mv compiler to compiler/
This commit is contained in:
mark
Vadim Petrochenkov
parent
db534b3ac2
commit
9e5f7d5631
1686 changed files with 941 additions and 1051 deletions
897
compiler/rustc_middle/src/ty/error.rs
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897
compiler/rustc_middle/src/ty/error.rs
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@ -0,0 +1,897 @@
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use crate::traits::{ObligationCause, ObligationCauseCode};
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use crate::ty::diagnostics::suggest_constraining_type_param;
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use crate::ty::{self, BoundRegion, Region, Ty, TyCtxt};
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use rustc_ast as ast;
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use rustc_errors::Applicability::{MachineApplicable, MaybeIncorrect};
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use rustc_errors::{pluralize, DiagnosticBuilder};
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use rustc_hir as hir;
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use rustc_hir::def_id::DefId;
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use rustc_span::symbol::{sym, Symbol};
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use rustc_span::{BytePos, MultiSpan, Span};
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use rustc_target::spec::abi;
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use std::borrow::Cow;
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use std::fmt;
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use std::ops::Deref;
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#[derive(Clone, Copy, Debug, PartialEq, Eq, TypeFoldable)]
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pub struct ExpectedFound<T> {
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pub expected: T,
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pub found: T,
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}
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impl<T> ExpectedFound<T> {
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pub fn new(a_is_expected: bool, a: T, b: T) -> Self {
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if a_is_expected {
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ExpectedFound { expected: a, found: b }
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} else {
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ExpectedFound { expected: b, found: a }
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}
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}
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}
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// Data structures used in type unification
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#[derive(Clone, Debug, TypeFoldable)]
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pub enum TypeError<'tcx> {
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Mismatch,
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UnsafetyMismatch(ExpectedFound<hir::Unsafety>),
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AbiMismatch(ExpectedFound<abi::Abi>),
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Mutability,
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TupleSize(ExpectedFound<usize>),
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FixedArraySize(ExpectedFound<u64>),
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ArgCount,
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RegionsDoesNotOutlive(Region<'tcx>, Region<'tcx>),
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RegionsInsufficientlyPolymorphic(BoundRegion, Region<'tcx>),
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RegionsOverlyPolymorphic(BoundRegion, Region<'tcx>),
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RegionsPlaceholderMismatch,
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Sorts(ExpectedFound<Ty<'tcx>>),
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IntMismatch(ExpectedFound<ty::IntVarValue>),
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FloatMismatch(ExpectedFound<ast::FloatTy>),
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Traits(ExpectedFound<DefId>),
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VariadicMismatch(ExpectedFound<bool>),
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/// Instantiating a type variable with the given type would have
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/// created a cycle (because it appears somewhere within that
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/// type).
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CyclicTy(Ty<'tcx>),
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ProjectionMismatched(ExpectedFound<DefId>),
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ExistentialMismatch(ExpectedFound<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>),
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ObjectUnsafeCoercion(DefId),
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ConstMismatch(ExpectedFound<&'tcx ty::Const<'tcx>>),
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IntrinsicCast,
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/// Safe `#[target_feature]` functions are not assignable to safe function pointers.
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TargetFeatureCast(DefId),
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}
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pub enum UnconstrainedNumeric {
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UnconstrainedFloat,
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UnconstrainedInt,
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Neither,
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}
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/// Explains the source of a type err in a short, human readable way. This is meant to be placed
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/// in parentheses after some larger message. You should also invoke `note_and_explain_type_err()`
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/// afterwards to present additional details, particularly when it comes to lifetime-related
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/// errors.
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impl<'tcx> fmt::Display for TypeError<'tcx> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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use self::TypeError::*;
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fn report_maybe_different(
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f: &mut fmt::Formatter<'_>,
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expected: &str,
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found: &str,
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) -> fmt::Result {
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// A naive approach to making sure that we're not reporting silly errors such as:
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// (expected closure, found closure).
