Reverse #13034
It has been found that #13034 was flawed and caused regression #13867. This patch reveres the changes made by it except the companion tests.
This commit is contained in:
parent
8895f25241
commit
7adc48527f
|
@ -289,42 +289,6 @@ fn opt_eq(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
|
|||
}
|
||||
}
|
||||
|
||||
fn opt_overlap(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
|
||||
match (a, b) {
|
||||
(&lit(a), &lit(b)) => {
|
||||
let a_expr = lit_to_expr(tcx, &a);
|
||||
let b_expr = lit_to_expr(tcx, &b);
|
||||
match const_eval::compare_lit_exprs(tcx, a_expr, b_expr) {
|
||||
Some(val1) => val1 == 0,
|
||||
None => fail!("opt_overlap: type mismatch"),
|
||||
}
|
||||
}
|
||||
|
||||
(&range(a1, a2), &range(b1, b2)) => {
|
||||
let m1 = const_eval::compare_lit_exprs(tcx, a1, b2);
|
||||
let m2 = const_eval::compare_lit_exprs(tcx, b1, a2);
|
||||
match (m1, m2) {
|
||||
// two ranges [a1, a2] and [b1, b2] overlap iff:
|
||||
// a1 <= b2 && b1 <= a2
|
||||
(Some(val1), Some(val2)) => (val1 <= 0 && val2 <= 0),
|
||||
_ => fail!("opt_overlap: type mismatch"),
|
||||
}
|
||||
}
|
||||
|
||||
(&range(a1, a2), &lit(b)) | (&lit(b), &range(a1, a2)) => {
|
||||
let b_expr = lit_to_expr(tcx, &b);
|
||||
let m1 = const_eval::compare_lit_exprs(tcx, a1, b_expr);
|
||||
let m2 = const_eval::compare_lit_exprs(tcx, a2, b_expr);
|
||||
match (m1, m2) {
|
||||
// b is in range [a1, a2] iff a1 <= b and b <= a2
|
||||
(Some(val1), Some(val2)) => (val1 <= 0 && 0 <= val2),
|
||||
_ => fail!("opt_overlap: type mismatch"),
|
||||
}
|
||||
}
|
||||
_ => fail!("opt_overlap: expect lit or range")
|
||||
}
|
||||
}
|
||||
|
||||
pub enum opt_result<'a> {
|
||||
single_result(Result<'a>),
|
||||
lower_bound(Result<'a>),
|
||||
|
@ -634,30 +598,16 @@ fn enter_opt<'a, 'b>(
|
|||
let tcx = bcx.tcx();
|
||||
let dummy = @ast::Pat {id: 0, node: ast::PatWild, span: DUMMY_SP};
|
||||
let mut i = 0;
|
||||
// By the virtue of fact that we are in `trans` already, `enter_opt` is able
|
||||
// to prune sub-match tree aggressively based on exact equality. But when it
|
||||
// comes to literal or range, that strategy may lead to wrong result if there
|
||||
// are guard function or multiple patterns inside tuple; in that case, pruning
|
||||
// based on the overlap of patterns is required.
|
||||
//
|
||||
// Ideally, when constructing the sub-match tree for certain arm, only those
|
||||
// arms beneath it matter. But that isn't how algorithm works right now and
|
||||
// all other arms are taken into consideration when computing `guarded` below.
|
||||
// That is ok since each round of `compile_submatch` guarantees to trim one
|
||||
// "column" of arm patterns and the algorithm will converge.
|
||||
let guarded = m.iter().any(|x| x.data.arm.guard.is_some());
|
||||
let multi_pats = m.len() > 0 && m[0].pats.len() > 1;
|
||||
enter_match(bcx, &tcx.def_map, m, col, val, |p| {
|
||||
let answer = match p.node {
|
||||
ast::PatEnum(..) |
|
||||
ast::PatIdent(_, _, None) if pat_is_const(&tcx.def_map, p) => {
|
||||
let const_def = tcx.def_map.borrow().get_copy(&p.id);
|
||||
let const_def_id = ast_util::def_id_of_def(const_def);
|
||||
let konst = lit(ConstLit(const_def_id));
|
||||
match guarded || multi_pats {
|
||||
false if opt_eq(tcx, &konst, opt) => Some(Vec::new()),
|
||||
true if opt_overlap(tcx, &konst, opt) => Some(Vec::new()),
|
||||
_ => None,
|
||||
if opt_eq(tcx, &lit(ConstLit(const_def_id)), opt) {
|
||||
Some(Vec::new())
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
ast::PatEnum(_, ref subpats) => {
|
||||
|
@ -682,20 +632,12 @@ fn enter_opt<'a, 'b>(
|
|||
}
|
||||
}
|
||||
ast::PatLit(l) => {
|
||||
let lit_expr = lit(ExprLit(l));
|
||||
match guarded || multi_pats {
|
||||
false if opt_eq(tcx, &lit_expr, opt) => Some(Vec::new()),
|
||||
true if opt_overlap(tcx, &lit_expr, opt) => Some(Vec::new()),
|
||||
_ => None,
|
||||
}
|
||||
if opt_eq(tcx, &lit(ExprLit(l)), opt) { Some(Vec::new()) }
|
||||
else { None }
|
||||
}
|
||||
ast::PatRange(l1, l2) => {
|
||||
let rng = range(l1, l2);
|
||||
match guarded || multi_pats {
|
||||
false if opt_eq(tcx, &rng, opt) => Some(Vec::new()),
|
||||
true if opt_overlap(tcx, &rng, opt) => Some(Vec::new()),
|
||||
_ => None,
|
||||
}
|
||||
if opt_eq(tcx, &range(l1, l2), opt) { Some(Vec::new()) }
|
||||
else { None }
|
||||
}
|
||||
ast::PatStruct(_, ref field_pats, _) => {
|
||||
if opt_eq(tcx, &variant_opt(bcx, p.id), opt) {
|
||||
|
|
Loading…
Reference in New Issue