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Improve suggestion for calling closure on type mismatch

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This commit is contained in:
Michael Goulet 2022-06-19 23:11:31 -07:00
parent dc80ca78b6
commit d15fed79b8
11 changed files with 143 additions and 125 deletions
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189
compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
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@ -8,15 +8,14 @@ use rustc_hir as hir;
use rustc_hir::def::{CtorOf, DefKind};
use rustc_hir::lang_items::LangItem;
use rustc_hir::{
Expr, ExprKind, GenericBound, ItemKind, Node, Path, QPath, Stmt, StmtKind, TyKind,
WherePredicate,
Expr, ExprKind, GenericBound, Node, Path, QPath, Stmt, StmtKind, TyKind, WherePredicate,
};
use rustc_infer::infer::{self, TyCtxtInferExt};
use rustc_infer::traits;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::{self, Binder, IsSuggestable, ToPredicate, Ty};
use rustc_span::symbol::{kw, sym};
use rustc_middle::ty::{self, Binder, IsSuggestable, Subst, ToPredicate, Ty};
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
@ -78,124 +77,88 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
expected: Ty<'tcx>,
found: Ty<'tcx>,
) -> bool {
let hir = self.tcx.hir();
let (def_id, sig) = match *found.kind() {
ty::FnDef(def_id, _) => (def_id, found.fn_sig(self.tcx)),
ty::Closure(def_id, substs) => (def_id, substs.as_closure().sig()),
let (def_id, output, inputs) = match *found.kind() {
ty::FnDef(def_id, _) => {
let fn_sig = found.fn_sig(self.tcx);
(def_id, fn_sig.output(), fn_sig.inputs().skip_binder().len())
}
ty::Closure(def_id, substs) => {
let fn_sig = substs.as_closure().sig();
(def_id, fn_sig.output(), fn_sig.inputs().skip_binder().len() - 1)
}
ty::Opaque(def_id, substs) => {
let sig = self.tcx.bound_item_bounds(def_id).subst(self.tcx, substs).iter().find_map(|pred| {
if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder()
&& Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output()
// args tuple will always be substs[1]
&& let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind()
{
Some((
pred.kind().rebind(proj.term.ty().unwrap()),
args.len(),
))
} else {
None
}
});
if let Some((output, inputs)) = sig {
(def_id, output, inputs)
} else {
return false;
}
}
_ => return false,
};
let sig = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, sig);
let sig = self.normalize_associated_types_in(expr.span, sig);
if self.can_coerce(sig.output(), expected) {
let (mut sugg_call, applicability) = if sig.inputs().is_empty() {
(String::new(), Applicability::MachineApplicable)
} else {
("...".to_string(), Applicability::HasPlaceholders)
let output = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, output);
let output = self.normalize_associated_types_in(expr.span, output);
if !output.is_ty_var() && self.can_coerce(output, expected) {
let (sugg_call, mut applicability) = match inputs {
0 => ("".to_string(), Applicability::MachineApplicable),
1..=4 => (
(0..inputs).map(|_| "_").collect::<Vec<_>>().join(", "),
Applicability::MachineApplicable,
),
_ => ("...".to_string(), Applicability::HasPlaceholders),
};
let mut msg = "call this function";
match hir.get_if_local(def_id) {
Some(
Node::Item(hir::Item { kind: ItemKind::Fn(.., body_id), .. })
| Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Fn(_, body_id), ..
})
| Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Provided(body_id)),
..
}),
) => {
let body = hir.body(*body_id);
sugg_call = body
.params
.iter()
.map(|param| match &param.pat.kind {
hir::PatKind::Binding(_, _, ident, None)
if ident.name != kw::SelfLower =>
{
ident.to_string()
}
_ => "_".to_string(),
})
.collect::<Vec<_>>()
.join(", ");
let msg = match self.tcx.def_kind(def_id) {
DefKind::Fn => "call this function",
DefKind::Closure | DefKind::OpaqueTy => "call this closure",
DefKind::Ctor(CtorOf::Struct, _) => "instantiate this tuple struct",
DefKind::Ctor(CtorOf::Variant, _) => "instantiate this tuple variant",
_ => "call this function",
};
let sugg = match expr.kind {
hir::ExprKind::Call(..)
| hir::ExprKind::Path(..)
| hir::ExprKind::Index(..)
| hir::ExprKind::Lit(..) => {
vec![(expr.span.shrink_to_hi(), format!("({sugg_call})"))]
}
Some(Node::Expr(hir::Expr {
kind: ExprKind::Closure { body: body_id, .. },
span: full_closure_span,
..
})) => {
if *full_closure_span == expr.span {
return false;
}
msg = "call this closure";
let body = hir.body(*body_id);
sugg_call = body
.params
.iter()
.map(|param| match &param.pat.kind {
hir::PatKind::Binding(_, _, ident, None)
if ident.name != kw::SelfLower =>
{
ident.to_string()
}
_ => "_".to_string(),
})
.collect::<Vec<_>>()
.join(", ");
hir::ExprKind::Closure { .. } => {
// Might be `{ expr } || { bool }`
applicability = Applicability::MaybeIncorrect;
vec![
(expr.span.shrink_to_lo(), "(".to_string()),
(expr.span.shrink_to_hi(), format!(")({sugg_call})")),
]
}
Some(Node::Ctor(hir::VariantData::Tuple(fields, _))) => {
sugg_call = fields.iter().map(|_| "_").collect::<Vec<_>>().join(", ");
match def_id.as_local().map(|def_id| self.tcx.def_kind(def_id)) {
Some(DefKind::Ctor(hir::def::CtorOf::Variant, _)) => {
msg = "instantiate this tuple variant";
}
Some(DefKind::Ctor(CtorOf::Struct, _)) => {
msg = "instantiate this tuple struct";
}
_ => {}
}
_ => {
vec![
(expr.span.shrink_to_lo(), "(".to_string()),
(expr.span.shrink_to_hi(), format!(")({sugg_call})")),
]
}
Some(Node::ForeignItem(hir::ForeignItem {
kind: hir::ForeignItemKind::Fn(_, idents, _),
..
})) => {
sugg_call = idents
.iter()
.map(|ident| {
if ident.name != kw::SelfLower {
ident.to_string()
} else {
"_".to_string()
}
})
.collect::<Vec<_>>()
.join(", ")
}
Some(Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(.., hir::TraitFn::Required(idents)),
..
})) => {
sugg_call = idents
.iter()
.map(|ident| {
if ident.name != kw::SelfLower {
ident.to_string()
} else {
"_".to_string()
}
})
.collect::<Vec<_>>()
.join(", ")
}
_ => {}
}
err.span_suggestion_verbose(
expr.span.shrink_to_hi(),
&format!("use parentheses to {}", msg),
format!("({})", sugg_call),
};
err.multipart_suggestion_verbose(
format!("use parentheses to {msg}"),
sugg,
applicability,
);
return true;
}
false