Unnamed repository; edit this file 'description' to name the repository.
Fix `unused-mut` false positive for `Box`
| -rw-r--r-- | crates/hir-ty/src/mir/borrowck.rs | 43 | ||||
| -rw-r--r-- | crates/ide-diagnostics/src/handlers/mutability_errors.rs | 52 |
2 files changed, 83 insertions, 12 deletions
diff --git a/crates/hir-ty/src/mir/borrowck.rs b/crates/hir-ty/src/mir/borrowck.rs index 66af6658e8..a0ea1cc5ef 100644 --- a/crates/hir-ty/src/mir/borrowck.rs +++ b/crates/hir-ty/src/mir/borrowck.rs @@ -78,7 +78,7 @@ pub fn borrowck_query( .map(|body| { let body = body?; Ok(BorrowckResult { - mutability_of_locals: mutability_of_locals(&body), + mutability_of_locals: mutability_of_locals(db, &body), moved_out_of_ref: moved_out_of_ref(db, &body), mir_body: body, }) @@ -186,10 +186,7 @@ fn moved_out_of_ref(db: &dyn HirDatabase, body: &MirBody) -> Vec<MovedOutOfRef> result } -fn is_place_direct(lvalue: &Place) -> bool { - !lvalue.projection.iter().any(|x| *x == ProjectionElem::Deref) -} - +#[derive(Debug, Clone, Copy, PartialEq, Eq)] enum ProjectionCase { /// Projection is a local Direct, @@ -199,12 +196,14 @@ enum ProjectionCase { Indirect, } -fn place_case(lvalue: &Place) -> ProjectionCase { +fn place_case(db: &dyn HirDatabase, body: &MirBody, lvalue: &Place) -> ProjectionCase { let mut is_part_of = false; - for proj in lvalue.projection.iter().rev() { + let mut ty = body.locals[lvalue.local].ty.clone(); + for proj in lvalue.projection.iter() { match proj { - ProjectionElem::Deref => return ProjectionCase::Indirect, // It's indirect - ProjectionElem::ConstantIndex { .. } + ProjectionElem::Deref if ty.as_adt().is_none() => return ProjectionCase::Indirect, // It's indirect in case of reference and raw + ProjectionElem::Deref // It's direct in case of `Box<T>` + | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } | ProjectionElem::Field(_) | ProjectionElem::TupleOrClosureField(_) @@ -213,6 +212,23 @@ fn place_case(lvalue: &Place) -> ProjectionCase { } ProjectionElem::OpaqueCast(_) => (), } + ty = proj.projected_ty( + ty, + db, + |c, subst, f| { + let (def, _) = db.lookup_intern_closure(c.into()); + let infer = db.infer(def); + let (captures, _) = infer.closure_info(&c); + let parent_subst = ClosureSubst(subst).parent_subst(); + captures + .get(f) + .expect("broken closure field") + .ty + .clone() + .substitute(Interner, parent_subst) + }, + body.owner.module(db.upcast()).krate(), + ); } if is_part_of { ProjectionCase::DirectPart @@ -300,7 +316,10 @@ fn ever_initialized_map(body: &MirBody) -> ArenaMap<BasicBlockId, ArenaMap<Local result } -fn mutability_of_locals(body: &MirBody) -> ArenaMap<LocalId, MutabilityReason> { +fn mutability_of_locals( + db: &dyn HirDatabase, + body: &MirBody, +) -> ArenaMap<LocalId, MutabilityReason> { let mut result: ArenaMap<LocalId, MutabilityReason> = body.locals.iter().map(|x| (x.0, MutabilityReason::Not)).collect(); let mut push_mut_span = |local, span| match &mut result[local] { @@ -313,7 +332,7 @@ fn mutability_of_locals(body: &MirBody) -> ArenaMap<LocalId, MutabilityReason> { for statement in &block.statements { match &statement.kind { StatementKind::Assign(place, value) => { - match place_case(place) { + match place_case(db, body, place) { ProjectionCase::Direct => { if ever_init_map.get(place.local).copied().unwrap_or_default() { push_mut_span(place.local, statement.span); @@ -328,7 +347,7 @@ fn mutability_of_locals(body: &MirBody) -> ArenaMap<LocalId, MutabilityReason> { ProjectionCase::Indirect => (), } if let Rvalue::Ref(BorrowKind::Mut { .. }, p) = value { - if is_place_direct(p) { + if place_case(db, body, p) != ProjectionCase::Indirect { push_mut_span(p.local, statement.span); } } diff --git a/crates/ide-diagnostics/src/handlers/mutability_errors.rs b/crates/ide-diagnostics/src/handlers/mutability_errors.rs index b95c8c573b..8795afc2d9 100644 --- a/crates/ide-diagnostics/src/handlers/mutability_errors.rs +++ b/crates/ide-diagnostics/src/handlers/mutability_errors.rs @@ -994,6 +994,58 @@ fn f() { } #[test] + fn boxes() { + check_diagnostics( + r#" +//- minicore: coerce_unsized, deref_mut, slice +use core::ops::{Deref, DerefMut}; +use core::{marker::Unsize, ops::CoerceUnsized}; + +#[lang = "owned_box"] +pub struct Box<T: ?Sized> { + inner: *mut T, +} +impl<T> Box<T> { + fn new(t: T) -> Self { + #[rustc_box] + Box::new(t) + } +} + +impl<T: ?Sized> Deref for Box<T> { + type Target = T; + + fn deref(&self) -> &T { + &**self + } +} + +impl<T: ?Sized> DerefMut for Box<T> { + fn deref_mut(&mut self) -> &mut T { + &mut **self + } +} + +fn f() { + let x = Box::new(5); + x = Box::new(7); + //^^^^^^^^^^^^^^^ 💡 error: cannot mutate immutable variable `x` + let x = Box::new(5); + *x = 7; + //^^^^^^ 💡 error: cannot mutate immutable variable `x` + let mut y = Box::new(5); + //^^^^^ 💡 weak: variable does not need to be mutable + *x = *y; + //^^^^^^^ 💡 error: cannot mutate immutable variable `x` + let x = Box::new(5); + let closure = || *x = 2; + //^ 💡 error: cannot mutate immutable variable `x` +} +"#, + ); + } + + #[test] fn allow_unused_mut_for_identifiers_starting_with_underline() { check_diagnostics( r#" |