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rustc: Implement "@Foo as @Bar" for boxed traits

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This commit is contained in:
Patrick Walton
2012-10-03 15:18:50 -07:00
parent d936773e56
commit b34327be0d
3 changed files with 89 additions and 31 deletions
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4
src/rustc/middle/astencode.rs
View File

@@ -929,6 +929,8 @@ fn decode_side_tables(xcx: extended_decode_ctxt,
if tag == (c::tag_table_mutbl as uint) {
dcx.maps.mutbl_map.insert(id, ());
} else if tag == (c::tag_table_legacy_boxed_trait as uint) {
dcx.tcx.legacy_boxed_traits.insert(id, ());
} else {
let val_doc = entry_doc[c::tag_table_val as uint];
let val_dsr = ebml::ebml_deserializer(val_doc);
@@ -969,8 +971,6 @@ fn decode_side_tables(xcx: extended_decode_ctxt,
} else if tag == (c::tag_table_adjustments as uint) {
let adj = @ty::deserialize_AutoAdjustment(val_dsr).tr(xcx);
dcx.tcx.adjustments.insert(id, adj);
} else if tag == (c::tag_table_legacy_boxed_trait as uint) {
dcx.tcx.legacy_boxed_traits.insert(id, ());
} else {
xcx.dcx.tcx.sess.bug(
fmt!("unknown tag found in side tables: %x", tag));

27
src/rustc/middle/trans/meth.rs
View File

@@ -536,6 +536,7 @@ fn trans_trait_cast(bcx: block,
dest: expr::Dest)
-> block
{
let mut bcx = bcx;
let _icx = bcx.insn_ctxt("impl::trans_cast");
let lldest = match dest {
@@ -548,16 +549,24 @@ fn trans_trait_cast(bcx: block,
let ccx = bcx.ccx();
let v_ty = expr_ty(bcx, val);
// Allocate an @ box and store the value into it
let {bcx: bcx, box: llbox, body: body} = malloc_boxed(bcx, v_ty);
add_clean_free(bcx, llbox, heap_shared);
let bcx = expr::trans_into(bcx, val, SaveIn(body));
revoke_clean(bcx, llbox);
let mut llboxdest = GEPi(bcx, lldest, [0u, 1u]);
llboxdest = PointerCast(bcx, llboxdest,
T_ptr(type_of::type_of(bcx.ccx(), v_ty)));
// Store the @ box into the pair
Store(bcx, llbox, PointerCast(bcx,
GEPi(bcx, lldest, [0u, 1u]),
T_ptr(val_ty(llbox))));
if bcx.tcx().legacy_boxed_traits.contains_key(id) {
// Allocate an @ box and store the value into it
let {bcx: new_bcx, box: llbox, body: body} = malloc_boxed(bcx, v_ty);
bcx = new_bcx;
add_clean_free(bcx, llbox, heap_shared);
bcx = expr::trans_into(bcx, val, SaveIn(body));
revoke_clean(bcx, llbox);
// Store the @ box into the pair
Store(bcx, llbox, llboxdest);
} else {
// Just store the @ box into the pair.
bcx = expr::trans_into(bcx, val, SaveIn(llboxdest));
}
// Store the vtable into the pair
let orig = ccx.maps.vtable_map.get(id)[0];