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if expected == found {
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write!(f, "expected {}, found a different {}", expected, found)
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} else {
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write!(f, "expected {}, found {}", expected, found)
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}
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}
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let br_string = |br: ty::BoundRegion| match br {
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ty::BrNamed(_, name) => format!(" {}", name),
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_ => String::new(),
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};
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match *self {
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CyclicTy(_) => write!(f, "cyclic type of infinite size"),
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Mismatch => write!(f, "types differ"),
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UnsafetyMismatch(values) => {
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write!(f, "expected {} fn, found {} fn", values.expected, values.found)
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}
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AbiMismatch(values) => {
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write!(f, "expected {} fn, found {} fn", values.expected, values.found)
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}
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Mutability => write!(f, "types differ in mutability"),
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TupleSize(values) => write!(
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f,
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"expected a tuple with {} element{}, \
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found one with {} element{}",
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values.expected,
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pluralize!(values.expected),
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values.found,
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pluralize!(values.found)
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),
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FixedArraySize(values) => write!(
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f,
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"expected an array with a fixed size of {} element{}, \
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found one with {} element{}",
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values.expected,
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pluralize!(values.expected),
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values.found,
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pluralize!(values.found)
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),
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ArgCount => write!(f, "incorrect number of function parameters"),
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RegionsDoesNotOutlive(..) => write!(f, "lifetime mismatch"),
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RegionsInsufficientlyPolymorphic(br, _) => write!(
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f,
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"expected bound lifetime parameter{}, found concrete lifetime",
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br_string(br)
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),
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RegionsOverlyPolymorphic(br, _) => write!(
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f,
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"expected concrete lifetime, found bound lifetime parameter{}",
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br_string(br)
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),
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RegionsPlaceholderMismatch => write!(f, "one type is more general than the other"),
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Sorts(values) => ty::tls::with(|tcx| {
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report_maybe_different(
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f,
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&values.expected.sort_string(tcx),
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&values.found.sort_string(tcx),
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)
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}),
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Traits(values) => ty::tls::with(|tcx| {
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report_maybe_different(
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f,
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&format!("trait `{}`", tcx.def_path_str(values.expected)),
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&format!("trait `{}`", tcx.def_path_str(values.found)),
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)
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}),
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IntMismatch(ref values) => {
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write!(f, "expected `{:?}`, found `{:?}`", values.expected, values.found)
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}
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FloatMismatch(ref values) => {
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write!(f, "expected `{:?}`, found `{:?}`", values.expected, values.found)
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}
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VariadicMismatch(ref values) => write!(
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f,
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"expected {} fn, found {} function",
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if values.expected { "variadic" } else { "non-variadic" },
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if values.found { "variadic" } else { "non-variadic" }
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),
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ProjectionMismatched(ref values) => ty::tls::with(|tcx| {
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write!(
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f,
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"expected {}, found {}",
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tcx.def_path_str(values.expected),
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tcx.def_path_str(values.found)
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)
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}),
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ExistentialMismatch(ref values) => report_maybe_different(
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f,
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&format!("trait `{}`", values.expected),
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&format!("trait `{}`", values.found),
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),
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ConstMismatch(ref values) => {
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write!(f, "expected `{}`, found `{}`", values.expected, values.found)
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}
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IntrinsicCast => write!(f, "cannot coerce intrinsics to function pointers"),
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TargetFeatureCast(_) => write!(
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f,
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"cannot coerce functions with `#[target_feature]` to safe function pointers"
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),
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ObjectUnsafeCoercion(_) => write!(f, "coercion to object-unsafe trait object"),
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}
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}
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}
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impl<'tcx> TypeError<'tcx> {
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pub fn must_include_note(&self) -> bool {
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use self::TypeError::*;
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match self {
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CyclicTy(_) | UnsafetyMismatch(_) | Mismatch | AbiMismatch(_) | FixedArraySize(_)
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| Sorts(_) | IntMismatch(_) | FloatMismatch(_) | VariadicMismatch(_)
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| TargetFeatureCast(_) => false,
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Mutability
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| TupleSize(_)
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| ArgCount
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| RegionsDoesNotOutlive(..)
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| RegionsInsufficientlyPolymorphic(..)
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| RegionsOverlyPolymorphic(..)
