Fix #14865
Fixes a codegen bug which generates illegal non-terminated LLVM block when there are wildcard pattern with guard and enum patterns in a match expression. Also refactors the code a little. Closes #14865
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2 changed files with 42 additions and 42 deletions
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@ -518,8 +518,7 @@ fn enter_default<'a, 'b>(
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dm: &DefMap,
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m: &'a [Match<'a, 'b>],
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col: uint,
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val: ValueRef,
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chk: &FailureHandler)
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val: ValueRef)
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-> Vec<Match<'a, 'b>> {
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debug!("enter_default(bcx={}, m={}, col={}, val={})",
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bcx.to_str(),
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@ -529,35 +528,13 @@ fn enter_default<'a, 'b>(
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let _indenter = indenter();
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// Collect all of the matches that can match against anything.
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let matches = enter_match(bcx, dm, m, col, val, |p| {
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enter_match(bcx, dm, m, col, val, |p| {
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match p.node {
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ast::PatWild | ast::PatWildMulti => Some(Vec::new()),
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ast::PatIdent(_, _, None) if pat_is_binding(dm, &*p) => Some(Vec::new()),
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_ => None
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}
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});
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// Ok, now, this is pretty subtle. A "default" match is a match
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// that needs to be considered if none of the actual checks on the
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// value being considered succeed. The subtlety lies in that sometimes
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// identifier/wildcard matches are *not* default matches. Consider:
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// "match x { _ if something => foo, true => bar, false => baz }".
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// There is a wildcard match, but it is *not* a default case. The boolean
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// case on the value being considered is exhaustive. If the case is
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// exhaustive, then there are no defaults.
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//
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// We detect whether the case is exhaustive in the following
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// somewhat kludgy way: if the last wildcard/binding match has a
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// guard, then by non-redundancy, we know that there aren't any
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// non guarded matches, and thus by exhaustiveness, we know that
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// we don't need any default cases. If the check *isn't* nonexhaustive
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// (because chk is Some), then we need the defaults anyways.
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let is_exhaustive = match matches.last() {
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Some(m) if m.data.arm.guard.is_some() && chk.is_infallible() => true,
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_ => false
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};
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if is_exhaustive { Vec::new() } else { matches }
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})
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}
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// <pcwalton> nmatsakis: what does enter_opt do?
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@ -1448,15 +1425,12 @@ fn compile_submatch<'a, 'b>(
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m.repr(bcx.tcx()),
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vec_map_to_str(vals, |v| bcx.val_to_str(*v)));
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let _indenter = indenter();
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/*
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For an empty match, a fall-through case must exist
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*/
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assert!((m.len() > 0u || chk.is_fallible()));
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let _icx = push_ctxt("match::compile_submatch");
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let mut bcx = bcx;
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if m.len() == 0u {
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Br(bcx, chk.handle_fail());
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if chk.is_fallible() {
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Br(bcx, chk.handle_fail());
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}
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return;
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}
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if m[0].pats.len() == 0u {
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@ -1658,7 +1632,7 @@ fn compile_submatch_continue<'a, 'b>(
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C_int(ccx, 0) // Placeholder for when not using a switch
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};
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let defaults = enter_default(else_cx, dm, m, col, val, chk);
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let defaults = enter_default(else_cx, dm, m, col, val);
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let exhaustive = chk.is_infallible() && defaults.len() == 0u;
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let len = opts.len();
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@ -1947,18 +1921,14 @@ fn trans_match_inner<'a>(scope_cx: &'a Block<'a>,
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// `compile_submatch` works one column of arm patterns a time and
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// then peels that column off. So as we progress, it may become
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// impossible to know whether we have a genuine default arm, i.e.
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// impossible to tell whether we have a genuine default arm, i.e.
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// `_ => foo` or not. Sometimes it is important to know that in order
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// to decide whether moving on to the next condition or falling back
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// to the default arm.
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let has_default = arms.len() > 0 && {
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let ref pats = arms.last().unwrap().pats;
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pats.len() == 1
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&& match pats.last().unwrap().node {
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ast::PatWild => true, _ => false
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}
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};
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let has_default = arms.last().map_or(false, |arm| {
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arm.pats.len() == 1
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&& arm.pats.last().unwrap().node == ast::PatWild
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});
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compile_submatch(bcx, matches.as_slice(), [discr_datum.val], &chk, has_default);
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30
src/test/run-pass/issue-14865.rs
Normal file
30
src/test/run-pass/issue-14865.rs
Normal file
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@ -0,0 +1,30 @@
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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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enum X {
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Foo(uint),
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Bar(bool)
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}
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fn main() {
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let x = match Foo(42) {
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Foo(..) => 1,
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_ if true => 0,
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Bar(..) => fail!("Oh dear")
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};
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assert_eq!(x, 1);
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let x = match Foo(42) {
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_ if true => 0,
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Foo(..) => 1,
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Bar(..) => fail!("Oh dear")
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};
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assert_eq!(x, 0);
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}
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