Skip to content

Fix #12285 #15388

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from Jul 4, 2014
Merged

Fix #12285 #15388

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
124 changes: 51 additions & 73 deletions src/librustc/middle/check_match.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -93,9 +93,10 @@ pub enum Constructor {
Slice(uint)
}

#[deriving(Clone)]
#[deriving(Clone, PartialEq)]
enum Usefulness {
Useful(Vec<Gc<Pat>>),
Useful,
UsefulWithWitness(Vec<Gc<Pat>>),
NotUseful
}

Expand All @@ -104,15 +105,6 @@ enum WitnessPreference {
LeaveOutWitness
}

impl Usefulness {
fn useful(self) -> Option<Vec<Gc<Pat>>> {
match self {
Useful(pats) => Some(pats),
_ => None
}
}
}

impl<'a> Visitor<()> for MatchCheckCtxt<'a> {
fn visit_expr(&mut self, ex: &Expr, _: ()) {
check_expr(self, ex);
Expand Down Expand Up @@ -203,7 +195,8 @@ fn check_arms(cx: &MatchCheckCtxt, arms: &[Arm]) {
let v = vec!(*pat);
match is_useful(cx, &seen, v.as_slice(), LeaveOutWitness) {
NotUseful => cx.tcx.sess.span_err(pat.span, "unreachable pattern"),
_ => ()
Useful => (),
UsefulWithWitness(_) => unreachable!()
}
if arm.guard.is_none() {
let Matrix(mut rows) = seen;
Expand All @@ -223,7 +216,7 @@ fn raw_pat(p: Gc<Pat>) -> Gc<Pat> {

fn check_exhaustive(cx: &MatchCheckCtxt, sp: Span, m: &Matrix) {
match is_useful(cx, m, [wild()], ConstructWitness) {
Useful(pats) => {
UsefulWithWitness(pats) => {
let witness = match pats.as_slice() {
[witness] => witness,
[] => wild(),
Expand All @@ -234,7 +227,8 @@ fn check_exhaustive(cx: &MatchCheckCtxt, sp: Span, m: &Matrix) {
}
NotUseful => {
// This is good, wildcard pattern isn't reachable
}
},
_ => unreachable!()
}
}

Expand Down Expand Up @@ -404,11 +398,14 @@ fn all_constructors(cx: &MatchCheckCtxt, left_ty: ty::t,

// Note: is_useful doesn't work on empty types, as the paper notes.
// So it assumes that v is non-empty.
fn is_useful(cx: &MatchCheckCtxt, m @ &Matrix(ref rows): &Matrix,
fn is_useful(cx: &MatchCheckCtxt, matrix @ &Matrix(ref rows): &Matrix,
v: &[Gc<Pat>], witness: WitnessPreference) -> Usefulness {
debug!("{:}", m);
debug!("{:}", matrix);
if rows.len() == 0u {
return Useful(vec!());
return match witness {
ConstructWitness => UsefulWithWitness(vec!()),
LeaveOutWitness => Useful
};
}
if rows.get(0).len() == 0u {
return NotUseful;
Expand Down Expand Up @@ -438,53 +435,46 @@ fn is_useful(cx: &MatchCheckCtxt, m @ &Matrix(ref rows): &Matrix,

let constructors = pat_constructors(cx, v[0], left_ty, max_slice_length);
if constructors.is_empty() {
match missing_constructor(cx, m, left_ty, max_slice_length) {
match missing_constructor(cx, matrix, left_ty, max_slice_length) {
None => {
all_constructors(cx, left_ty, max_slice_length).move_iter().filter_map(|c| {
is_useful_specialized(cx, m, v, c.clone(),
left_ty, witness).useful().map(|pats| {
Useful(match witness {
ConstructWitness => {
let arity = constructor_arity(cx, &c, left_ty);
let subpats = {
let pat_slice = pats.as_slice();
Vec::from_fn(arity, |i| {
pat_slice.get(i).map(|p| p.clone())
.unwrap_or_else(|| wild())
})
};
let mut result = vec!(construct_witness(cx, &c, subpats, left_ty));
result.extend(pats.move_iter().skip(arity));
result
}
LeaveOutWitness => vec!()
})
})
}).nth(0).unwrap_or(NotUseful)
all_constructors(cx, left_ty, max_slice_length).move_iter().map(|c| {
match is_useful_specialized(cx, matrix, v, c.clone(), left_ty, witness) {
UsefulWithWitness(pats) => UsefulWithWitness({
let arity = constructor_arity(cx, &c, left_ty);
let subpats = {
let pat_slice = pats.as_slice();
Vec::from_fn(arity, |i| {
pat_slice.get(i).map(|p| p.clone())
.unwrap_or_else(|| wild())
})
};
let mut result = vec!(construct_witness(cx, &c, subpats, left_ty));
result.extend(pats.move_iter().skip(arity));
result
}),
result => result
}
}).find(|result| result != &NotUseful).unwrap_or(NotUseful)
},