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| RegionsPlaceholderMismatch
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| Traits(_)
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| ProjectionMismatched(_)
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| ExistentialMismatch(_)
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| ConstMismatch(_)
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| IntrinsicCast
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| ObjectUnsafeCoercion(_) => true,
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}
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}
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}
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impl<'tcx> ty::TyS<'tcx> {
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pub fn sort_string(&self, tcx: TyCtxt<'_>) -> Cow<'static, str> {
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match self.kind {
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ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str | ty::Never => {
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format!("`{}`", self).into()
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}
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ty::Tuple(ref tys) if tys.is_empty() => format!("`{}`", self).into(),
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ty::Adt(def, _) => format!("{} `{}`", def.descr(), tcx.def_path_str(def.did)).into(),
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ty::Foreign(def_id) => format!("extern type `{}`", tcx.def_path_str(def_id)).into(),
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ty::Array(t, n) => {
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let n = tcx.lift(&n).unwrap();
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match n.try_eval_usize(tcx, ty::ParamEnv::empty()) {
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_ if t.is_simple_ty() => format!("array `{}`", self).into(),
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Some(n) => format!("array of {} element{} ", n, pluralize!(n)).into(),
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None => "array".into(),
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}
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}
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ty::Slice(ty) if ty.is_simple_ty() => format!("slice `{}`", self).into(),
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ty::Slice(_) => "slice".into(),
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ty::RawPtr(_) => "*-ptr".into(),
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ty::Ref(_, ty, mutbl) => {
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let tymut = ty::TypeAndMut { ty, mutbl };
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let tymut_string = tymut.to_string();
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if tymut_string != "_"
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&& (ty.is_simple_text() || tymut_string.len() < "mutable reference".len())
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{
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format!("`&{}`", tymut_string).into()
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} else {
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// Unknown type name, it's long or has type arguments
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match mutbl {
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hir::Mutability::Mut => "mutable reference",
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_ => "reference",
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}
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.into()
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}
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}
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ty::FnDef(..) => "fn item".into(),
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ty::FnPtr(_) => "fn pointer".into(),
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ty::Dynamic(ref inner, ..) => {
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if let Some(principal) = inner.principal() {
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format!("trait object `dyn {}`", tcx.def_path_str(principal.def_id())).into()
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} else {
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"trait object".into()
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}
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}
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ty::Closure(..) => "closure".into(),
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ty::Generator(..) => "generator".into(),
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ty::GeneratorWitness(..) => "generator witness".into(),
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ty::Tuple(..) => "tuple".into(),
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ty::Infer(ty::TyVar(_)) => "inferred type".into(),
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ty::Infer(ty::IntVar(_)) => "integer".into(),
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ty::Infer(ty::FloatVar(_)) => "floating-point number".into(),
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ty::Placeholder(..) => "placeholder type".into(),
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ty::Bound(..) => "bound type".into(),
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ty::Infer(ty::FreshTy(_)) => "fresh type".into(),
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ty::Infer(ty::FreshIntTy(_)) => "fresh integral type".into(),
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ty::Infer(ty::FreshFloatTy(_)) => "fresh floating-point type".into(),
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ty::Projection(_) => "associated type".into(),
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ty::Param(p) => format!("type parameter `{}`", p).into(),
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ty::Opaque(..) => "opaque type".into(),
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ty::Error(_) => "type error".into(),
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}
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}
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pub fn prefix_string(&self) -> Cow<'static, str> {
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match self.kind {
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ty::Infer(_)
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| ty::Error(_)
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| ty::Bool
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| ty::Char
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| ty::Int(_)
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| ty::Uint(_)
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| ty::Float(_)
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| ty::Str
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| ty::Never => "type".into(),
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ty::Tuple(ref tys) if tys.is_empty() => "unit type".into(),
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ty::Adt(def, _) => def.descr().into(),
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ty::Foreign(_) => "extern type".into(),
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ty::Array(..) => "array".into(),
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ty::Slice(_) => "slice".into(),
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ty::RawPtr(_) => "raw pointer".into(),
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ty::Ref(.., mutbl) => match mutbl {
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hir::Mutability::Mut => "mutable reference",
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_ => "reference",
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}
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.into(),
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ty::FnDef(..) => "fn item".into(),
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ty::FnPtr(_) => "fn pointer".into(),
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ty::Dynamic(..) => "trait object".into(),
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ty::Closure(..) => "closure".into(),
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ty::Generator(..) => "generator".into(),
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ty::GeneratorWitness(..) => "generator witness".into(),
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ty::Tuple(..) => "tuple".into(),
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ty::Placeholder(..) => "higher-ranked type".into(),
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ty::Bound(..) => "bound type variable".into(),
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ty::Projection(_) => "associated type".into(),
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ty::Param(_) => "type parameter".into(),
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ty::Opaque(..) => "opaque type".into(),
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}
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}
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}
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impl<'tcx> TyCtxt<'tcx> {
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pub fn note_and_explain_type_err(
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self,
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db: &mut DiagnosticBuilder<'_>,
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err: &TypeError<'tcx>,
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cause: &ObligationCause<'tcx>,
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sp: Span,
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body_owner_def_id: DefId,
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) {
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use self::TypeError::*;
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debug!("note_and_explain_type_err err={:?} cause={:?}", err, cause);
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match err {
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Sorts(values) => {
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let expected_str = values.expected.sort_string(self);
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let found_str = values.found.sort_string(self);
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if expected_str == found_str && expected_str == "closure" {
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db.note("no two closures, even if identical, have the same type");
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db.help("consider boxing your closure and/or using it as a trait object");
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}
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if expected_str == found_str && expected_str == "opaque type" {
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// Issue #63167
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db.note("distinct uses of `impl Trait` result in different opaque types");
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let e_str = values.expected.to_string();
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let f_str = values.found.to_string();
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if e_str == f_str && &e_str == "impl std::future::Future" {
|
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// FIXME: use non-string based check.
