reporting::TypeErrCtxt;
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 as hir;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::SubstsRef;
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};
use std::iter;
use crate::errors::{
EmptyOnClauseInOnUnimplemented, InvalidOnClauseInOnUnimplemented, NoValueInOnUnimplemented,
};
use super::InferCtxtPrivExt;
pub trait TypeErrCtxtExt<'tcx> {
/*private*/
fn impl_similar_to(
&self,
trait_ref: ty::PolyTraitRef<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> Option<(DefId, SubstsRef<'tcx>)>;
/*private*/
fn describe_enclosure(&self, hir_id: hir::HirId) -> Option<&'static str>;
fn on_unimplemented_note(
&self,
trait_ref: ty::PolyTraitRef<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> OnUnimplementedNote;
}
/// The symbols which are always allowed in a format string
static ALLOWED_FORMAT_SYMBOLS: &[Symbol] = &[
kw::SelfUpper,
sym::ItemContext,
sym::from_method,
sym::from_desugaring,
sym::direct,
sym::cause,
sym::integral,
sym::integer_,
sym::float,
sym::_Self,
sym::crate_local,
];
impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
fn impl_similar_to(
&self,
trait_ref: ty::PolyTraitRef<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> Option<(DefId, SubstsRef<'tcx>)> {
let tcx = self.tcx;
let param_env = obligation.param_env;
let trait_ref = self.instantiate_binder_with_placeholders(trait_ref);
let trait_self_ty = trait_ref.self_ty();
let mut self_match_impls = vec![];
let mut fuzzy_match_impls = vec![];
self.tcx.for_each_relevant_impl(trait_ref.def_id, trait_self_ty, |def_id| {
let impl_substs = self.fresh_substs_for_item(obligation.cause.span, def_id);
let impl_trait_ref = tcx.impl_trait_ref(def_id).unwrap().subst(tcx, impl_substs);
let impl_self_ty = impl_trait_ref.self_ty();
if self.can_eq(param_env, trait_self_ty, impl_self_ty) {
self_match_impls.push((def_id, impl_substs));
if iter::zip(
trait_ref.substs.types().skip(1),
impl_trait_ref.substs.types().skip(1),
)
.all(|(u, v)| self.fuzzy_match_tys(u, v, false).is_some())
{
fuzzy_match_impls.push((def_id, impl_substs));
}
}
});
let impl_def_id_and_substs = if self_match_impls.len() == 1 {
self_match_impls[0]
} else if fuzzy_match_impls.len() == 1 {
fuzzy_match_impls[0]
} else {
return None;
};
tcx.has_attr(impl_def_id_and_substs.0, sym::rustc_on_unimplemented)
.then_some(impl_def_id_and_substs)
}
/// Used to set on_unimplemented's `ItemContext`
/// to be the enclosing (async) block/function/closure
fn describe_enclosure(&self, hir_id: hir::HirId) -> Option<&'static str> {
let hir = self.tcx.hir();
let node = hir.find(hir_id)?;
match &node {
hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, _, body_id), .. }) => {
self.describe_generator(*body_id).or_else(|| {
Some(match sig.header {
hir::FnHeader { asyncness: hir::IsAsync::Async, .. } => "an async function",
_ => "a function",
})
})
}
hir::Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body_id)),
..
}) => self.describe_generator(*body_id).or_else(|| Some("a trait method")),
hir::Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Fn(sig, body_id),
..
}) => self.describe_generator(*body_id).or_else(|| {
Some(match sig.header {
hir::FnHeader { asyncness: hir::IsAsync::Async, .. } => "an async method",
_ => "a method",
})
}),
hir::Node::Expr(hir::Expr {
kind: hir::ExprKind::Closure(hir::Closure { body, movability, .. }),
..
