+++ /dev/null
-use super::IsMethodCall;
-use crate::astconv::{
- AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
- GenericArgCountResult, GenericArgPosition,
-};
-use crate::errors::AssocTypeBindingNotAllowed;
-use crate::structured_errors::{GenericArgsInfo, StructuredDiagnostic, WrongNumberOfGenericArgs};
-use rustc_ast::ast::ParamKindOrd;
-use rustc_errors::{struct_span_err, Applicability, Diagnostic, MultiSpan};
-use rustc_hir as hir;
-use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id::DefId;
-use rustc_hir::GenericArg;
-use rustc_infer::infer::TyCtxtInferExt;
-use rustc_middle::ty::{
- self, subst, subst::SubstsRef, GenericParamDef, GenericParamDefKind, IsSuggestable, Ty, TyCtxt,
-};
-use rustc_session::lint::builtin::LATE_BOUND_LIFETIME_ARGUMENTS;
-use rustc_span::{symbol::kw, Span};
-use smallvec::SmallVec;
-
-impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
- /// Report an error that a generic argument did not match the generic parameter that was
- /// expected.
- fn generic_arg_mismatch_err(
- tcx: TyCtxt<'_>,
- arg: &GenericArg<'_>,
- param: &GenericParamDef,
- possible_ordering_error: bool,
- help: Option<&str>,
- ) {
- let sess = tcx.sess;
- let mut err = struct_span_err!(
- sess,
- arg.span(),
- E0747,
- "{} provided when a {} was expected",
- arg.descr(),
- param.kind.descr(),
- );
-
- if let GenericParamDefKind::Const { .. } = param.kind {
- if matches!(arg, GenericArg::Type(hir::Ty { kind: hir::TyKind::Infer, .. })) {
- err.help("const arguments cannot yet be inferred with `_`");
- if sess.is_nightly_build() {
- err.help(
- "add `#![feature(generic_arg_infer)]` to the crate attributes to enable",
- );
- }
- }
- }
-
- let add_braces_suggestion = |arg: &GenericArg<'_>, err: &mut Diagnostic| {
- let suggestions = vec![
- (arg.span().shrink_to_lo(), String::from("{ ")),
- (arg.span().shrink_to_hi(), String::from(" }")),
- ];
- err.multipart_suggestion(
- "if this generic argument was intended as a const parameter, \
- surround it with braces",
- suggestions,
- Applicability::MaybeIncorrect,
- );
- };
-
- // Specific suggestion set for diagnostics
- match (arg, ¶m.kind) {
- (
- GenericArg::Type(hir::Ty {
- kind: hir::TyKind::Path(rustc_hir::QPath::Resolved(_, path)),
- ..
- }),
- GenericParamDefKind::Const { .. },
- ) => match path.res {
- Res::Err => {
- add_braces_suggestion(arg, &mut err);
- err.set_primary_message(
- "unresolved item provided when a constant was expected",
- )
- .emit();
- return;
- }
- Res::Def(DefKind::TyParam, src_def_id) => {
- if let Some(param_local_id) = param.def_id.as_local() {
- let param_name = tcx.hir().ty_param_name(param_local_id);
- let param_type = tcx.infer_ctxt().enter(|infcx| {
- infcx.resolve_numeric_literals_with_default(tcx.type_of(param.def_id))
- });
- if param_type.is_suggestable(tcx, false) {
- err.span_suggestion(
- tcx.def_span(src_def_id),
- "consider changing this type parameter to be a `const` generic",
- format!("const {}: {}", param_name, param_type),
- Applicability::MaybeIncorrect,
- );
- };
- }
- }
- _ => add_braces_suggestion(arg, &mut err),
- },
- (
- GenericArg::Type(hir::Ty { kind: hir::TyKind::Path(_), .. }),
- GenericParamDefKind::Const { .. },
- ) => add_braces_suggestion(arg, &mut err),
- (
- GenericArg::Type(hir::Ty { kind: hir::TyKind::Array(_, len), .. }),
- GenericParamDefKind::Const { .. },
- ) if tcx.type_of(param.def_id) == tcx.types.usize => {
- let snippet = sess.source_map().span_to_snippet(tcx.hir().span(len.hir_id()));
- if let Ok(snippet) = snippet {
- err.span_suggestion(
- arg.span(),
- "array type provided where a `usize` was expected, try",
- format!("{{ {} }}", snippet),
- Applicability::MaybeIncorrect,
- );
- }
- }
- (GenericArg::Const(cnst), GenericParamDefKind::Type { .. }) => {
- let body = tcx.hir().body(cnst.value.body);
- if let rustc_hir::ExprKind::Path(rustc_hir::QPath::Resolved(_, path)) =
- body.value.kind
- {
- if let Res::Def(DefKind::Fn { .. }, id) = path.res {
- err.help(&format!(
- "`{}` is a function item, not a type",
- tcx.item_name(id)
- ));
- err.help("function item types cannot be named directly");
- }
- }
- }
- _ => {}
- }
-
- let kind_ord = param.kind.to_ord();
- let arg_ord = arg.to_ord();
-
- // This note is only true when generic parameters are strictly ordered by their kind.
