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Check existential type contents against destination trait bounds.

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This commit is contained in:
Ben Blum 2013-06-19 17:58:04 -04:00
parent 1ffcc6fc82
commit 1d2b20ee2c
1 changed files with 31 additions and 25 deletions
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56
src/librustc/middle/kind.rs
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@ -291,7 +291,13 @@ pub fn check_expr(e: @expr, (cx, v): (Context, visit::vt<Context>)) {
match e.node {
expr_cast(source, _) => {
check_cast_for_escaping_regions(cx, source, e);
check_kind_bounds_of_cast(cx, source, e);
match ty::get(ty::expr_ty(cx.tcx, e)).sty {
ty::ty_trait(_, _, store, _, bounds) => {
let source_ty = ty::expr_ty(cx.tcx, source);
check_trait_cast_bounds(cx, e.span, source_ty, bounds, store)
}
_ => { }
}
}
expr_copy(expr) => {
// Note: This is the only place where we must check whether the
@ -335,8 +341,9 @@ fn check_ty(aty: @Ty, (cx, v): (Context, visit::vt<Context>)) {
visit::visit_ty(aty, (cx, v));
}
pub fn check_builtin_bounds(cx: Context, ty: ty::t, bounds: ty::BuiltinBounds)
-> ty::BuiltinBounds // returns the missing bounds
// Calls "any_missing" if any bounds were missing.
pub fn check_builtin_bounds(cx: Context, ty: ty::t, bounds: ty::BuiltinBounds,
any_missing: &fn(ty::BuiltinBounds))
{
let kind = ty::type_contents(cx.tcx, ty);
let mut missing = ty::EmptyBuiltinBounds();
@ -345,7 +352,9 @@ pub fn check_builtin_bounds(cx: Context, ty: ty::t, bounds: ty::BuiltinBounds)
missing.add(bound);
}
}
missing
if !missing.is_empty() {
any_missing(missing);
}
}
pub fn check_typaram_bounds(cx: Context,
@ -354,8 +363,7 @@ pub fn check_typaram_bounds(cx: Context,
ty: ty::t,
type_param_def: &ty::TypeParameterDef)
{
let missing = check_builtin_bounds(cx, ty, type_param_def.bounds.builtin_bounds);
if !missing.is_empty() {
do check_builtin_bounds(cx, ty, type_param_def.bounds.builtin_bounds) |missing| {
cx.tcx.sess.span_err(
sp,
fmt!("instantiating a type parameter with an incompatible type \
@ -368,8 +376,7 @@ pub fn check_typaram_bounds(cx: Context,
pub fn check_freevar_bounds(cx: Context, sp: span, ty: ty::t,
bounds: ty::BuiltinBounds)
{
let missing = check_builtin_bounds(cx, ty, bounds);
if !missing.is_empty() {
do check_builtin_bounds(cx, ty, bounds) |missing| {
cx.tcx.sess.span_err(
sp,
fmt!("cannot capture variable of type `%s`, which does not fulfill \
@ -382,6 +389,22 @@ pub fn check_freevar_bounds(cx: Context, sp: span, ty: ty::t,
}
}
pub fn check_trait_cast_bounds(cx: Context, sp: span, ty: ty::t,
bounds: ty::BuiltinBounds, store: ty::TraitStore) {
do check_builtin_bounds(cx, ty, bounds) |missing| {
cx.tcx.sess.span_err(sp,
fmt!("cannot pack type `%s`, which does not fulfill \
`%s`, as a trait bounded by %s",
ty_to_str(cx.tcx, ty), missing.user_string(cx.tcx),
bounds.user_string(cx.tcx)));
}
// FIXME(#3569): Remove this check when the corresponding restriction
// is made with type contents.
if store == ty::UniqTraitStore && !ty::type_is_owned(cx.tcx, ty) {
cx.tcx.sess.span_err(sp, "uniquely-owned trait objects must be sendable");
}
}
fn is_nullary_variant(cx: Context, ex: @expr) -> bool {
match ex.node {
expr_path(_) => {
@ -564,20 +587,3 @@ pub fn check_cast_for_escaping_regions(
cx.tcx.region_maps.is_subregion_of(r_sub, r_sup)
}
}
/// Ensures that values placed into a ~Trait are copyable and sendable.
pub fn check_kind_bounds_of_cast(cx: Context, source: @expr, target: @expr) {
let target_ty = ty::expr_ty(cx.tcx, target);
match ty::get(target_ty).sty {
// FIXME(#3569) kind check bounds here
ty::ty_trait(_, _, ty::UniqTraitStore, _, _bounds) => {
let source_ty = ty::expr_ty(cx.tcx, source);
if !ty::type_is_owned(cx.tcx, source_ty) {
cx.tcx.sess.span_err(
target.span,
"uniquely-owned trait objects must be sendable");
}
}
_ => {} // Nothing to do.
}
}