Some(constructor) => {
let matrix = Matrix(rows.iter().filter_map(|r|
default(cx, r.as_slice())).collect());
match is_useful(cx, &matrix, v.tail(), witness) {
Useful(pats) => Useful(match witness {
ConstructWitness => {
let arity = constructor_arity(cx, &constructor, left_ty);
let wild_pats = Vec::from_elem(arity, wild());
let enum_pat = construct_witness(cx, &constructor, wild_pats, left_ty);
(vec!(enum_pat)).append(pats.as_slice())
}
LeaveOutWitness => vec!()
}),
UsefulWithWitness(pats) => {
let arity = constructor_arity(cx, &constructor, left_ty);
let wild_pats = Vec::from_elem(arity, wild());
let enum_pat = construct_witness(cx, &constructor, wild_pats, left_ty);
UsefulWithWitness(vec!(enum_pat).append(pats.as_slice()))
},
result => result
}
}
}
} else {
constructors.move_iter().filter_map(|c| {
is_useful_specialized(cx, m, v, c.clone(), left_ty, witness)
.useful().map(|pats| Useful(pats))
}).nth(0).unwrap_or(NotUseful)
constructors.move_iter().map(|c|
is_useful_specialized(cx, matrix, v, c.clone(), left_ty, witness)
).find(|result| result != &NotUseful).unwrap_or(NotUseful)
}
}

Expand Down Expand Up @@ -519,6 +509,7 @@ fn pat_constructors(cx: &MatchCheckCtxt, p: Gc<Pat>,
let const_expr = lookup_const_by_id(cx.tcx, did).unwrap();
vec!(ConstantValue(eval_const_expr(cx.tcx, &*const_expr)))
},
Some(&DefStruct(_)) => vec!(Single),
Some(&DefVariant(_, id, _)) => vec!(Variant(id)),
_ => vec!()
},
Expand Down Expand Up @@ -560,21 +551,6 @@ fn pat_constructors(cx: &MatchCheckCtxt, p: Gc<Pat>,
}
}

fn is_wild(cx: &MatchCheckCtxt, p: Gc<Pat>) -> bool {
let pat = raw_pat(p);
match pat.node {
PatWild | PatWildMulti => true,
PatIdent(_, _, _) =>
match cx.tcx.def_map.borrow().find(&pat.id) {
Some(&DefVariant(_, _, _)) | Some(&DefStatic(..)) => false,
_ => true
},
PatVec(ref before, Some(_), ref after) =>
before.is_empty() && after.is_empty(),
_ => false
}
}

/// This computes the arity of a constructor. The arity of a constructor
/// is how many subpattern patterns of that constructor should be expanded to.
///
Expand Down Expand Up @@ -780,7 +756,7 @@ pub fn specialize(cx: &MatchCheckCtxt, r: &[Gc<Pat>],
}

fn default(cx: &MatchCheckCtxt, r: &[Gc<Pat>]) -> Option<Vec<Gc<Pat>>> {
if is_wild(cx, r[0]) {
if pat_is_binding_or_wild(&cx.tcx.def_map, &*raw_pat(r[0])) {
Some(Vec::from_slice(r.tail()))
} else {
None
Expand Down Expand Up @@ -833,12 +809,14 @@ fn check_fn(cx: &mut MatchCheckCtxt,

fn is_refutable(cx: &MatchCheckCtxt, pat: Gc<Pat>) -> Option<Gc<Pat>> {
let pats = Matrix(vec!(vec!(pat)));
is_useful(cx, &pats, [wild()], ConstructWitness)
.useful()
.map(|pats| {
match is_useful(cx, &pats, [wild()], ConstructWitness) {
UsefulWithWitness(pats) => {
assert_eq!(pats.len(), 1);
pats.get(0).clone()
})
Some(pats.get(0).clone())
},
NotUseful => None,
Useful => unreachable!()
}
}

// Legality of move bindings checking
Expand Down
25 changes: 5 additions & 20 deletions src/librustc/middle/trans/_match.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -212,7 +212,6 @@ use middle::trans::cleanup::CleanupMethods;
use middle::trans::common::*;
use middle::trans::consts;
use middle::trans::controlflow;
use middle::trans::datum;
use middle::trans::datum::*;
use middle::trans::expr::Dest;
use middle::trans::expr;
Expand All @@ -236,10 +235,8 @@ use syntax::ast_util;
use syntax::codemap::Span;
use syntax::parse::token::InternedString;