- if possible_ordering_error && kind_ord.cmp(&arg_ord) != core::cmp::Ordering::Equal {
- let (first, last) = if kind_ord < arg_ord {
- (param.kind.descr(), arg.descr())
- } else {
- (arg.descr(), param.kind.descr())
- };
- err.note(&format!("{} arguments must be provided before {} arguments", first, last));
- if let Some(help) = help {
- err.help(help);
- }
- }
-
- err.emit();
- }
-
- /// Creates the relevant generic argument substitutions
- /// corresponding to a set of generic parameters. This is a
- /// rather complex function. Let us try to explain the role
- /// of each of its parameters:
- ///
- /// To start, we are given the `def_id` of the thing we are
- /// creating the substitutions for, and a partial set of
- /// substitutions `parent_substs`. In general, the substitutions
- /// for an item begin with substitutions for all the "parents" of
- /// that item -- e.g., for a method it might include the
- /// parameters from the impl.
- ///
- /// Therefore, the method begins by walking down these parents,
- /// starting with the outermost parent and proceed inwards until
- /// it reaches `def_id`. For each parent `P`, it will check `parent_substs`
- /// first to see if the parent's substitutions are listed in there. If so,
- /// we can append those and move on. Otherwise, it invokes the
- /// three callback functions:
- ///
- /// - `args_for_def_id`: given the `DefId` `P`, supplies back the
- /// generic arguments that were given to that parent from within
- /// the path; so e.g., if you have `<T as Foo>::Bar`, the `DefId`
- /// might refer to the trait `Foo`, and the arguments might be
- /// `[T]`. The boolean value indicates whether to infer values
- /// for arguments whose values were not explicitly provided.
- /// - `provided_kind`: given the generic parameter and the value from `args_for_def_id`,
- /// instantiate a `GenericArg`.
- /// - `inferred_kind`: if no parameter was provided, and inference is enabled, then
- /// creates a suitable inference variable.
- pub fn create_substs_for_generic_args<'a>(
- tcx: TyCtxt<'tcx>,
- def_id: DefId,
- parent_substs: &[subst::GenericArg<'tcx>],
- has_self: bool,
- self_ty: Option<Ty<'tcx>>,
- arg_count: &GenericArgCountResult,
- ctx: &mut impl CreateSubstsForGenericArgsCtxt<'a, 'tcx>,
- ) -> SubstsRef<'tcx> {
- // Collect the segments of the path; we need to substitute arguments
- // for parameters throughout the entire path (wherever there are
- // generic parameters).
- let mut parent_defs = tcx.generics_of(def_id);
- let count = parent_defs.count();
- let mut stack = vec![(def_id, parent_defs)];
- while let Some(def_id) = parent_defs.parent {
- parent_defs = tcx.generics_of(def_id);
- stack.push((def_id, parent_defs));
- }
-
- // We manually build up the substitution, rather than using convenience
- // methods in `subst.rs`, so that we can iterate over the arguments and
- // parameters in lock-step linearly, instead of trying to match each pair.
- let mut substs: SmallVec<[subst::GenericArg<'tcx>; 8]> = SmallVec::with_capacity(count);
- // Iterate over each segment of the path.
- while let Some((def_id, defs)) = stack.pop() {
- let mut params = defs.params.iter().peekable();
-
- // If we have already computed substitutions for parents, we can use those directly.
- while let Some(¶m) = params.peek() {
- if let Some(&kind) = parent_substs.get(param.index as usize) {
- substs.push(kind);
- params.next();
- } else {
- break;
- }
- }
-
- // `Self` is handled first, unless it's been handled in `parent_substs`.
- if has_self {
- if let Some(¶m) = params.peek() {
- if param.index == 0 {
- if let GenericParamDefKind::Type { .. } = param.kind {
- substs.push(
- self_ty
- .map(|ty| ty.into())
- .unwrap_or_else(|| ctx.inferred_kind(None, param, true)),
- );
- params.next();
- }
- }
- }
- }
-
- // Check whether this segment takes generic arguments and the user has provided any.
