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rustc: Report type errors in terms of the actual types involved, not type variables

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This commit is contained in:
Patrick Walton 2011-06-09 17:23:15 -07:00
parent 5318248f24
commit c9c1d860f1
1 changed files with 13 additions and 2 deletions
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15
src/comp/middle/typeck.rs
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@ -896,6 +896,14 @@ fn count_boxes(&@fn_ctxt fcx, &span sp, &ty::t t) -> uint {
}
fn resolve_type_vars_if_possible(&@fn_ctxt fcx, ty::t typ) -> ty::t {
alt (ty::unify::fixup_vars(fcx.ccx.tcx, fcx.var_bindings, typ)) {
case (fix_ok(?new_type)) { ret new_type; }
case (fix_err(_)) { ret typ; }
}
}
// Demands - procedures that require that two types unify and emit an error
// message if they don't.
@ -956,10 +964,13 @@ fn full(&@fn_ctxt fcx, &span sp, &ty::t expected, &ty::t actual,
}
case (ures_err(?err)) {
auto e_err = resolve_type_vars_if_possible(fcx, expected_1);
auto a_err = resolve_type_vars_if_possible(fcx, actual_1);
fcx.ccx.tcx.sess.span_err
(sp, "mismatched types: expected "
+ ty_to_str(fcx.ccx.tcx, expected_1) + " but found "
+ ty_to_str(fcx.ccx.tcx, actual_1) + " ("
+ ty_to_str(fcx.ccx.tcx, e_err) + " but found "
+ ty_to_str(fcx.ccx.tcx, a_err) + " ("
+ ty::type_err_to_str(err) + ")");
// TODO: In the future, try returning "expected", reporting