// An option identifying a literal: either a unit-like struct or an
// expression.
// An option identifying a literal: either an expression or a DefId of a static expression.
enum Lit {
UnitLikeStructLit(ast::NodeId), // the node ID of the pattern
ExprLit(Gc<ast::Expr>),
ConstLit(ast::DefId), // the def ID of the constant
}
Expand All @@ -262,14 +259,12 @@ enum Opt {
fn lit_to_expr(tcx: &ty::ctxt, a: &Lit) -> Gc<ast::Expr> {
match *a {
ExprLit(existing_a_expr) => existing_a_expr,
ConstLit(a_const) => const_eval::lookup_const_by_id(tcx, a_const).unwrap(),
UnitLikeStructLit(_) => fail!("lit_to_expr: unexpected struct lit"),
ConstLit(a_const) => const_eval::lookup_const_by_id(tcx, a_const).unwrap()
}
}

fn opt_eq(tcx: &ty::ctxt, a: &Opt, b: &Opt) -> bool {
match (a, b) {
(&lit(UnitLikeStructLit(a)), &lit(UnitLikeStructLit(b))) => a == b,
(&lit(a), &lit(b)) => {
let a_expr = lit_to_expr(tcx, &a);
let b_expr = lit_to_expr(tcx, &b);
Expand Down Expand Up @@ -310,11 +305,6 @@ fn trans_opt<'a>(bcx: &'a Block<'a>, o: &Opt) -> opt_result<'a> {
let lit_datum = unpack_datum!(bcx, lit_datum.to_appropriate_datum(bcx));
return single_result(Result::new(bcx, lit_datum.val));
}
lit(UnitLikeStructLit(pat_id)) => {
let struct_ty = ty::node_id_to_type(bcx.tcx(), pat_id);
let datum = datum::rvalue_scratch_datum(bcx, struct_ty, "");
return single_result(Result::new(bcx, datum.val));
}
lit(l @ ConstLit(ref def_id)) => {
let lit_ty = ty::node_id_to_type(bcx.tcx(), lit_to_expr(bcx.tcx(), &l).id);
let (llval, _) = consts::get_const_val(bcx.ccx(), *def_id);
Expand Down Expand Up @@ -347,9 +337,6 @@ fn variant_opt(bcx: &Block, pat_id: ast::NodeId) -> Opt {
let variant = ty::enum_variant_with_id(ccx.tcx(), enum_id, var_id);
var(variant.disr_val, adt::represent_node(bcx, pat_id), var_id)
}
def::DefFn(..) | def::DefStruct(_) => {
lit(UnitLikeStructLit(pat_id))
}
_ => {
ccx.sess().bug("non-variant or struct in variant_opt()");
}
Expand Down Expand Up @@ -567,7 +554,6 @@ fn enter_opt<'a, 'b>(
let _indenter = indenter();

let ctor = match opt {
&lit(UnitLikeStructLit(_)) => check_match::Single,
&lit(x) => check_match::ConstantValue(const_eval::eval_const_expr(
bcx.tcx(), lit_to_expr(bcx.tcx(), &x))),
&range(ref lo, ref hi) => check_match::ConstantRange(
Expand Down Expand Up @@ -672,11 +658,10 @@ fn get_options(bcx: &Block, m: &[Match], col: uint) -> Vec<Opt> {
add_to_set(ccx.tcx(), &mut found, lit(ExprLit(l)));
}
ast::PatIdent(..) => {
// This is one of: an enum variant, a unit-like struct, or a
// variable binding.
// This is either an enum variant or a variable binding.
let opt_def = ccx.tcx.def_map.borrow().find_copy(&cur.id);
match opt_def {
Some(def::DefVariant(..)) | Some(def::DefStruct(..)) => {
Some(def::DefVariant(..)) => {
add_to_set(ccx.tcx(), &mut found,
variant_opt(bcx, cur.id));
}
Expand Down Expand Up @@ -827,7 +812,7 @@ fn any_irrefutable_adt_pat(bcx: &Block, m: &[Match], col: uint) -> bool {
let pat = *br.pats.get(col);
match pat.node {
ast::PatTup(_) => true,
ast::PatStruct(_, _, _) | ast::PatEnum(_, _) =>
ast::PatEnum(..) | ast::PatIdent(_, _, None) | ast::PatStruct(..) =>
match bcx.tcx().def_map.borrow().find(&pat.id) {
Some(&def::DefFn(..)) |
Some(&def::DefStruct(..)) => true,
Expand Down
22 changes: 22 additions & 0 deletions src/test/run-pass/issue-12285.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

struct S;

fn main() {
match Some(&S) {
Some(&S) => {},
_x => unreachable!()
}
match Some(&S) {
Some(&S) => {},
None => unreachable!()
}
}