- let (generic_args, infer_args) = ctx.args_for_def_id(def_id);
-
- let args_iter = generic_args.iter().flat_map(|generic_args| generic_args.args.iter());
- let mut args = args_iter.clone().peekable();
-
- // If we encounter a type or const when we expect a lifetime, we infer the lifetimes.
- // If we later encounter a lifetime, we know that the arguments were provided in the
- // wrong order. `force_infer_lt` records the type or const that forced lifetimes to be
- // inferred, so we can use it for diagnostics later.
- let mut force_infer_lt = None;
-
- loop {
- // We're going to iterate through the generic arguments that the user
- // provided, matching them with the generic parameters we expect.
- // Mismatches can occur as a result of elided lifetimes, or for malformed
- // input. We try to handle both sensibly.
- match (args.peek(), params.peek()) {
- (Some(&arg), Some(¶m)) => {
- match (arg, ¶m.kind, arg_count.explicit_late_bound) {
- (GenericArg::Lifetime(_), GenericParamDefKind::Lifetime, _)
- | (
- GenericArg::Type(_) | GenericArg::Infer(_),
- GenericParamDefKind::Type { .. },
- _,
- )
- | (
- GenericArg::Const(_) | GenericArg::Infer(_),
- GenericParamDefKind::Const { .. },
- _,
- ) => {
- substs.push(ctx.provided_kind(param, arg));
- args.next();
- params.next();
- }
- (
- GenericArg::Infer(_) | GenericArg::Type(_) | GenericArg::Const(_),
- GenericParamDefKind::Lifetime,
- _,
- ) => {
- // We expected a lifetime argument, but got a type or const
- // argument. That means we're inferring the lifetimes.
- substs.push(ctx.inferred_kind(None, param, infer_args));
- force_infer_lt = Some((arg, param));
- params.next();
- }
- (GenericArg::Lifetime(_), _, ExplicitLateBound::Yes) => {
- // We've come across a lifetime when we expected something else in
- // the presence of explicit late bounds. This is most likely
- // due to the presence of the explicit bound so we're just going to
- // ignore it.
- args.next();
- }
- (_, _, _) => {
- // We expected one kind of parameter, but the user provided
- // another. This is an error. However, if we already know that
- // the arguments don't match up with the parameters, we won't issue
- // an additional error, as the user already knows what's wrong.
- if arg_count.correct.is_ok() {
- // We're going to iterate over the parameters to sort them out, and
- // show that order to the user as a possible order for the parameters
- let mut param_types_present = defs
- .params
- .iter()
- .map(|param| (param.kind.to_ord(), param.clone()))
- .collect::<Vec<(ParamKindOrd, GenericParamDef)>>();
- param_types_present.sort_by_key(|(ord, _)| *ord);
- let (mut param_types_present, ordered_params): (
- Vec<ParamKindOrd>,
- Vec<GenericParamDef>,
- ) = param_types_present.into_iter().unzip();
- param_types_present.dedup();
-
- Self::generic_arg_mismatch_err(
- tcx,
- arg,
- param,
- !args_iter.clone().is_sorted_by_key(|arg| arg.to_ord()),
- Some(&format!(
- "reorder the arguments: {}: `<{}>`",
- param_types_present
- .into_iter()
- .map(|ord| format!("{}s", ord))
- .collect::<Vec<String>>()
- .join(", then "),
- ordered_params
- .into_iter()
- .filter_map(|param| {
- if param.name == kw::SelfUpper {
- None
- } else {
- Some(param.name.to_string())
- }
- })
- .collect::<Vec<String>>()
- .join(", ")
- )),
- );
- }
-
- // We've reported the error, but we want to make sure that this
- // problem doesn't bubble down and create additional, irrelevant
- // errors. In this case, we're simply going to ignore the argument
- // and any following arguments. The rest of the parameters will be
- // inferred.
- while args.next().is_some() {}
- }
- }
- }
-
- (Some(&arg), None) => {
- // We should never be able to reach this point with well-formed input.
- // There are three situations in which we can encounter this issue.
- //
- // 1. The number of arguments is incorrect. In this case, an error
- // will already have been emitted, and we can ignore it.
- // 2. There are late-bound lifetime parameters present, yet the
- // lifetime arguments have also been explicitly specified by the
- // user.
- // 3. We've inferred some lifetimes, which have been provided later (i.e.
- // after a type or const). We want to throw an error in this case.
