Struct TransferFunction 

struct TransferFunction<'mir, 'tcx, Q> {
    ccx: &'mir ConstCx<'mir, 'tcx>,
    state: &'mir mut State,
    _qualif: PhantomData<Q>,
}

A Visitor that propagates qualifs between locals. This defines the transfer function of FlowSensitiveAnalysis.

To account for indirect assignments, data flow conservatively assumes that local becomes qualified immediately after it is borrowed or its address escapes. The borrow must allow for mutation, which includes shared borrows of places with interior mutability. The type of borrowed place must contain the qualif.

Fields

ccx: &'mir ConstCx<'mir, 'tcx>

state: &'mir mut State

_qualif: PhantomData<Q>

Implementations

impl<'mir, 'tcx, Q> TransferFunction<'mir, 'tcx, Q>

where Q: Qualif,

fn new(ccx: &'mir ConstCx<'mir, 'tcx>, state: &'mir mut State) -> Self

fn initialize_state(&mut self)

fn assign_qualif_direct(&mut self, place: &Place<'tcx>, value: bool)

fn apply_call_return_effect( &mut self, _block: BasicBlock, return_places: CallReturnPlaces<'_, 'tcx>, )

fn address_of_allows_mutation(&self) -> bool

fn ref_allows_mutation(&self, kind: BorrowKind, place: Place<'tcx>) -> bool

fn shared_borrow_allows_mutation(&self, place: Place<'tcx>) -> bool

& only allow mutation if the borrowed place is !Freeze.

This assumes that const-eval will abort when one creates a shared reference to a struct field whose type is Freeze, then uses pointer arithmetic to derive a pointer to a different field of that same struct whose type is !Freeze and mutates that. It is not enough for that to be UB (which we are pretty sure it is, and it would be a breaking change to make it non-UB as we’d then have to make const checking more conservative here), const-eval also has to reliably detect that UB to ensure we never invoke a destructor after such a mutation occurs!

Trait Implementations

impl<'tcx, Q> Visitor<'tcx> for TransferFunction<'_, 'tcx, Q>

where Q: Qualif,

fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location)

fn visit_assign( &mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location, )

fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location)

fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location)

fn visit_terminator( &mut self, terminator: &Terminator<'tcx>, location: Location, )

fn visit_body(&mut self, body: &Body<'tcx>)

fn visit_basic_block_data( &mut self, block: BasicBlock, data: &BasicBlockData<'tcx>, )

fn visit_source_scope_data(&mut self, scope_data: &SourceScopeData<'tcx>)

fn visit_statement_debuginfo( &mut self, stmt_debuginfo: &StmtDebugInfo<'tcx>, location: Location, )

fn visit_assert_message( &mut self, msg: &AssertKind<Operand<'tcx>>, location: Location, )

fn visit_ascribe_user_ty( &mut self, place: &Place<'tcx>, variance: Variance, user_ty: &UserTypeProjection, location: Location, )

fn visit_coverage(&mut self, kind: &CoverageKind, location: Location)

fn visit_place( &mut self, place: &Place<'tcx>, context: PlaceContext, location: Location, )

fn visit_projection( &mut self, place_ref: PlaceRef<'tcx>, context: PlaceContext, location: Location, )

fn visit_projection_elem( &mut self, place_ref: PlaceRef<'tcx>, elem: ProjectionElem<Local, Ty<'tcx>>, context: PlaceContext, location: Location, )

fn super_place( &mut self, place: &Place<'tcx>, context: PlaceContext, location: Location, )

fn super_projection( &mut self, place_ref: PlaceRef<'tcx>, context: PlaceContext, location: Location, )

fn super_projection_elem( &mut self, _place_ref: PlaceRef<'tcx>, elem: ProjectionElem<Local, Ty<'tcx>>, context: PlaceContext, location: Location, )

fn visit_const_operand( &mut self, constant: &ConstOperand<'tcx>, location: Location, )

This is called for every constant in the MIR body and every required_consts (i.e., including consts that have been dead-code-eliminated).

fn visit_ty_const(&mut self, ct: Const<TyCtxt<'tcx>>, location: Location)

fn visit_span(&mut self, span: Span)

fn visit_source_info(&mut self, source_info: &SourceInfo)

fn visit_ty(&mut self, ty: Ty<'tcx>, _: TyContext)

fn visit_user_type_projection(&mut self, ty: &UserTypeProjection)

fn visit_user_type_annotation( &mut self, index: UserTypeAnnotationIndex, ty: &CanonicalUserTypeAnnotation<'tcx>, )

fn visit_region(&mut self, region: Region<TyCtxt<'tcx>>, _: Location)

fn visit_args( &mut self, args: &&'tcx RawList<(), GenericArg<'tcx>>, _: Location, )

fn visit_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>)

fn visit_var_debug_info(&mut self, var_debug_info: &VarDebugInfo<'tcx>)

fn visit_local( &mut self, local: Local, context: PlaceContext, location: Location, )

fn visit_source_scope(&mut self, scope: SourceScope)

fn super_body(&mut self, body: &Body<'tcx>)

fn super_basic_block_data( &mut self, block: BasicBlock, data: &BasicBlockData<'tcx>, )

fn super_source_scope_data(&mut self, scope_data: &SourceScopeData<'tcx>)

fn super_statement_debuginfo( &mut self, stmt_debuginfo: &StmtDebugInfo<'tcx>, location: Location, )

fn super_statement(&mut self, statement: &Statement<'tcx>, location: Location)

fn super_assign( &mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location, )

fn super_terminator( &mut self, terminator: &Terminator<'tcx>, location: Location, )

fn super_assert_message( &mut self, msg: &AssertKind<Operand<'tcx>>, location: Location, )

fn super_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location)

fn super_operand(&mut self, operand: &Operand<'tcx>, location: Location)

fn super_ascribe_user_ty( &mut self, place: &Place<'tcx>, variance: Variance, user_ty: &UserTypeProjection, location: Location, )

fn super_coverage(&mut self, _kind: &CoverageKind, _location: Location)

fn super_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>)

fn super_local( &mut self, _local: Local, _context: PlaceContext, _location: Location, )

fn super_var_debug_info(&mut self, var_debug_info: &VarDebugInfo<'tcx>)

fn super_source_scope(&mut self, _scope: SourceScope)

fn super_const_operand( &mut self, constant: &ConstOperand<'tcx>, location: Location, )

fn super_ty_const(&mut self, _ct: Const<TyCtxt<'tcx>>, _location: Location)

fn super_span(&mut self, _span: Span)

fn super_source_info(&mut self, source_info: &SourceInfo)

fn super_user_type_projection(&mut self, _ty: &UserTypeProjection)

fn super_user_type_annotation( &mut self, _index: UserTypeAnnotationIndex, ty: &CanonicalUserTypeAnnotation<'tcx>, )

fn super_ty(&mut self, _ty: Ty<'tcx>)

fn super_region(&mut self, _region: Region<TyCtxt<'tcx>>)

fn super_args(&mut self, _args: &&'tcx RawList<(), GenericArg<'tcx>>)

fn visit_location(&mut self, body: &Body<'tcx>, location: Location)

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 16 bytes