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fix: Crash on MIR lowering for out-of-range tuple access
Projection assumes the tuple is big enough for the field access, so
return a MIR lowering error earlier if the tuple isn't valid.
AI disclosure: Some Fable 5 and GPT 5.5 usage.
| -rw-r--r-- | crates/hir-ty/src/mir/lower.rs | 7 | ||||
| -rw-r--r-- | crates/hir-ty/src/mir/lower/tests.rs | 13 |
2 files changed, 18 insertions, 2 deletions
diff --git a/crates/hir-ty/src/mir/lower.rs b/crates/hir-ty/src/mir/lower.rs index d1277762eb..ab7e6df3f5 100644 --- a/crates/hir-ty/src/mir/lower.rs +++ b/crates/hir-ty/src/mir/lower.rs @@ -1404,11 +1404,14 @@ impl<'a, 'db> MirLowerCtx<'a, 'db> { expr_id: ExprId, ) -> Result<'db, ()> { if let Expr::Field { expr, name } = &self.store[expr_id] { - if let TyKind::Tuple(..) = self.expr_ty_after_adjustments(*expr).kind() { + if let TyKind::Tuple(tys) = self.expr_ty_after_adjustments(*expr).kind() { let index = name.as_tuple_index().ok_or(MirLowerError::TypeError("named field on tuple"))? as u32; - *place = place.project(ProjectionElem::Field(FieldIndex(index))) + if tys.get(index as usize).is_none() { + return Err(MirLowerError::TypeError("tuple field index out of range")); + } + *place = place.project(ProjectionElem::Field(FieldIndex(index))); } else { let field = self .infer diff --git a/crates/hir-ty/src/mir/lower/tests.rs b/crates/hir-ty/src/mir/lower/tests.rs index 8e10284cc1..bf13b4c46e 100644 --- a/crates/hir-ty/src/mir/lower/tests.rs +++ b/crates/hir-ty/src/mir/lower/tests.rs @@ -108,3 +108,16 @@ pub struct AssocTy { "#, ); } + +#[test] +fn borrowck_tuple_field_projection_recovery_does_not_panic() { + check_borrowck( + r#" +//- minicore: sized +fn tuple_field() { + let t = (1,); + let x = t.1; +} + "#, + ); +} |