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Rewrite the improper_ctypes lint.
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Makes the lint a bit more accurate, and improves the quality of the diagnostic
messages by explicitly returning an error message.

The new lint is also a little more aggressive: specifically, it now
rejects tuples, and it recurses into function pointers.
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@eefriedman
eefriedman committed Jul 24, 2015
1 parent d4d4206 commit 6fa17b4
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Showing 14 changed files with 345 additions and 177 deletions.
136 changes: 12 additions & 124 deletions src/librustc/middle/ty.rs
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Expand Up @@ -3967,7 +3967,6 @@ def_type_content_sets! {
None = 0b0000_0000__0000_0000__0000,

// Things that are interior to the value (first nibble):
InteriorUnsized = 0b0000_0000__0000_0000__0001,
InteriorUnsafe = 0b0000_0000__0000_0000__0010,
InteriorParam = 0b0000_0000__0000_0000__0100,
// InteriorAll = 0b00000000__00000000__1111,
Expand All @@ -3977,18 +3976,9 @@ def_type_content_sets! {
OwnsDtor = 0b0000_0000__0000_0010__0000,
OwnsAll = 0b0000_0000__1111_1111__0000,

// Things that are reachable by the value in any way (fourth nibble):
ReachesBorrowed = 0b0000_0010__0000_0000__0000,
ReachesMutable = 0b0000_1000__0000_0000__0000,
ReachesFfiUnsafe = 0b0010_0000__0000_0000__0000,
ReachesAll = 0b0011_1111__0000_0000__0000,

// Things that mean drop glue is necessary
NeedsDrop = 0b0000_0000__0000_0111__0000,

// Things that prevent values from being considered sized
Nonsized = 0b0000_0000__0000_0000__0001,

// All bits
All = 0b1111_1111__1111_1111__1111
}
Expand All @@ -4007,10 +3997,6 @@ impl TypeContents {
self.intersects(TC::OwnsOwned)
}

pub fn is_sized(&self, _: &ctxt) -> bool {
!self.intersects(TC::Nonsized)
}

pub fn interior_param(&self) -> bool {
self.intersects(TC::InteriorParam)
}
Expand All @@ -4019,29 +4005,13 @@ impl TypeContents {
self.intersects(TC::InteriorUnsafe)
}

pub fn interior_unsized(&self) -> bool {
self.intersects(TC::InteriorUnsized)
}

pub fn needs_drop(&self, _: &ctxt) -> bool {
self.intersects(TC::NeedsDrop)
}

/// Includes only those bits that still apply when indirected through a `Box` pointer
pub fn owned_pointer(&self) -> TypeContents {
TC::OwnsOwned | (
*self & (TC::OwnsAll | TC::ReachesAll))
}

/// Includes only those bits that still apply when indirected through a reference (`&`)
pub fn reference(&self, bits: TypeContents) -> TypeContents {
bits | (
*self & TC::ReachesAll)
}

/// Includes only those bits that still apply when indirected through a raw pointer (`*`)
pub fn unsafe_pointer(&self) -> TypeContents {
*self & TC::ReachesAll
TC::OwnsOwned | (*self & TC::OwnsAll)
}

pub fn union<T, F>(v: &[T], mut f: F) -> TypeContents where
Expand Down Expand Up @@ -4129,7 +4099,7 @@ impl<'tcx> TyS<'tcx> {
let result = match ty.sty {
// usize and isize are ffi-unsafe
TyUint(ast::TyUs) | TyInt(ast::TyIs) => {
TC::ReachesFfiUnsafe
TC::None
}

// Scalar and unique types are sendable, and durable
Expand All @@ -4140,40 +4110,35 @@ impl<'tcx> TyS<'tcx> {
}

TyBox(typ) => {
TC::ReachesFfiUnsafe | tc_ty(cx, typ, cache).owned_pointer()
tc_ty(cx, typ, cache).owned_pointer()
}

TyTrait(box TraitTy { ref bounds, .. }) => {
object_contents(bounds) | TC::ReachesFfiUnsafe | TC::Nonsized
TyTrait(_) => {
TC::All - TC::InteriorParam
}

TyRawPtr(ref mt) => {
tc_ty(cx, mt.ty, cache).unsafe_pointer()
TyRawPtr(_) => {
TC::None
}

TyRef(r, ref mt) => {
tc_ty(cx, mt.ty, cache).reference(borrowed_contents(*r, mt.mutbl)) |
TC::ReachesFfiUnsafe
TyRef(_, _) => {
TC::None
}