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db.help(
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"if both `Future`s have the same `Output` type, consider \
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`.await`ing on both of them",
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);
|
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}
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}
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match (&values.expected.kind, &values.found.kind) {
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(ty::Float(_), ty::Infer(ty::IntVar(_))) => {
|
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if let Ok(
|
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// Issue #53280
|
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snippet,
|
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) = self.sess.source_map().span_to_snippet(sp)
|
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{
|
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if snippet.chars().all(|c| c.is_digit(10) || c == '-' || c == '_') {
|
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db.span_suggestion(
|
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sp,
|
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"use a float literal",
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format!("{}.0", snippet),
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MachineApplicable,
|
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);
|
||||
}
|
||||
}
|
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}
|
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(ty::Param(expected), ty::Param(found)) => {
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let generics = self.generics_of(body_owner_def_id);
|
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let e_span = self.def_span(generics.type_param(expected, self).def_id);
|
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if !sp.contains(e_span) {
|
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db.span_label(e_span, "expected type parameter");
|
||||
}
|
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let f_span = self.def_span(generics.type_param(found, self).def_id);
|
||||
if !sp.contains(f_span) {
|
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db.span_label(f_span, "found type parameter");
|
||||
}
|
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db.note(
|
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"a type parameter was expected, but a different one was found; \
|
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you might be missing a type parameter or trait bound",
|
||||
);
|
||||
db.note(
|
||||
"for more information, visit \
|
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https://doc.rust-lang.org/book/ch10-02-traits.html\
|
||||
#traits-as-parameters",
|
||||
);
|
||||
}
|
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(ty::Projection(_), ty::Projection(_)) => {
|
||||
db.note("an associated type was expected, but a different one was found");
|
||||
}
|
||||
(ty::Param(p), ty::Projection(proj)) | (ty::Projection(proj), ty::Param(p)) => {
|
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let generics = self.generics_of(body_owner_def_id);
|
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let p_span = self.def_span(generics.type_param(p, self).def_id);
|
||||
if !sp.contains(p_span) {
|
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db.span_label(p_span, "this type parameter");
|
||||
}
|
||||
let hir = self.hir();
|
||||
let mut note = true;
|
||||
if let Some(generics) = generics
|
||||
.type_param(p, self)
|
||||
.def_id
|
||||
.as_local()
|
||||
.map(|id| hir.local_def_id_to_hir_id(id))
|
||||
.and_then(|id| self.hir().find(self.hir().get_parent_node(id)))
|
||||
.as_ref()
|
||||
.and_then(|node| node.generics())
|
||||
{
|
||||
// Synthesize the associated type restriction `Add<Output = Expected>`.
|
||||
// FIXME: extract this logic for use in other diagnostics.
|
||||
let trait_ref = proj.trait_ref(self);
|
||||
let path =
|
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self.def_path_str_with_substs(trait_ref.def_id, trait_ref.substs);
|
||||
let item_name = self.item_name(proj.item_def_id);
|
||||
let path = if path.ends_with('>') {
|
||||
format!("{}, {} = {}>", &path[..path.len() - 1], item_name, p)
|
||||
} else {
|
||||
format!("{}<{} = {}>", path, item_name, p)
|
||||
};
|
||||
note = !suggest_constraining_type_param(
|
||||
self,
|
||||
generics,
|
||||
db,
|
||||
&format!("{}", proj.self_ty()),
|
||||
&path,
|
||||
None,
|
||||
);
|
||||
}
|
||||
if note {
|
||||
db.note("you might be missing a type parameter or trait bound");
|
||||
}
|
||||
}
|
||||
(ty::Param(p), ty::Dynamic(..) | ty::Opaque(..))
