diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs index 21d0a7869d68e..8ab9f77d0ea78 100644 --- a/compiler/rustc_typeck/src/check/coercion.rs +++ b/compiler/rustc_typeck/src/check/coercion.rs @@ -1479,6 +1479,10 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { } } Err(coercion_error) => { + // Mark that we've failed to coerce the types here to suppress + // any superfluous errors we might encounter while trying to + // emit or provide suggestions on how to fix the initial error. + fcx.set_tainted_by_errors(); let (expected, found) = if label_expression_as_expected { // In the case where this is a "forced unit", like // `break`, we want to call the `()` "expected" diff --git a/src/test/ui/typeck/issue-100246.rs b/src/test/ui/typeck/issue-100246.rs new file mode 100644 index 0000000000000..8f0b34bab0c87 --- /dev/null +++ b/src/test/ui/typeck/issue-100246.rs @@ -0,0 +1,30 @@ +#![recursion_limit = "5"] // To reduce noise + +//expect incompatible type error when ambiguous traits are in scope +//and not an overflow error on the span in the main function. + +struct Ratio(T); + +pub trait Pow { + fn pow(self) -> Self; +} + +impl<'a, T> Pow for &'a Ratio +where + &'a T: Pow, +{ + fn pow(self) -> Self { + self + } +} + +fn downcast<'a, W: ?Sized>() -> std::io::Result<&'a W> { + todo!() +} + +struct Other; + +fn main() -> std::io::Result<()> { + let other: Other = downcast()?;//~ERROR 28:24: 28:35: `?` operator has incompatible types + Ok(()) +} diff --git a/src/test/ui/typeck/issue-100246.stderr b/src/test/ui/typeck/issue-100246.stderr new file mode 100644 index 0000000000000..8b77de94e89f8 --- /dev/null +++ b/src/test/ui/typeck/issue-100246.stderr @@ -0,0 +1,13 @@ +error[E0308]: `?` operator has incompatible types + --> $DIR/issue-100246.rs:28:24 + | +LL | let other: Other = downcast()?; + | ^^^^^^^^^^^ expected struct `Other`, found reference + | + = note: `?` operator cannot convert from `&_` to `Other` + = note: expected struct `Other` + found reference `&_` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0308`.