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Allow pure fns to have any return type

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This commit is contained in:
Tim Chevalier 2011-08-24 17:24:58 -07:00
parent 4dd23f24d6
commit e241f2996d
5 changed files with 47 additions and 15 deletions
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7
src/comp/middle/ty.rs
View file

@ -55,6 +55,7 @@ export hash_ty;
export idx_nil;
export is_lval;
export is_binopable;
export is_pred_ty;
export item_table;
export lookup_item_type;
export method;
@ -1737,6 +1738,12 @@ fn is_fn_ty(cx: &ctxt, fty: t) -> bool {
}
}
// Just checks whether it's a fn that returns bool,
// not its purity.
fn is_pred_ty(cx: &ctxt, fty:t) -> bool {
is_fn_ty(cx, fty) && type_is_bool(cx, ty_fn_ret(cx, fty))
}
fn ty_var_id(cx: &ctxt, typ: t) -> int {
alt struct(cx, typ) {
ty::ty_var(vid) { ret vid; }

19
src/comp/middle/typeck.rs
View file

@ -1715,6 +1715,11 @@ fn check_expr_with_unifier(fcx: &@fn_ctxt, expr: &@ast::expr, unify: &unifier,
literals or slots */
alt e.node {
ast::expr_call(operator, operands) {
if !ty::is_pred_ty(fcx.ccx.tcx, expr_ty(fcx.ccx.tcx, operator)) {
fcx.ccx.tcx.sess.span_fatal(operator.span,
"Operator in constraint has non-boolean return type");
}
alt operator.node {
ast::expr_path(oper_name) {
alt fcx.ccx.tcx.def_map.find(operator.id) {
@ -1723,7 +1728,7 @@ fn check_expr_with_unifier(fcx: &@fn_ctxt, expr: &@ast::expr, unify: &unifier,
}
_ {
fcx.ccx.tcx.sess.span_fatal(operator.span,
"non-predicate as operator \
"Impure function as operator \
in constraint");
}
}
@ -2596,18 +2601,6 @@ fn check_fn(ccx: &@crate_ctxt, f: &ast::_fn, id: &ast::node_id,
mutable fixups: fixups,
ccx: ccx};
check_block(fcx, body);
alt decl.purity {
ast::pure_fn. {
// This just checks that the declared type is bool, and trusts
// that that's the actual return type.
if !ty::type_is_bool(ccx.tcx, fcx.ret_ty) {
ccx.tcx.sess.span_err(body.span,
"Non-boolean return type in pred");
}
}
_ { }
}
// For non-iterator fns, we unify the tail expr's type with the
// function result type, if there is a tail expr.