bjoernager/rust
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Suggest the correct array length on mismatch

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This commit is contained in:
clubby789 2023-01-21 22:09:56 +00:00
parent 71f6675de1
commit 903ca873f7
6 changed files with 119 additions and 2 deletions
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65
compiler/rustc_infer/src/infer/error_reporting/mod.rs
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@ -64,6 +64,7 @@ use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString};
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit::Visitor;
use rustc_hir::lang_items::LangItem;
use rustc_hir::Node;
use rustc_middle::dep_graph::DepContext;
@ -1975,6 +1976,70 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
(ty::Bool, ty::Tuple(list)) => if list.len() == 0 {
self.suggest_let_for_letchains(&mut err, &trace.cause, span);
}
(ty::Array(_, _), ty::Array(_, _)) => 'block: {
let hir = self.tcx.hir();
let TypeError::FixedArraySize(sz) = terr else {
break 'block;
};
let tykind = match hir.find_by_def_id(trace.cause.body_id) {
Some(hir::Node::Item(hir::Item {
kind: hir::ItemKind::Fn(_, _, body_id),
..
})) => {
let body = hir.body(*body_id);
struct LetVisitor<'v> {
span: Span,
result: Option<&'v hir::Ty<'v>>,
}
impl<'v> Visitor<'v> for LetVisitor<'v> {
fn visit_stmt(&mut self, s: &'v hir::Stmt<'v>) {
if self.result.is_some() {
return;
}
// Find a local statement where the initializer has
// the same span as the error and the type is specified.
if let hir::Stmt {
kind: hir::StmtKind::Local(hir::Local {
init: Some(hir::Expr {
span: init_span,
..
}),
ty: Some(array_ty),
..
}),
..
} = s
&& init_span == &self.span {
self.result = Some(*array_ty);
}
}
}
let mut visitor = LetVisitor {span, result: None};
visitor.visit_body(body);
visitor.result.map(|r| &r.peel_refs().kind)
}
Some(hir::Node::Item(hir::Item {
kind: hir::ItemKind::Const(ty, _),
..
})) => {
Some(&ty.peel_refs().kind)
}
_ => None
};
if let Some(tykind) = tykind
&& let hir::TyKind::Array(_, length) = tykind
&& let hir::ArrayLen::Body(hir::AnonConst { hir_id, .. }) = length
&& let Some(span) = self.tcx.hir().opt_span(*hir_id)
{
err.span_suggestion(
span,
"consider specifying the actual array length",
sz.found,
Applicability::MaybeIncorrect,
);
}
}
_ => {}
}
}