bjoernager/rust
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Suggest a trailing comma if a 1-tuple is expected

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This commit is contained in:
Fabian Wolff 2021-06-07 23:16:03 +02:00
parent e4a6032706
commit 6206247335
3 changed files with 108 additions and 1 deletions
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29
compiler/rustc_infer/src/infer/error_reporting/mod.rs
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@ -64,6 +64,7 @@ use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{Item, ItemKind, Node};
use rustc_middle::dep_graph::DepContext;
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::{
self,
@ -1965,7 +1966,33 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
struct_span_err!(self.tcx.sess, span, E0580, "{}", failure_str)
}
FailureCode::Error0308(failure_str) => {
struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str)
let mut err = struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str);
if let ValuePairs::Types(ty::error::ExpectedFound { expected, found }) =
trace.values
{
// If a tuple of length one was expected and the found expression has
// parentheses around it, perhaps the user meant to write `(expr,)` to
// build a tuple (issue #86100)
match (expected.kind(), found.kind()) {
(ty::Tuple(_), ty::Tuple(_)) => {}
(ty::Tuple(_), _) if expected.tuple_fields().count() == 1 => {
if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span) {
if let Some(code) =
code.strip_prefix('(').and_then(|s| s.strip_suffix(')'))
{
err.span_suggestion(
span,
"use a trailing comma to create a tuple with one element",
format!("({},)", code),
Applicability::MaybeIncorrect,
);
}
}
}
_ => {}
}
}
err
}
FailureCode::Error0644(failure_str) => {
struct_span_err!(self.tcx.sess, span, E0644, "{}", failure_str)