|
||||
| (ty::Dynamic(..) | ty::Opaque(..), ty::Param(p)) => {
|
||||
let generics = self.generics_of(body_owner_def_id);
|
||||
let p_span = self.def_span(generics.type_param(p, self).def_id);
|
||||
if !sp.contains(p_span) {
|
||||
db.span_label(p_span, "this type parameter");
|
||||
}
|
||||
db.help("type parameters must be constrained to match other types");
|
||||
if self.sess.teach(&db.get_code().unwrap()) {
|
||||
db.help(
|
||||
"given a type parameter `T` and a method `foo`:
|
||||
```
|
||||
trait Trait<T> { fn foo(&self) -> T; }
|
||||
```
|
||||
the only ways to implement method `foo` are:
|
||||
- constrain `T` with an explicit type:
|
||||
```
|
||||
impl Trait<String> for X {
|
||||
fn foo(&self) -> String { String::new() }
|
||||
}
|
||||
```
|
||||
- add a trait bound to `T` and call a method on that trait that returns `Self`:
|
||||
```
|
||||
impl<T: std::default::Default> Trait<T> for X {
|
||||
fn foo(&self) -> T { <T as std::default::Default>::default() }
|
||||
}
|
||||
```
|
||||
- change `foo` to return an argument of type `T`:
|
||||
```
|
||||
impl<T> Trait<T> for X {
|
||||
fn foo(&self, x: T) -> T { x }
|
||||
}
|
||||
```",
|
||||
);
|
||||
}
|
||||
db.note(
|
||||
"for more information, visit \
|
||||
https://doc.rust-lang.org/book/ch10-02-traits.html\
|
||||
#traits-as-parameters",
|
||||
);
|
||||
}
|
||||
(ty::Param(p), _) | (_, ty::Param(p)) => {
|
||||
let generics = self.generics_of(body_owner_def_id);
|
||||
let p_span = self.def_span(generics.type_param(p, self).def_id);
|
||||
if !sp.contains(p_span) {
|
||||
db.span_label(p_span, "this type parameter");
|
||||
}
|
||||
}
|
||||
(ty::Projection(proj_ty), _) => {
|
||||
self.expected_projection(
|
||||
db,
|
||||
proj_ty,
|
||||
values,
|
||||
body_owner_def_id,
|
||||
&cause.code,
|
||||
);
|
||||
}
|
||||
(_, ty::Projection(proj_ty)) => {
|
||||
let msg = format!(
|
||||
"consider constraining the associated type `{}` to `{}`",
|
||||
values.found, values.expected,
|
||||
);
|
||||
if !self.suggest_constraint(
|
||||
db,
|
||||
&msg,
|
||||
body_owner_def_id,
|
||||
proj_ty,
|
||||
values.expected,
|
||||
) {
|
||||
db.help(&msg);
|
||||
db.note(
|
||||
"for more information, visit \
|
||||
https://doc.rust-lang.org/book/ch19-03-advanced-traits.html",
|
||||
);
|
||||
}
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
debug!(
|
||||
"note_and_explain_type_err expected={:?} ({:?}) found={:?} ({:?})",
|
||||
values.expected, values.expected.kind, values.found, values.found.kind,
|
||||
);
|
||||
}
|
||||
CyclicTy(ty) => {
|
||||
// Watch out for various cases of cyclic types and try to explain.
|
||||
if ty.is_closure() || ty.is_generator() {
|
||||
db.note(
|
||||
"closures cannot capture themselves or take themselves as argument;\n\
|
||||
this error may be the result of a recent compiler bug-fix,\n\
|
||||
see issue #46062 <https://github.com/rust-lang/rust/issues/46062>\n\
|
||||
for more information",
|
||||
);
|
||||
}
|
||||
}
|
||||
TargetFeatureCast(def_id) => {
|
||||
let attrs = self.get_attrs(*def_id);
|
||||
let target_spans = attrs
|
||||
.deref()
|
||||
.iter()
|
||||
.filter(|attr| attr.has_name(sym::target_feature))
|
||||
.map(|attr| attr.span);
|
||||
db.note(
|
||||
"functions with `#[target_feature]` can only be coerced to `unsafe` function pointers"
|
||||
);
|
||||
db.span_labels(target_spans, "`#[target_feature]` added here");
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
|
||||
fn suggest_constraint(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
msg: &str,
|
||||
body_owner_def_id: DefId,
|
||||
proj_ty: &ty::ProjectionTy<'tcx>,
|
||||
ty: Ty<'tcx>,
|
||||
) -> bool {
|
||||
let assoc = self.associated_item(proj_ty.item_def_id);
|
||||
let trait_ref = proj_ty.trait_ref(*self);
|
||||
if let Some(item) = self.hir().get_if_local(body_owner_def_id) {
|
||||
if let Some(hir_generics) = item.generics() {
|
||||
// Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
|
||||
// This will also work for `impl Trait`.
