diff options
| -rw-r--r-- | compiler/rustc_feature/src/builtin_attrs.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/fallback.rs | 18 | ||||
| -rw-r--r-- | compiler/rustc_span/src/symbol.rs | 1 |
3 files changed, 18 insertions, 3 deletions
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs index a5f8b0b270f..e5a29f3a846 100644 --- a/compiler/rustc_feature/src/builtin_attrs.rs +++ b/compiler/rustc_feature/src/builtin_attrs.rs @@ -581,7 +581,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ ), rustc_attr!( - rustc_never_type_mode, Normal, template!(NameValueStr: "fallback_to_unit|fallback_to_niko|no_fallback"), ErrorFollowing, + rustc_never_type_mode, Normal, template!(NameValueStr: "fallback_to_unit|fallback_to_niko|fallback_to_never|no_fallback"), ErrorFollowing, @only_local: true, "`rustc_never_type_fallback` is used to experiment with never type fallback and work on \ never type stabilization, and will never be stable" diff --git a/compiler/rustc_hir_typeck/src/fallback.rs b/compiler/rustc_hir_typeck/src/fallback.rs index 5206e79177b..c16e941d4c5 100644 --- a/compiler/rustc_hir_typeck/src/fallback.rs +++ b/compiler/rustc_hir_typeck/src/fallback.rs @@ -14,6 +14,9 @@ enum DivergingFallbackBehavior { FallbackToUnit, /// Sometimes fallback to `!`, but mainly fallback to `()` so that most of the crates are not broken. FallbackToNiko, + /// Always fallback to `!` (which should be equivalent to never falling back + not making + /// never-to-any coercions unless necessary) + FallbackToNever, /// Don't fallback at all NoFallback, } @@ -107,9 +110,10 @@ impl<'tcx> FnCtxt<'_, 'tcx> { match mode { sym::fallback_to_unit => DivergingFallbackBehavior::FallbackToUnit, sym::fallback_to_niko => DivergingFallbackBehavior::FallbackToNiko, + sym::fallback_to_never => DivergingFallbackBehavior::FallbackToNever, sym::no_fallback => DivergingFallbackBehavior::NoFallback, _ => { - self.tcx.dcx().span_err(span, format!("unknown never type mode: `{mode}` (supported: `fallback_to_unit`, `fallback_to_niko`, and `no_fallback`)")); + self.tcx.dcx().span_err(span, format!("unknown never type mode: `{mode}` (supported: `fallback_to_unit`, `fallback_to_niko`, `fallback_to_never` and `no_fallback`)")); DivergingFallbackBehavior::FallbackToUnit } @@ -426,8 +430,18 @@ impl<'tcx> FnCtxt<'_, 'tcx> { diverging_fallback.insert(diverging_ty, self.tcx.types.never); } } + FallbackToNever => { + debug!( + "fallback to ! - `rustc_never_type_mode = \"fallback_to_never\")`: {:?}", + diverging_vid + ); + diverging_fallback.insert(diverging_ty, self.tcx.types.never); + } NoFallback => { - debug!("no fallback - `rustc_never_type_mode = "no_fallback"`: {:?}", diverging_vid); + debug!( + "no fallback - `rustc_never_type_mode = \"no_fallback\"`: {:?}", + diverging_vid + ); } } } diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 0df5e7873c2..e43c9533382 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -815,6 +815,7 @@ symbols! { fadd_algebraic, fadd_fast, fake_variadic, + fallback_to_never, fallback_to_niko, fallback_to_unit, fdiv_algebraic, |