-
- if arg_count.correct.is_ok()
- && arg_count.explicit_late_bound == ExplicitLateBound::No
- {
- let kind = arg.descr();
- assert_eq!(kind, "lifetime");
- let (provided_arg, param) =
- force_infer_lt.expect("lifetimes ought to have been inferred");
- Self::generic_arg_mismatch_err(tcx, provided_arg, param, false, None);
- }
-
- break;
- }
-
- (None, Some(¶m)) => {
- // If there are fewer arguments than parameters, it means
- // we're inferring the remaining arguments.
- substs.push(ctx.inferred_kind(Some(&substs), param, infer_args));
- params.next();
- }
-
- (None, None) => break,
- }
- }
- }
-
- tcx.intern_substs(&substs)
- }
-
- /// Checks that the correct number of generic arguments have been provided.
- /// Used specifically for function calls.
- pub fn check_generic_arg_count_for_call(
- tcx: TyCtxt<'_>,
- span: Span,
- def_id: DefId,
- generics: &ty::Generics,
- seg: &hir::PathSegment<'_>,
- is_method_call: IsMethodCall,
- ) -> GenericArgCountResult {
- let empty_args = hir::GenericArgs::none();
- let gen_args = seg.args.unwrap_or(&empty_args);
- let gen_pos = if is_method_call == IsMethodCall::Yes {
- GenericArgPosition::MethodCall
- } else {
- GenericArgPosition::Value
- };
- let has_self = generics.parent.is_none() && generics.has_self;
-
- Self::check_generic_arg_count(
- tcx,
- span,
- def_id,
- seg,
- generics,
- gen_args,
- gen_pos,
- has_self,
- seg.infer_args,
- )
- }
-
- /// Checks that the correct number of generic arguments have been provided.
- /// This is used both for datatypes and function calls.
- #[instrument(skip(tcx, gen_pos), level = "debug")]
- pub(crate) fn check_generic_arg_count(
- tcx: TyCtxt<'_>,
- span: Span,
- def_id: DefId,
- seg: &hir::PathSegment<'_>,
- gen_params: &ty::Generics,
- gen_args: &hir::GenericArgs<'_>,
- gen_pos: GenericArgPosition,
- has_self: bool,
- infer_args: bool,
- ) -> GenericArgCountResult {
- let default_counts = gen_params.own_defaults();
- let param_counts = gen_params.own_counts();
-
- // Subtracting from param count to ensure type params synthesized from `impl Trait`
- // cannot be explicitly specified.
- let synth_type_param_count = gen_params
- .params
- .iter()
- .filter(|param| {
- matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: true, .. })
- })
- .count();
- let named_type_param_count =
- param_counts.types - has_self as usize - synth_type_param_count;
- let infer_lifetimes =
- (gen_pos != GenericArgPosition::Type || infer_args) && !gen_args.has_lifetime_params();
-
- if gen_pos != GenericArgPosition::Type && !gen_args.bindings.is_empty() {
- Self::prohibit_assoc_ty_binding(tcx, gen_args.bindings[0].span);
- }
-
- let explicit_late_bound =
- Self::prohibit_explicit_late_bound_lifetimes(tcx, gen_params, gen_args, gen_pos);
-
- let mut invalid_args = vec![];
-
- let mut check_lifetime_args =
- |min_expected_args: usize,
- max_expected_args: usize,
- provided_args: usize,
- late_bounds_ignore: bool| {
- if (min_expected_args..=max_expected_args).contains(&provided_args) {
- return Ok(());
- }
-
- if late_bounds_ignore {
- return Ok(());
- }
-
- if provided_args > max_expected_args {
- invalid_args.extend(
- gen_args.args[max_expected_args..provided_args]
- .iter()
- .map(|arg| arg.span()),
- );
- };
-
- let gen_args_info = if provided_args > min_expected_args {
- invalid_args.extend(
- gen_args.args[min_expected_args..provided_args]
- .iter()
- .map(|arg| arg.span()),
- );
- let num_redundant_args = provided_args - min_expected_args;
- GenericArgsInfo::ExcessLifetimes { num_redundant_args }
- } else {
- let num_missing_args = min_expected_args - provided_args;
- GenericArgsInfo::MissingLifetimes { num_missing_args }
- };
-
- let reported = WrongNumberOfGenericArgs::new(
- tcx,
- gen_args_info,
- seg,
- gen_params,
- has_self as usize,
- gen_args,
- def_id,
- )
- .diagnostic()
- .emit();
-
- Err(reported)
- };
-
- let min_expected_lifetime_args = if infer_lifetimes { 0 } else { param_counts.lifetimes };
- let max_expected_lifetime_args = param_counts.lifetimes;
- let num_provided_lifetime_args = gen_args.num_lifetime_params();
-
- let lifetimes_correct = check_lifetime_args(
- min_expected_lifetime_args,
- max_expected_lifetime_args,
- num_provided_lifetime_args,
- explicit_late_bound == ExplicitLateBound::Yes,
- );
-
- let mut check_types_and_consts = |expected_min,
- expected_max,
- expected_max_with_synth,
- provided,
- params_offset,
- args_offset| {
- debug!(
- ?expected_min,
- ?expected_max,
- ?provided,
- ?params_offset,
- ?args_offset,
- "check_types_and_consts"
- );
- if (expected_min..=expected_max).contains(&provided) {
- return Ok(());
- }
-
- let num_default_params = expected_max - expected_min;
-
- let gen_args_info = if provided > expected_max {
- invalid_args.extend(
- gen_args.args[args_offset + expected_max..args_offset + provided]
- .iter()
- .map(|arg| arg.span()),
- );
- let num_redundant_args = provided - expected_max;
-
- // Provide extra note if synthetic arguments like `impl Trait` are specified.