|
||||
let def_id = if let ty::Param(param_ty) = proj_ty.self_ty().kind {
|
||||
let generics = self.generics_of(body_owner_def_id);
|
||||
generics.type_param(¶m_ty, *self).def_id
|
||||
} else {
|
||||
return false;
|
||||
};
|
||||
|
||||
// First look in the `where` clause, as this might be
|
||||
// `fn foo<T>(x: T) where T: Trait`.
|
||||
for predicate in hir_generics.where_clause.predicates {
|
||||
if let hir::WherePredicate::BoundPredicate(pred) = predicate {
|
||||
if let hir::TyKind::Path(hir::QPath::Resolved(None, path)) =
|
||||
pred.bounded_ty.kind
|
||||
{
|
||||
if path.res.opt_def_id() == Some(def_id) {
|
||||
// This predicate is binding type param `A` in `<A as T>::Foo` to
|
||||
// something, potentially `T`.
|
||||
} else {
|
||||
continue;
|
||||
}
|
||||
} else {
|
||||
continue;
|
||||
}
|
||||
|
||||
if self.constrain_generic_bound_associated_type_structured_suggestion(
|
||||
db,
|
||||
&trait_ref,
|
||||
pred.bounds,
|
||||
&assoc,
|
||||
ty,
|
||||
msg,
|
||||
) {
|
||||
return true;
|
||||
}
|
||||
}
|
||||
}
|
||||
for param in hir_generics.params {
|
||||
if self.hir().opt_local_def_id(param.hir_id).map(|id| id.to_def_id())
|
||||
== Some(def_id)
|
||||
{
|
||||
// This is type param `A` in `<A as T>::Foo`.
|
||||
return self.constrain_generic_bound_associated_type_structured_suggestion(
|
||||
db,
|
||||
&trait_ref,
|
||||
param.bounds,
|
||||
&assoc,
|
||||
ty,
|
||||
msg,
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
false
|
||||
}
|
||||
|
||||
/// An associated type was expected and a different type was found.
|
||||
///
|
||||
/// We perform a few different checks to see what we can suggest:
|
||||
///
|
||||
/// - In the current item, look for associated functions that return the expected type and
|
||||
/// suggest calling them. (Not a structured suggestion.)
|
||||
/// - If any of the item's generic bounds can be constrained, we suggest constraining the
|
||||
/// associated type to the found type.
|
||||
/// - If the associated type has a default type and was expected inside of a `trait`, we
|
||||
/// mention that this is disallowed.
|
||||
/// - If all other things fail, and the error is not because of a mismatch between the `trait`
|
||||
/// and the `impl`, we provide a generic `help` to constrain the assoc type or call an assoc
|
||||
/// fn that returns the type.
|
||||
fn expected_projection(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
proj_ty: &ty::ProjectionTy<'tcx>,
|
||||
values: &ExpectedFound<Ty<'tcx>>,
|
||||
body_owner_def_id: DefId,
|
||||
cause_code: &ObligationCauseCode<'_>,
|
||||
) {
|
||||
let msg = format!(
|
||||
"consider constraining the associated type `{}` to `{}`",
|
||||
values.expected, values.found
|
||||
);
|
||||
let body_owner = self.hir().get_if_local(body_owner_def_id);
|
||||
let current_method_ident = body_owner.and_then(|n| n.ident()).map(|i| i.name);
|
||||
|
||||
// We don't want to suggest calling an assoc fn in a scope where that isn't feasible.
|
||||
let callable_scope = match body_owner {
|
||||
Some(
|
||||
hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(..), .. })
|
||||
| hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
|
||||
| hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }),
|
||||
) => true,
|
||||
_ => false,
|
||||
};
|
||||
let impl_comparison = matches!(
|
||||
cause_code,
|
||||
ObligationCauseCode::CompareImplMethodObligation { .. }
|
||||
| ObligationCauseCode::CompareImplTypeObligation { .. }
|
||||
| ObligationCauseCode::CompareImplConstObligation
|
||||
);
|
||||
let assoc = self.associated_item(proj_ty.item_def_id);
|
||||
if !callable_scope || impl_comparison {
|
||||
// We do not want to suggest calling functions when the reason of the
|
||||
// type error is a comparison of an `impl` with its `trait` or when the
|
||||
// scope is outside of a `Body`.
|
||||
} else {
|
||||
// If we find a suitable associated function that returns the expected type, we don't
|
||||
// want the more general suggestion later in this method about "consider constraining
|
||||
// the associated type or calling a method that returns the associated type".