}) => self.describe_generator(*body).or_else(|| {
Some(if movability.is_some() { "an async closure" } else { "a closure" })
}),
hir::Node::Expr(hir::Expr { .. }) => {
let parent_hid = hir.parent_id(hir_id);
if parent_hid != hir_id { self.describe_enclosure(parent_hid) } else { None }
}
_ => None,
}
}
fn on_unimplemented_note(
&self,
trait_ref: ty::PolyTraitRef<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> OnUnimplementedNote {
let (def_id, substs) = self
.impl_similar_to(trait_ref, obligation)
.unwrap_or_else(|| (trait_ref.def_id(), trait_ref.skip_binder().substs));
let trait_ref = trait_ref.skip_binder();
let body_hir = self.tcx.hir().local_def_id_to_hir_id(obligation.cause.body_id);
let mut flags =
vec![(sym::ItemContext, self.describe_enclosure(body_hir).map(|s| s.to_owned()))];
match obligation.cause.code() {
ObligationCauseCode::BuiltinDerivedObligation(..)
| ObligationCauseCode::ImplDerivedObligation(..)
| ObligationCauseCode::DerivedObligation(..) => {}
_ => {
// this is a "direct", user-specified, rather than derived,
// obligation.
flags.push((sym::direct, None));
}
}
if let ObligationCauseCode::ItemObligation(item)
| ObligationCauseCode::BindingObligation(item, _)
| ObligationCauseCode::ExprItemObligation(item, ..)
| ObligationCauseCode::ExprBindingObligation(item, ..) = *obligation.cause.code()
{
// FIXME: maybe also have some way of handling methods
// from other traits? That would require name resolution,
// which we might want to be some sort of hygienic.
//
// Currently I'm leaving it for what I need for `try`.
if self.tcx.trait_of_item(item) == Some(trait_ref.def_id) {
let method = self.tcx.item_name(item);
flags.push((sym::from_method, None));
flags.push((sym::from_method, Some(method.to_string())));
}
}
if let Some(k) = obligation.cause.span.desugaring_kind() {
flags.push((sym::from_desugaring, None));
flags.push((sym::from_desugaring, Some(format!("{:?}", k))));
}
if let ObligationCauseCode::MainFunctionType = obligation.cause.code() {
flags.push((sym::cause, Some("MainFunctionType".to_string())));
}
// Add all types without trimmed paths.
ty::print::with_no_trimmed_paths!({
let generics = self.tcx.generics_of(def_id);
let self_ty = trait_ref.self_ty();
// This is also included through the generics list as `Self`,
// but the parser won't allow you to use it
flags.push((sym::_Self, Some(self_ty.to_string())));
if let Some(def) = self_ty.ty_adt_def() {
// We also want to be able to select self's original
// signature with no type arguments resolved
flags.push((
sym::_Self,
Some(self.tcx.type_of(def.did()).subst_identity().to_string()),
));
}
for param in generics.params.iter() {
let value = match param.kind {
GenericParamDefKind::Type { .. } | GenericParamDefKind::Const { .. } => {
substs[param.index as usize].to_string()
}
GenericParamDefKind::Lifetime => continue,
};
let name = param.name;
flags.push((name, Some(value)));
if let GenericParamDefKind::Type { .. } = param.kind {
let param_ty = substs[param.index as usize].expect_ty();
if let Some(def) = param_ty.ty_adt_def() {
// We also want to be able to select the parameter's
// original signature with no type arguments resolved
flags.push((
name,
Some(self.tcx.type_of(def.did()).subst_identity().to_string()),
));
}
}
}
if let Some(true) = self_ty.ty_adt_def().map(|def| def.did().is_local()) {
flags.push((sym::crate_local, None));
}
// Allow targeting all integers using `{integral}`, even if the exact type was resolved
if self_ty.is_integral() {
flags.push((sym::_Self, Some("{integral}".to_owned())));
}
if self_ty.is_array_slice() {
flags.push((sym::_Self, Some("&[]".to_owned())));
}
if self_ty.is_fn() {
let fn_sig = self_ty.fn_sig(self.tcx);
let shortname = match fn_sig.unsafety() {
hir::Unsafety::Normal => "fn",
hir::Unsafety::Unsafe => "unsafe fn",
};
