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Rollup merge of #87061 - FabianWolff:issue-87051, r=oli-obk

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Do not suggest adding a semicolon after `?`

Fixes #87051. I have only modified `report_return_mismatched_types()`, i.e. my changes only affect suggestions to add `;` for return type mismatches, but this never makes sense after `?`, because the function cannot return `()` if `?` is used (it has to return a `Result` or an `Option`), and a semicolon won't help if the expected and actual `Err` types differ, even if the expected one is `()`.
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Yuki Okushi 2021-07-12 04:32:05 +09:00 • committed by GitHub
commit 5fcefb1d61
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3 changed files with 67 additions and 3 deletions
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10
compiler/rustc_typeck/src/check/coercion.rs
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@ -1456,11 +1456,15 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
expected.is_unit(),
pointing_at_return_type,
) {
// If the block is from an external macro, then do not suggest
// adding a semicolon, because there's nowhere to put it.
// See issue #81943.
// If the block is from an external macro or try (`?`) desugaring, then
// do not suggest adding a semicolon, because there's nowhere to put it.
// See issues #81943 and #87051.
if cond_expr.span.desugaring_kind().is_none()
&& !in_external_macro(fcx.tcx.sess, cond_expr.span)
&& !matches!(
cond_expr.kind,
hir::ExprKind::Match(.., hir::MatchSource::TryDesugar)
)
{
err.span_label(cond_expr.span, "expected this to be `()`");
if expr.can_have_side_effects() {