|
||||
let point_at_assoc_fn = self.point_at_methods_that_satisfy_associated_type(
|
||||
db,
|
||||
assoc.container.id(),
|
||||
current_method_ident,
|
||||
proj_ty.item_def_id,
|
||||
values.expected,
|
||||
);
|
||||
// Possibly suggest constraining the associated type to conform to the
|
||||
// found type.
|
||||
if self.suggest_constraint(db, &msg, body_owner_def_id, proj_ty, values.found)
|
||||
|| point_at_assoc_fn
|
||||
{
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
if let ty::Opaque(def_id, _) = proj_ty.self_ty().kind {
|
||||
// When the expected `impl Trait` is not defined in the current item, it will come from
|
||||
// a return type. This can occur when dealing with `TryStream` (#71035).
|
||||
if self.constrain_associated_type_structured_suggestion(
|
||||
db,
|
||||
self.def_span(def_id),
|
||||
&assoc,
|
||||
values.found,
|
||||
&msg,
|
||||
) {
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
if self.point_at_associated_type(db, body_owner_def_id, values.found) {
|
||||
return;
|
||||
}
|
||||
|
||||
if !impl_comparison {
|
||||
// Generic suggestion when we can't be more specific.
|
||||
if callable_scope {
|
||||
db.help(&format!("{} or calling a method that returns `{}`", msg, values.expected));
|
||||
} else {
|
||||
db.help(&msg);
|
||||
}
|
||||
db.note(
|
||||
"for more information, visit \
|
||||
https://doc.rust-lang.org/book/ch19-03-advanced-traits.html",
|
||||
);
|
||||
}
|
||||
if self.sess.teach(&db.get_code().unwrap()) {
|
||||
db.help(
|
||||
"given an associated type `T` and a method `foo`:
|
||||
```
|
||||
trait Trait {
|
||||
type T;
|
||||
fn foo(&self) -> Self::T;
|
||||
}
|
||||
```
|
||||
the only way of implementing method `foo` is to constrain `T` with an explicit associated type:
|
||||
```
|
||||
impl Trait for X {
|
||||
type T = String;
|
||||
fn foo(&self) -> Self::T { String::new() }
|
||||
}
|
||||
```",
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
fn point_at_methods_that_satisfy_associated_type(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
assoc_container_id: DefId,
|
||||
current_method_ident: Option<Symbol>,
|
||||
proj_ty_item_def_id: DefId,
|
||||
expected: Ty<'tcx>,
|
||||
) -> bool {
|
||||
let items = self.associated_items(assoc_container_id);
|
||||
// Find all the methods in the trait that could be called to construct the
|
||||
// expected associated type.
|
||||
// FIXME: consider suggesting the use of associated `const`s.
|
||||
let methods: Vec<(Span, String)> = items
|
||||
.items
|
||||
.iter()
|
||||
.filter(|(name, item)| {
|
||||
ty::AssocKind::Fn == item.kind && Some(**name) != current_method_ident
|
||||
})
|
||||
.filter_map(|(_, item)| {
|
||||
let method = self.fn_sig(item.def_id);
|
||||
match method.output().skip_binder().kind {
|
||||
ty::Projection(ty::ProjectionTy { item_def_id, .. })
|
||||
if item_def_id == proj_ty_item_def_id =>
|
||||
{
|
||||
Some((
|
||||
self.sess.source_map().guess_head_span(self.def_span(item.def_id)),
|
||||
format!("consider calling `{}`", self.def_path_str(item.def_id)),
|
||||
))
|
||||
}
|
||||
_ => None,
|
||||
}
|
||||
})
|
||||
.collect();
|
||||
if !methods.is_empty() {
|
||||
// Use a single `help:` to show all the methods in the trait that can
|
||||
// be used to construct the expected associated type.
|
||||
let mut span: MultiSpan =
|
||||
methods.iter().map(|(sp, _)| *sp).collect::<Vec<Span>>().into();
|
||||
let msg = format!(
|
||||
"{some} method{s} {are} available that return{r} `{ty}`",
|
||||
some = if methods.len() == 1 { "a" } else { "some" },
|
||||
s = pluralize!(methods.len()),
|
||||
are = if methods.len() == 1 { "is" } else { "are" },
|
||||
r = if methods.len() == 1 { "s" } else { "" },
|
||||
ty = expected
|
||||
);
|
||||
for (sp, label) in methods.into_iter() {
|
||||
span.push_span_label(sp, label);
|
||||
}
|
||||
db.span_help(span, &msg);
|
||||
return true;
|
||||
}
|
||||
false
|
||||
}
|
||||
|
||||
fn point_at_associated_type(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
body_owner_def_id: DefId,
|
||||
found: Ty<'tcx>,
|
||||
) -> bool {
|
||||
let hir_id =
|
||||
match body_owner_def_id.as_local().map(|id| self.hir().local_def_id_to_hir_id(id)) {
|
||||
Some(hir_id) => hir_id,
|
||||
None => return false,
|
||||
};
|
||||
// When `body_owner` is an `impl` or `trait` item, look in its associated types for
|
||||
// `expected` and point at it.