- let synth_provided = provided <= expected_max_with_synth;
-
- GenericArgsInfo::ExcessTypesOrConsts {
- num_redundant_args,
- num_default_params,
- args_offset,
- synth_provided,
- }
- } else {
- let num_missing_args = expected_max - provided;
-
- GenericArgsInfo::MissingTypesOrConsts {
- num_missing_args,
- num_default_params,
- args_offset,
- }
- };
-
- debug!(?gen_args_info);
-
- let reported = WrongNumberOfGenericArgs::new(
- tcx,
- gen_args_info,
- seg,
- gen_params,
- params_offset,
- gen_args,
- def_id,
- )
- .diagnostic()
- .emit_unless(gen_args.has_err());
-
- Err(reported)
- };
-
- let args_correct = {
- let expected_min = if infer_args {
- 0
- } else {
- param_counts.consts + named_type_param_count
- - default_counts.types
- - default_counts.consts
- };
- debug!(?expected_min);
- debug!(arg_counts.lifetimes=?gen_args.num_lifetime_params());
-
- check_types_and_consts(
- expected_min,
- param_counts.consts + named_type_param_count,
- param_counts.consts + named_type_param_count + synth_type_param_count,
- gen_args.num_generic_params(),
- param_counts.lifetimes + has_self as usize,
- gen_args.num_lifetime_params(),
- )
- };
-
- GenericArgCountResult {
- explicit_late_bound,
- correct: lifetimes_correct.and(args_correct).map_err(|reported| {
- GenericArgCountMismatch { reported: Some(reported), invalid_args }
- }),
- }
- }
-
- /// Emits an error regarding forbidden type binding associations
- pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_>, span: Span) {
- tcx.sess.emit_err(AssocTypeBindingNotAllowed { span });
- }
-
- /// Prohibits explicit lifetime arguments if late-bound lifetime parameters
- /// are present. This is used both for datatypes and function calls.
- pub(crate) fn prohibit_explicit_late_bound_lifetimes(
- tcx: TyCtxt<'_>,
- def: &ty::Generics,
- args: &hir::GenericArgs<'_>,
- position: GenericArgPosition,
- ) -> ExplicitLateBound {
- let param_counts = def.own_counts();
- let infer_lifetimes = position != GenericArgPosition::Type && !args.has_lifetime_params();
-
- if infer_lifetimes {
- return ExplicitLateBound::No;
- }
-
- if let Some(span_late) = def.has_late_bound_regions {
- let msg = "cannot specify lifetime arguments explicitly \
- if late bound lifetime parameters are present";
- let note = "the late bound lifetime parameter is introduced here";
- let span = args.args[0].span();
-
- if position == GenericArgPosition::Value
- && args.num_lifetime_params() != param_counts.lifetimes
- {
- let mut err = tcx.sess.struct_span_err(span, msg);
- err.span_note(span_late, note);
- err.emit();
- } else {
- let mut multispan = MultiSpan::from_span(span);
- multispan.push_span_label(span_late, note);
- tcx.struct_span_lint_hir(
- LATE_BOUND_LIFETIME_ARGUMENTS,
- args.args[0].hir_id(),
- multispan,
- |lint| {
- lint.build(msg).emit();
- },
- );
- }
-
- ExplicitLateBound::Yes
- } else {
- ExplicitLateBound::No
- }
- }
-}
projects / rustc.git / blobdiff