TyArray(ty, _) => {
tc_ty(cx, ty, cache)
}

TySlice(ty) => {
tc_ty(cx, ty, cache) | TC::Nonsized
tc_ty(cx, ty, cache)
}
TyStr => TC::Nonsized,
TyStr => TC::None,

TyStruct(did, substs) => {
let flds = cx.struct_fields(did, substs);
let mut res =
TypeContents::union(&flds[..],
|f| tc_mt(cx, f.mt, cache));

if !cx.lookup_repr_hints(did).contains(&attr::ReprExtern) {
res = res | TC::ReachesFfiUnsafe;
}
|f| tc_ty(cx, f.mt.ty, cache));

if cx.has_dtor(did) {
res = res | TC::OwnsDtor;
Expand All @@ -4182,7 +4147,6 @@ impl<'tcx> TyS<'tcx> {
}

TyClosure(did, substs) => {
// FIXME(#14449): `borrowed_contents` below assumes `&mut` closure.
let param_env = cx.empty_parameter_environment();
let infcx = infer::new_infer_ctxt(cx, &cx.tables, Some(param_env), false);
let upvars = infcx.closure_upvars(did, substs).unwrap();
Expand All @@ -4208,44 +4172,6 @@ impl<'tcx> TyS<'tcx> {
res = res | TC::OwnsDtor;
}

if !variants.is_empty() {
let repr_hints = cx.lookup_repr_hints(did);
if repr_hints.len() > 1 {
// this is an error later on, but this type isn't safe
res = res | TC::ReachesFfiUnsafe;
}

match repr_hints.get(0) {
Some(h) => if !h.is_ffi_safe() {
res = res | TC::ReachesFfiUnsafe;
},
// ReprAny
None => {
res = res | TC::ReachesFfiUnsafe;

// We allow ReprAny enums if they are eligible for
// the nullable pointer optimization and the
// contained type is an `extern fn`

if variants.len() == 2 {
let mut data_idx = 0;

if variants[0].args.is_empty() {
data_idx = 1;
}

if variants[data_idx].args.len() == 1 {
match variants[data_idx].args[0].sty {
TyBareFn(..) => { res = res - TC::ReachesFfiUnsafe; }
_ => { }
}
}
}
}
}
}


apply_lang_items(cx, did, res)
}

Expand All @@ -4264,14 +4190,6 @@ impl<'tcx> TyS<'tcx> {
result
}

fn tc_mt<'tcx>(cx: &ctxt<'tcx>,
mt: TypeAndMut<'tcx>,
cache: &mut FnvHashMap<Ty<'tcx>, TypeContents>) -> TypeContents
{
let mc = TC::ReachesMutable.when(mt.mutbl == MutMutable);
mc | tc_ty(cx, mt.ty, cache)
}

fn apply_lang_items(cx: &ctxt, did: ast::DefId, tc: TypeContents)
-> TypeContents {
if Some(did) == cx.lang_items.unsafe_cell_type() {
Expand All @@ -4280,32 +4198,6 @@ impl<'tcx> TyS<'tcx> {
tc
}
}

/// Type contents due to containing a reference with
/// the region `region` and borrow kind `bk`.
fn borrowed_contents(region: ty::Region,
mutbl: ast::Mutability)
-> TypeContents {
let b = match mutbl {
ast::MutMutable => TC::ReachesMutable,
ast::MutImmutable => TC::None,
};
b | (TC::ReachesBorrowed).when(region != ty::ReStatic)
}

fn object_contents(bounds: &ExistentialBounds) -> TypeContents {
// These are the type contents of the (opaque) interior. We
// make no assumptions (other than that it cannot have an
// in-scope type parameter within, which makes no sense).
let mut tc = TC::All - TC::InteriorParam;
for bound in &bounds.builtin_bounds {
tc = tc - match bound {
BoundSync | BoundSend | BoundCopy => TC::None,
BoundSized => TC::Nonsized,
};
}
return tc;
}
}

fn impls_bound<'a>(&'tcx self, param_env: &ParameterEnvironment<'a,'tcx>,
Expand Down Expand Up @@ -4399,10 +4291,6 @@ impl<'tcx> TyS<'tcx> {
result
}

pub fn is_ffi_safe(&'tcx self, cx: &ctxt<'tcx>) -> bool {
!self.type_contents(cx).intersects(TC::ReachesFfiUnsafe)
}

// True if instantiating an instance of `r_ty` requires an instance of `r_ty`.
pub fn is_instantiable(&'tcx self, cx: &ctxt<'tcx>) -> bool {
fn type_requires<'tcx>(cx: &ctxt<'tcx>, seen: &mut Vec<DefId>,
Expand Down

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