flags.push((sym::_Self, Some(shortname.to_owned())));
}
// Slices give us `[]`, `[{ty}]`
if let ty::Slice(aty) = self_ty.kind() {
flags.push((sym::_Self, Some("[]".to_string())));
if let Some(def) = aty.ty_adt_def() {
// We also want to be able to select the slice's type's original
// signature with no type arguments resolved
flags.push((
sym::_Self,
Some(format!("[{}]", self.tcx.type_of(def.did()).subst_identity())),
));
}
if aty.is_integral() {
flags.push((sym::_Self, Some("[{integral}]".to_string())));
}
}
// Arrays give us `[]`, `[{ty}; _]` and `[{ty}; N]`
if let ty::Array(aty, len) = self_ty.kind() {
flags.push((sym::_Self, Some("[]".to_string())));
let len = len.kind().try_to_value().and_then(|v| v.try_to_target_usize(self.tcx));
flags.push((sym::_Self, Some(format!("[{}; _]", aty))));
if let Some(n) = len {
flags.push((sym::_Self, Some(format!("[{}; {}]", aty, n))));
}
if let Some(def) = aty.ty_adt_def() {
// We also want to be able to select the array's type's original
// signature with no type arguments resolved
let def_ty = self.tcx.type_of(def.did()).subst_identity();
flags.push((sym::_Self, Some(format!("[{def_ty}; _]"))));
if let Some(n) = len {
flags.push((sym::_Self, Some(format!("[{def_ty}; {n}]"))));
}
}
if aty.is_integral() {
flags.push((sym::_Self, Some("[{integral}; _]".to_string())));
if let Some(n) = len {
flags.push((sym::_Self, Some(format!("[{{integral}}; {n}]"))));
}
}
}
if let ty::Dynamic(traits, _, _) = self_ty.kind() {
for t in traits.iter() {
if let ty::ExistentialPredicate::Trait(trait_ref) = t.skip_binder() {
flags.push((sym::_Self, Some(self.tcx.def_path_str(trait_ref.def_id))))
}
}
}
});
if let Ok(Some(command)) = OnUnimplementedDirective::of_item(self.tcx, def_id) {
command.evaluate(self.tcx, trait_ref, &flags)
} else {
OnUnimplementedNote::default()
}
}
}
#[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 parent_label: Option<OnUnimplementedFormatString>,
pub append_const_msg: Option<Option<Symbol>>,
}
/// For the `#[rustc_on_unimplemented]` attribute
#[derive(Default)]
pub struct OnUnimplementedNote {
pub message: Option<String>,
pub label: Option<String>,
pub note: Option<String>,
pub parent_label: 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>>,
}
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(|| tcx.sess.emit_err(EmptyOnClauseInOnUnimplemented { span }))?
.meta_item()
.ok_or_else(|| tcx.sess.emit_err(InvalidOnClauseInOnUnimplemented { span }))?;
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 parent_label = 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::parent_label) && parent_label.is_none() {
if let Some(parent_label_) = item.value_str() {
parent_label = parse_value(parent_label_)?;
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
tcx.sess.emit_err(NoValueInOnUnimplemented { span: item.span() });
}
if let Some(reported) = errored {
Err(reported)
} else {
Ok(OnUnimplementedDirective {
condition,
subcommands,
message,
label,
note,
parent_label,
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,
parent_label: 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 parent_label = 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.clone().map(|v| (*k, v))).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 parent_label_) = command.parent_label {
parent_label = Some(parent_label_.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)),
parent_label: parent_label.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) {
// `{ThisTraitsName}` is allowed
s if s == trait_name => (),
s if ALLOWED_FORMAT_SYMBOLS.contains(&s) => (),
// So is `{A}` if A is a type parameter
s if generics.params.iter().any(|param| param.name == s) => (),
s => {
result = Err(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());
}
}
}
// `{: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()
}
}