bjoernager/rust
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Suggest collecting into Vec<_>

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This commit is contained in:
Esteban Küber 2022-12-09 22:31:16 -08:00
parent ed620cf969
commit 9d5e7d3c04
20 changed files with 49 additions and 31 deletions
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32
compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
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@ -20,7 +20,7 @@ use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter, Print, Printer};
use rustc_middle::ty::{self, DefIdTree, InferConst};
use rustc_middle::ty::{GenericArg, GenericArgKind, SubstsRef};
use rustc_middle::ty::{IsSuggestable, Ty, TyCtxt, TypeckResults};
use rustc_span::symbol::{kw, Ident};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{BytePos, Span};
use std::borrow::Cow;
use std::iter;
@ -78,12 +78,12 @@ impl InferenceDiagnosticsData {
}
fn where_x_is_kind(&self, in_type: Ty<'_>) -> &'static str {
if in_type.is_ty_infer() {
"empty"
} else if self.name == "_" {
if self.name == "_" {
// FIXME: Consider specializing this message if there is a single `_`
// in the type.
"underscore"
} else if in_type.is_ty_infer() {
"empty"
} else {
"has_name"
}
@ -368,6 +368,7 @@ impl<'tcx> InferCtxt<'tcx> {
}
impl<'tcx> TypeErrCtxt<'_, 'tcx> {
#[instrument(level = "debug", skip(self, error_code))]
pub fn emit_inference_failure_err(
&self,
body_id: Option<hir::BodyId>,
@ -406,16 +407,20 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
let mut infer_subdiags = Vec::new();
let mut multi_suggestions = Vec::new();
match kind {
InferSourceKind::LetBinding { insert_span, pattern_name, ty } => {
InferSourceKind::LetBinding { insert_span, pattern_name, ty, is_collect } => {
infer_subdiags.push(SourceKindSubdiag::LetLike {
span: insert_span,
name: pattern_name.map(|name| name.to_string()).unwrap_or_else(String::new),
x_kind: arg_data.where_x_is_kind(ty),
x_kind: if is_collect { "empty" } else { arg_data.where_x_is_kind(ty) },
prefix_kind: arg_data.kind.clone(),
prefix: arg_data.kind.try_get_prefix().unwrap_or_default(),
arg_name: arg_data.name,
kind: if pattern_name.is_some() { "with_pattern" } else { "other" },
type_name: ty_to_string(self, ty),
type_name: if is_collect {
"Vec<_>".to_string()
} else {
ty_to_string(self, ty)
},
});
}
InferSourceKind::ClosureArg { insert_span, ty } => {
@ -608,6 +613,7 @@ enum InferSourceKind<'tcx> {
insert_span: Span,
pattern_name: Option<Ident>,
ty: Ty<'tcx>,
is_collect: bool,
},
ClosureArg {
insert_span: Span,
@ -788,10 +794,19 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
/// Uses `fn source_cost` to determine whether this inference source is preferable to
/// previous sources. We generally prefer earlier sources.
#[instrument(level = "debug", skip(self))]
fn update_infer_source(&mut self, new_source: InferSource<'tcx>) {
fn update_infer_source(&mut self, mut new_source: InferSource<'tcx>) {
let cost = self.source_cost(&new_source) + self.attempt;
debug!(?cost);
self.attempt += 1;
if let Some(InferSource { kind: InferSourceKind::GenericArg { def_id, ..}, .. }) = self.infer_source
&& self.infcx.tcx.get_diagnostic_item(sym::iterator_collect_fn) == Some(def_id)
&& let InferSourceKind::LetBinding { ref ty, ref mut is_collect, ..} = new_source.kind
&& ty.is_ty_infer()
{
// Customize the output so we talk about `let x: Vec<_> = iter.collect();` instead of
// `let x: _ = iter.collect();`, as this is a very common case.
*is_collect = true;
}
if cost < self.infer_source_cost {
self.infer_source_cost = cost;
self.infer_source = Some(new_source);
@ -1089,6 +1104,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
insert_span: local.pat.span.shrink_to_hi(),
pattern_name: local.pat.simple_ident(),
ty,
is_collect: false,
},
})
}