|
||||
let parent_id = self.hir().get_parent_item(hir_id);
|
||||
let item = self.hir().find(parent_id);
|
||||
debug!("expected_projection parent item {:?}", item);
|
||||
match item {
|
||||
Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., items), .. })) => {
|
||||
// FIXME: account for `#![feature(specialization)]`
|
||||
for item in &items[..] {
|
||||
match item.kind {
|
||||
hir::AssocItemKind::Type => {
|
||||
// FIXME: account for returning some type in a trait fn impl that has
|
||||
// an assoc type as a return type (#72076).
|
||||
if let hir::Defaultness::Default { has_value: true } = item.defaultness
|
||||
{
|
||||
if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found {
|
||||
db.span_label(
|
||||
item.span,
|
||||
"associated type defaults can't be assumed inside the \
|
||||
trait defining them",
|
||||
);
|
||||
return true;
|
||||
}
|
||||
}
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
}
|
||||
Some(hir::Node::Item(hir::Item {
|
||||
kind: hir::ItemKind::Impl { items, .. }, ..
|
||||
})) => {
|
||||
for item in &items[..] {
|
||||
match item.kind {
|
||||
hir::AssocItemKind::Type => {
|
||||
if self.type_of(self.hir().local_def_id(item.id.hir_id)) == found {
|
||||
db.span_label(item.span, "expected this associated type");
|
||||
return true;
|
||||
}
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
false
|
||||
}
|
||||
|
||||
/// Given a slice of `hir::GenericBound`s, if any of them corresponds to the `trait_ref`
|
||||
/// requirement, provide a strucuted suggestion to constrain it to a given type `ty`.
|
||||
fn constrain_generic_bound_associated_type_structured_suggestion(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
trait_ref: &ty::TraitRef<'tcx>,
|
||||
bounds: hir::GenericBounds<'_>,
|
||||
assoc: &ty::AssocItem,
|
||||
ty: Ty<'tcx>,
|
||||
msg: &str,
|
||||
) -> bool {
|
||||
// FIXME: we would want to call `resolve_vars_if_possible` on `ty` before suggesting.
|
||||
bounds.iter().any(|bound| match bound {
|
||||
hir::GenericBound::Trait(ptr, hir::TraitBoundModifier::None) => {
|
||||
// Relate the type param against `T` in `<A as T>::Foo`.
|
||||
ptr.trait_ref.trait_def_id() == Some(trait_ref.def_id)
|
||||
&& self.constrain_associated_type_structured_suggestion(
|
||||
db, ptr.span, assoc, ty, msg,
|
||||
)
|
||||
}
|
||||
_ => false,
|
||||
})
|
||||
}
|
||||
|
||||
/// Given a span corresponding to a bound, provide a structured suggestion to set an
|
||||
/// associated type to a given type `ty`.
|
||||
fn constrain_associated_type_structured_suggestion(
|
||||
&self,
|
||||
db: &mut DiagnosticBuilder<'_>,
|
||||
span: Span,
|
||||
assoc: &ty::AssocItem,
|
||||
ty: Ty<'tcx>,
|
||||
msg: &str,
|
||||
) -> bool {
|
||||
if let Ok(has_params) =
|
||||
self.sess.source_map().span_to_snippet(span).map(|snippet| snippet.ends_with('>'))
|
||||
{
|
||||
let (span, sugg) = if has_params {
|
||||
let pos = span.hi() - BytePos(1);
|
||||
let span = Span::new(pos, pos, span.ctxt());
|
||||
(span, format!(", {} = {}", assoc.ident, ty))
|
||||
} else {
|
||||
(span.shrink_to_hi(), format!("<{} = {}>", assoc.ident, ty))
|
||||
};
|
||||
db.span_suggestion_verbose(span, msg, sugg, MaybeIncorrect);
|
||||
return true;
|
||||
}
|
||||
false
|
||||
}
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue