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Fix unboxing in alias pass

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The alias checker would only deref once for autoderef, and only deref
boxes. It should now do the right thing. Closes #725.
This commit is contained in:
Marijn Haverbeke 2011-07-22 09:29:01 +02:00
parent 1348a383c3
commit 93ffed4c16
2 changed files with 35 additions and 15 deletions
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42
src/comp/middle/alias.rs
View File

@ -521,20 +521,32 @@ type deref = @rec(bool mut, deref_t kind, ty::t outer_t);
// ds=[field(baz),field(bar)])
fn expr_root(&ctx cx, @ast::expr ex, bool autoderef) ->
rec(@ast::expr ex, @deref[] ds) {
fn maybe_auto_unbox(&ctx cx, &ty::t t) ->
rec(ty::t t, option::t[deref] d) {
alt (ty::struct(cx.tcx, t)) {
case (ty::ty_box(?mt)) {
ret rec(t=mt.ty,
d=some(@rec(mut=mt.mut != ast::imm,
kind=unbox,
outer_t=t)));
fn maybe_auto_unbox(&ctx cx, ty::t t) -> rec(ty::t t, deref[] ds) {
auto ds = ~[];
while (true) {
alt (ty::struct(cx.tcx, t)) {
ty::ty_box(?mt) {
ds += ~[@rec(mut=mt.mut != ast::imm, kind=unbox, outer_t=t)];
t = mt.ty;
}
ty::ty_res(_, ?inner, ?tps) {
ds += ~[@rec(mut=false, kind=unbox, outer_t=t)];
t = ty::substitute_type_params(cx.tcx, tps, inner);
}
ty::ty_tag(?did, ?tps) {
auto variants = ty::tag_variants(cx.tcx, did);
if (ivec::len(variants) != 1u ||
ivec::len(variants.(0).args) != 1u) {
break;
}
ds += ~[@rec(mut=false, kind=unbox, outer_t=t)];
t = ty::substitute_type_params(cx.tcx, tps,
variants.(0).args.(0));
}
_ { break; }
}
case (_) { ret rec(t=t, d=none); }
}
}
fn maybe_push_auto_unbox(&option::t[deref] d, &mutable deref[] ds) {
alt (d) { case (some(?d)) { ds += ~[d]; } case (none) { } }
ret rec(t=t, ds=ds);
}
let deref[] ds = ~[];
while (true) {
@ -559,7 +571,7 @@ fn expr_root(&ctx cx, @ast::expr ex, bool autoderef) ->
case (ty::ty_obj(_)) { }
}
ds += ~[@rec(mut=mut, kind=field, outer_t=auto_unbox.t)];
maybe_push_auto_unbox(auto_unbox.d, ds);
ds += auto_unbox.ds;
ex = base;
}
case (ast::expr_index(?base, _)) {
@ -577,7 +589,7 @@ fn expr_root(&ctx cx, @ast::expr ex, bool autoderef) ->
outer_t=auto_unbox.t)];
}
}
maybe_push_auto_unbox(auto_unbox.d, ds);
ds += auto_unbox.ds;
ex = base;
}
case (ast::expr_unary(?op, ?base)) {
@ -599,7 +611,7 @@ fn expr_root(&ctx cx, @ast::expr ex, bool autoderef) ->
}
if (autoderef) {
auto auto_unbox = maybe_auto_unbox(cx, ty::expr_ty(cx.tcx, ex));
maybe_push_auto_unbox(auto_unbox.d, ds);
ds += auto_unbox.ds;
}
ret rec(ex=ex, ds=@ds);
}

8
src/test/run-pass/double-unbox.rs Normal file
View File

@ -0,0 +1,8 @@
type quux = rec(int bar);
fn g(&int i) { }
fn f(@@quux foo) {
g(foo.bar);
}
fn main() {}