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Rollup merge of rust-lang#61241 - spastorino:check-place-iterative, r…
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…=oli-obk

Check place iterative

r? @oli-obk
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@Centril
Centril committed May 28, 2019
2 parents a449bc3 + fb4b62b commit c33b349
Showing 1 changed file with 36 additions and 39 deletions.
75 changes: 36 additions & 39 deletions src/librustc_mir/transform/qualify_min_const_fn.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,10 +136,10 @@ fn check_rvalue(
) -> McfResult {
match rvalue {
Rvalue::Repeat(operand, _) | Rvalue::Use(operand) => {
check_operand(tcx, mir, operand, span)
check_operand(operand, span)
}
Rvalue::Len(place) | Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) => {
check_place(tcx, mir, place, span)
check_place(place, span)
}
Rvalue::Cast(CastKind::Misc, operand, cast_ty) => {
use rustc::ty::cast::CastTy;
Expand All @@ -153,11 +153,11 @@ fn check_rvalue(
(CastTy::RPtr(_), CastTy::Float) => bug!(),
(CastTy::RPtr(_), CastTy::Int(_)) => bug!(),
(CastTy::Ptr(_), CastTy::RPtr(_)) => bug!(),
_ => check_operand(tcx, mir, operand, span),
_ => check_operand(operand, span),
}
}
Rvalue::Cast(CastKind::Pointer(PointerCast::MutToConstPointer), operand, _) => {
check_operand(tcx, mir, operand, span)
check_operand(operand, span)
}
Rvalue::Cast(CastKind::Pointer(PointerCast::UnsafeFnPointer), _, _) |
Rvalue::Cast(CastKind::Pointer(PointerCast::ClosureFnPointer(_)), _, _) |
Expand All @@ -171,8 +171,8 @@ fn check_rvalue(
)),
// binops are fine on integers
Rvalue::BinaryOp(_, lhs, rhs) | Rvalue::CheckedBinaryOp(_, lhs, rhs) => {
check_operand(tcx, mir, lhs, span)?;
check_operand(tcx, mir, rhs, span)?;
check_operand(lhs, span)?;
check_operand(rhs, span)?;
let ty = lhs.ty(mir, tcx);
if ty.is_integral() || ty.is_bool() || ty.is_char() {
Ok(())
Expand All @@ -191,7 +191,7 @@ fn check_rvalue(
Rvalue::UnaryOp(_, operand) => {
let ty = operand.ty(mir, tcx);
if ty.is_integral() || ty.is_bool() {
check_operand(tcx, mir, operand, span)
check_operand(operand, span)
} else {
Err((
span,
Expand All @@ -201,7 +201,7 @@ fn check_rvalue(
}
Rvalue::Aggregate(_, operands) => {
for operand in operands {
check_operand(tcx, mir, operand, span)?;
check_operand(operand, span)?;
}
Ok(())
}
Expand All @@ -216,11 +216,11 @@ fn check_statement(
let span = statement.source_info.span;
match &statement.kind {
StatementKind::Assign(place, rval) => {
check_place(tcx, mir, place, span)?;
check_place(place, span)?;
check_rvalue(tcx, mir, rval, span)
}

StatementKind::FakeRead(_, place) => check_place(tcx, mir, place, span),
StatementKind::FakeRead(_, place) => check_place(place, span),

// just an assignment
StatementKind::SetDiscriminant { .. } => Ok(()),
Expand All @@ -239,43 +239,40 @@ fn check_statement(
}

fn check_operand(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
mir: &'a Mir<'tcx>,
operand: &Operand<'tcx>,
span: Span,
) -> McfResult {
match operand {
Operand::Move(place) | Operand::Copy(place) => {
check_place(tcx, mir, place, span)
check_place(place, span)
}
Operand::Constant(_) => Ok(()),
}
}

fn check_place(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
mir: &'a Mir<'tcx>,
place: &Place<'tcx>,
span: Span,
) -> McfResult {
match place {
Place::Base(PlaceBase::Local(_)) => Ok(()),
// promoteds are always fine, they are essentially constants
Place::Base(PlaceBase::Static(box Static { kind: StaticKind::Promoted(_), .. })) => Ok(()),
Place::Base(PlaceBase::Static(box Static { kind: StaticKind::Static(_), .. })) =>
Err((span, "cannot access `static` items in const fn".into())),
Place::Projection(proj) => {
fn check_place(place: &Place<'tcx>, span: Span) -> McfResult {
place.iterate(|place_base, place_projection| {
for proj in place_projection {
match proj.elem {
| ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. }
| ProjectionElem::Deref | ProjectionElem::Field(..) | ProjectionElem::Index(_) => {
check_place(tcx, mir, &proj.base, span)
}
| ProjectionElem::Downcast(..) => {
Err((span, "`match` or `if let` in `const fn` is unstable".into()))
ProjectionElem::Downcast(..) => {
return Err((span, "`match` or `if let` in `const fn` is unstable".into()));
}
ProjectionElem::ConstantIndex { .. }
| ProjectionElem::Subslice { .. }
| ProjectionElem::Deref
| ProjectionElem::Field(..)
| ProjectionElem::Index(_) => {}
}
}
}

match place_base {
PlaceBase::Static(box Static { kind: StaticKind::Static(_), .. }) => {
Err((span, "cannot access `static` items in const fn".into()))
}
PlaceBase::Local(_)
| PlaceBase::Static(box Static { kind: StaticKind::Promoted(_), .. }) => Ok(()),
}
})
}

fn check_terminator(
Expand All @@ -290,11 +287,11 @@ fn check_terminator(
| TerminatorKind::Resume => Ok(()),

TerminatorKind::Drop { location, .. } => {
check_place(tcx, mir, location, span)
check_place(location, span)
}
TerminatorKind::DropAndReplace { location, value, .. } => {
check_place(tcx, mir, location, span)?;
check_operand(tcx, mir, value, span)
check_place(location, span)?;
check_operand(value, span)
},

TerminatorKind::FalseEdges { .. } | TerminatorKind::SwitchInt { .. } => Err((
Expand Down Expand Up @@ -346,10 +343,10 @@ fn check_terminator(
)),
}

check_operand(tcx, mir, func, span)?;
check_operand(func, span)?;

for arg in args {
check_operand(tcx, mir, arg, span)?;
check_operand(arg, span)?;
}
Ok(())
} else {
Expand All @@ -363,7 +360,7 @@ fn check_terminator(
msg: _,
target: _,
cleanup: _,
} => check_operand(tcx, mir, cond, span),
} => check_operand(cond, span),

TerminatorKind::FalseUnwind { .. } => {
Err((span, "loops are not allowed in const fn".into()))
Expand Down

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