89
src/rustc/middle/typeck/check/vtable.rs
View File

@@ -51,8 +51,18 @@ fn lookup_vtables(fcx: @fn_ctxt,
match *bound {
ty::bound_trait(i_ty) => {
let i_ty = ty::subst(tcx, substs, i_ty);
result.push(lookup_vtable(fcx, expr, *ty, i_ty,
allow_unsafe, is_early));
match lookup_vtable(fcx, expr, *ty, i_ty, allow_unsafe,
is_early) {
Some(vtable) => result.push(vtable),
None => {
fcx.tcx().sess.span_fatal(
expr.span,
fmt!("failed to find an implementation of trait \
%s for %s",
ty_to_str(fcx.tcx(), i_ty),
ty_to_str(fcx.tcx(), *ty)));
}
}
}
_ => ()
}
@@ -91,7 +101,7 @@ fn lookup_vtable(fcx: @fn_ctxt,
trait_ty: ty::t,
allow_unsafe: bool,
is_early: bool)
-> vtable_origin
-> Option<vtable_origin>
{
debug!("lookup_vtable(ty=%s, trait_ty=%s)",
@@ -113,7 +123,7 @@ fn lookup_vtable(fcx: @fn_ctxt,
// The type has unconstrained type variables in it, so we can't
// do early resolution on it. Return some completely bogus vtable
// information: we aren't storing it anyways.
return vtable_param(0, 0);
return Some(vtable_param(0, 0));
}
};
@@ -135,7 +145,7 @@ fn lookup_vtable(fcx: @fn_ctxt,
idid);
relate_trait_tys(fcx, expr,
trait_ty, ity);
return vtable_param(n, n_bound);
return Some(vtable_param(n, n_bound));
}
}
_ => tcx.sess.impossible_case(
@@ -170,7 +180,7 @@ fn lookup_vtable(fcx: @fn_ctxt,
}
}
}
return vtable_trait(did, substs.tps);
return Some(vtable_trait(did, substs.tps));
}
_ => {
@@ -303,7 +313,7 @@ fn lookup_vtable(fcx: @fn_ctxt,
None => {
assert is_early;
// Bail out with a bogus answer
return vtable_param(0, 0);
return Some(vtable_param(0, 0));
}
};
@@ -341,23 +351,20 @@ fn lookup_vtable(fcx: @fn_ctxt,
match found.len() {
0 => { /* fallthrough */ }
1 => { return found[0]; }
1 => { return Some(found[0]); }
_ => {
if !is_early {
fcx.ccx.tcx.sess.span_err(
expr.span,
~"multiple applicable methods in scope");
}
return found[0];
return Some(found[0]);
}
}
}
}
tcx.sess.span_fatal(
expr.span,
fmt!("failed to find an implementation of trait %s for %s",
ty_to_str(tcx, trait_ty), ty_to_str(tcx, ty)));
return None;
}
fn fixup_ty(fcx: @fn_ctxt,
@@ -459,13 +466,55 @@ fn early_resolve_expr(ex: @ast::expr, &&fcx: @fn_ctxt, is_early: bool) {
Look up vtables for the type we're casting to,
passing in the source and target type
*/
let vtable = lookup_vtable(fcx, ex, fcx.expr_ty(src),
target_ty, true, is_early);
/*
Map this expression to that vtable (that is: "ex has
vtable <vtable>")
*/
if !is_early { cx.vtable_map.insert(ex.id, @~[vtable]); }
let ty = fcx.expr_ty(src);
let vtable_opt = lookup_vtable(fcx, ex, ty, target_ty, true,
is_early);
match vtable_opt {
None => {
// Try the new-style boxed trait; "@int as @Trait".
let mut err = false;
let ty = structurally_resolved_type(fcx, ex.span, ty);
match ty::get(ty).sty {
ty::ty_box(boxed_ty) => {
let vtable_opt = lookup_vtable(fcx, ex,
boxed_ty.ty,
target_ty, true,
is_early);
match vtable_opt {
Some(vtable) => {
/*
Map this expression to that vtable (that
is: "ex has vtable <vtable>")
*/
if !is_early {
cx.vtable_map.insert(ex.id,
@~[vtable]);
}
}
None => err = true
}
}
_ => err = true
}
if err {
fcx.tcx().sess.span_fatal(
ex.span,
fmt!("failed to find an implementation of trait \
%s for %s",
ty_to_str(fcx.tcx(), target_ty),
ty_to_str(fcx.tcx(), ty)));
}
}
Some(vtable) => {
/*
Map this expression to that vtable (that is: "ex has
vtable <vtable>")
*/
if !is_early { cx.vtable_map.insert(ex.id, @~[vtable]); }
fcx.tcx().legacy_boxed_traits.insert(ex.id, ());
}
}
}
_ => ()
}