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rustc: Allow dereference expressions to be used as lvalues. Add a test case.

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This commit is contained in:
Patrick Walton 2011-04-07 12:50:37 -07:00
parent b4422cca21
commit 015c0d0d59
2 changed files with 32 additions and 20 deletions
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46
src/comp/middle/trans.rs
View File

@ -2591,15 +2591,9 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
ret res(sub.bcx, box);
}
case (ast.deref) {
auto val = sub.bcx.build.GEP(sub.val,
vec(C_int(0),
C_int(abi.box_rc_field_body)));
auto e_ty = node_ann_type(sub.bcx.fcx.ccx, a);
if (ty.type_is_scalar(e_ty) ||
ty.type_is_nil(e_ty)) {
val = sub.bcx.build.Load(val);
}
ret res(sub.bcx, val);
log "deref expressions should have been translated using " +
"trans_lval(), not trans_unary()";
fail;
}
}
fail;
@ -3908,6 +3902,15 @@ fn trans_lval(@block_ctxt cx, @ast.expr e) -> lval_result {
case (ast.expr_index(?base, ?idx, ?ann)) {
ret trans_index(cx, e.span, base, idx, ann);
}
case (ast.expr_unary(?unop, ?base, ?ann)) {
check (unop == ast.deref);
auto sub = trans_expr(cx, base);
auto val = sub.bcx.build.GEP(sub.val,
vec(C_int(0),
C_int(abi.box_rc_field_body)));
ret lval_mem(sub.bcx, val);
}
// Kind of bizarre to pass an *entire* self-call here...but let's try
// it
@ -3925,7 +3928,9 @@ fn trans_lval(@block_ctxt cx, @ast.expr e) -> lval_result {
}
}
case (_) { cx.fcx.ccx.sess.unimpl("expr variant in trans_lval"); }
case (_) {
cx.fcx.ccx.sess.span_unimpl(e.span, "expr variant in trans_lval");
}
}
fail;
}
@ -4685,7 +4690,9 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
}
case (ast.expr_unary(?op, ?x, ?ann)) {
ret trans_unary(cx, op, x, ann);
if (op != ast.deref) {
ret trans_unary(cx, op, x, ann);
}
}
case (ast.expr_binary(?op, ?x, ?y, _)) {
@ -4832,18 +4839,17 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
ret trans_recv(cx, lhs, rhs, ann);
}
// lval cases fall through to trans_lval and then
// possibly load the result (if it's non-structural).
case (_) {
auto t = ty.expr_ty(e);
auto sub = trans_lval(cx, e);
ret res(sub.res.bcx,
load_scalar_or_boxed(sub.res.bcx, sub.res.val, t));
// The expression is an lvalue. Fall through.
}
}
cx.fcx.ccx.sess.unimpl("expr variant in trans_expr");
fail;
// lval cases fall through to trans_lval and then
// possibly load the result (if it's non-structural).
auto t = ty.expr_ty(e);
auto sub = trans_lval(cx, e);
ret res(sub.res.bcx, load_scalar_or_boxed(sub.res.bcx, sub.res.val, t));
}
// We pass structural values around the compiler "by pointer" and

6
src/test/run-pass/deref-lval.rs Normal file
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@ -0,0 +1,6 @@
fn main() {
auto x = @mutable 5;
*x = 1000;
log *x;
}