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Move logic to its own method
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+63
-73
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1 file changed

+63
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‎src/librustc_typeck/check/coercion.rs‎

Lines changed: 63 additions & 73 deletions
Original file line numberDiff line numberDiff line change
@@ -1208,83 +1208,20 @@ impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E>
12081208
db.span_label(cause.span, "return type is not `()`");
12091209
}
12101210
ObligationCauseCode::BlockTailExpression(blk_id) => {
1211-
db = fcx.report_mismatched_types(cause, expected, found, err);
1212-
1213-
let expr = expression.unwrap_or_else(|| {
1214-
span_bug!(cause.span,
1215-
"supposed to be part of a block tail expression, but the \
1216-
expression is empty");
1217-
});
1218-
let pointing_at_return_type = fcx.suggest_mismatched_types_on_tail(
1219-
&mut db,
1220-
expr,
1211+
let parent_id = fcx.tcx.hir().get_parent_node(blk_id);
1212+
db = self.report_return_mismatched_types(
1213+
cause,
12211214
expected,
12221215
found,
1223-
cause.span,
1224-
blk_id,
1216+
err,
1217+
fcx,
1218+
parent_id,
1219+
expression.map(|expr| (expr, blk_id)),
12251220
);
1226-
// FIXME: replace with navigating up the chain until hitting an fn or
1227-
// bailing if no "pass-through" Node is found, in order to provide a
1228-
// suggestion when encountering something like:
1229-
// ```
1230-
// fn foo(a: bool) -> impl Debug {
1231-
// if a {
1232-
// bar()?;
1233-
// }
1234-
// {
1235-
// let x = unsafe { bar() };
1236-
// x
1237-
// }
1238-
// }
1239-
// ```
1240-
//
1241-
// Verify that this is a tail expression of a function, otherwise the
1242-
// label pointing out the cause for the type coercion will be wrong
1243-
// as prior return coercions would not be relevant (#57664).
1244-
let parent_id = fcx.tcx.hir().get_parent_node(blk_id);
1245-
let parent = fcx.tcx.hir().get(fcx.tcx.hir().get_parent_node(parent_id));
1246-
if let (Some((fn_decl, _, _)), false) = (
1247-
fcx.get_node_fn_decl(parent),
1248-
pointing_at_return_type,
1249-
) {
1250-
if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() {
1251-
db.span_label(
1252-
fn_decl.output.span(),
1253-
"expected because this return type...",
1254-
);
1255-
db.span_label(*sp, format!(
1256-
"...is found to be `{}` here",
1257-
fcx.resolve_type_vars_with_obligations(expected),
1258-
));
1259-
}
1260-
}
12611221
}
1262-
ObligationCauseCode::ReturnType(_id) => {
1263-
db = fcx.report_mismatched_types(cause, expected, found, err);
1264-
let _id = fcx.tcx.hir().get_parent_node(_id);
1265-
let mut pointing_at_return_type = false;
1266-
let mut return_sp = None;
1267-
if let Some((fn_decl, can_suggest)) = fcx.get_fn_decl(_id) {
1268-
pointing_at_return_type = fcx.suggest_missing_return_type(
1269-
&mut db, &fn_decl, expected, found, can_suggest);
1270-
if !pointing_at_return_type {
1271-
return_sp = Some(fn_decl.output.span()); // `impl Trait` return type
1272-
}
1273-
}
1274-
if let (Some(sp), false) = (
1275-
fcx.ret_coercion_span.borrow().as_ref(),
1276-
pointing_at_return_type,
1277-
) {
1278-
if let Some(return_sp) = return_sp {
1279-
db.span_label(return_sp, "expected because this return type...");
1280-
db.span_label( *sp, format!(
1281-
"...is found to be `{}` here",
1282-
fcx.resolve_type_vars_with_obligations(expected),
1283-
));
1284-
} else if !sp.overlaps(cause.span) {
1285-
db.span_label(*sp, "expected because of this statement");
1286-
}
1287-
}
1222+
ObligationCauseCode::ReturnType(id) => {
1223+
db = self.report_return_mismatched_types(
1224+
cause, expected, found, err, fcx, id, None);
12881225
}
12891226
_ => {
12901227
db = fcx.report_mismatched_types(cause, expected, found, err);
@@ -1302,6 +1239,59 @@ impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E>
13021239
}
13031240
}
13041241

1242+
fn report_return_mismatched_types<'a>(
1243+
&self,
1244+
cause: &ObligationCause<'tcx>,
1245+
expected: Ty<'tcx>,
1246+
found: Ty<'tcx>,
1247+
err: TypeError<'tcx>,
1248+
fcx: &FnCtxt<'a, 'gcx, 'tcx>,
1249+
id: syntax::ast::NodeId,
1250+
expression: Option<(&'gcx hir::Expr, syntax::ast::NodeId)>,
1251+
) -> DiagnosticBuilder<'a> {
1252+
let mut db = fcx.report_mismatched_types(cause, expected, found, err);
1253+
1254+
let mut pointing_at_return_type = false;
1255+
let mut return_sp = None;
1256+
1257+
// Verify that this is a tail expression of a function, otherwise the
1258+
// label pointing out the cause for the type coercion will be wrong
1259+
// as prior return coercions would not be relevant (#57664).
1260+
let parent_id = fcx.tcx.hir().get_parent_node(id);
1261+
let fn_decl = if let Some((expr, blk_id)) = expression {
1262+
pointing_at_return_type = fcx.suggest_mismatched_types_on_tail(
1263+
&mut db,
1264+
expr,
1265+
expected,
1266+
found,
1267+
cause.span,
1268+
blk_id,
1269+
);
1270+
let parent = fcx.tcx.hir().get(parent_id);
1271+
fcx.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main))
1272+
} else {
1273+
fcx.get_fn_decl(parent_id)
1274+
};
1275+
1276+
if let (Some((fn_decl, can_suggest)), _) = (fn_decl, pointing_at_return_type) {
1277+
if expression.is_none() {
1278+
pointing_at_return_type |= fcx.suggest_missing_return_type(
1279+
&mut db, &fn_decl, expected, found, can_suggest);
1280+
}
1281+
if !pointing_at_return_type {
1282+
return_sp = Some(fn_decl.output.span()); // `impl Trait` return type
1283+
}
1284+
}
1285+
if let (Some(sp), Some(return_sp)) = (fcx.ret_coercion_span.borrow().as_ref(), return_sp) {
1286+
db.span_label(return_sp, "expected because this return type...");
1287+
db.span_label( *sp, format!(
1288+
"...is found to be `{}` here",
1289+
fcx.resolve_type_vars_with_obligations(expected),
1290+
));
1291+
}
1292+
db
1293+
}
1294+
13051295
pub fn complete<'a>(self, fcx: &FnCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
13061296
if let Some(final_ty) = self.final_ty {
13071297
final_ty

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