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Restrict constants in patterns #32199

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merged 10 commits into from
Mar 26, 2016
+438 −46
Merged

Restrict constants in patterns #32199

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5bc2868
make `const_expr_to_pat` fallible (but never have it actually fail)
nikomatsakis Feb 3, 2016
99c2a6b
modify #[deriving(Eq)] to emit #[structural_match]
nikomatsakis Mar 11, 2016
05baf64
do not overwrite spans as eagerly
nikomatsakis Mar 11, 2016
f69eb8e
issue a future-compat lint for constants of invalid type
nikomatsakis Mar 11, 2016
73b4f06
suppress duplicate lints
nikomatsakis Mar 11, 2016
56ebf2b
fallout in existing tests
nikomatsakis Mar 11, 2016
7f661ec
new tests for RFC #1445
nikomatsakis Mar 11, 2016
93e4443
check for both partialeq and eq
nikomatsakis Mar 25, 2016
944dc4a
fix cargo.toml for new dependency
nikomatsakis Mar 25, 2016
2536ae5
fix error message
nikomatsakis Mar 25, 2016
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make const_expr_to_pat fallible (but never have it actually fail)
@nikomatsakis
nikomatsakis committed Mar 25, 2016
commit 5bc286806023ef4d63bceec4ba703399ba9ee2f7
26 changes: 18 additions & 8 deletions src/librustc/middle/check_match.rs
View file
Original file line number Diff line number Diff line change
@@ -478,15 +478,25 @@ impl<'a, 'tcx> Folder for StaticInliner<'a, 'tcx> {
Some(Def::Const(did)) => {
let substs = Some(self.tcx.node_id_item_substs(pat.id).substs);
if let Some((const_expr, _)) = lookup_const_by_id(self.tcx, did, substs) {
const_expr_to_pat(self.tcx, const_expr, pat.span).map(|new_pat| {

if let Some(ref mut renaming_map) = self.renaming_map {
// Record any renamings we do here
record_renamings(const_expr, &pat, renaming_map);
match const_expr_to_pat(self.tcx, const_expr, pat.span) {
Ok(new_pat) => {
if let Some(ref mut map) = self.renaming_map {
// Record any renamings we do here
record_renamings(const_expr, &pat, map);
}
new_pat
}

new_pat
})
Err(def_id) => {
// TODO back-compat
self.failed = true;
self.tcx.sess.span_err(
pat.span,
&format!("constants of the type `{}` \
cannot be used in patterns",
self.tcx.item_path_str(def_id)));
pat
}
}
} else {
self.failed = true;
span_err!(self.tcx.sess, pat.span, E0158,
40 changes: 25 additions & 15 deletions src/librustc/middle/const_eval.rs
View file
Original file line number Diff line number Diff line change
@@ -323,10 +323,13 @@ impl ConstVal {
}
}

pub fn const_expr_to_pat(tcx: &TyCtxt, expr: &Expr, span: Span) -> P<hir::Pat> {
pub fn const_expr_to_pat(tcx: &ty::TyCtxt, expr: &Expr, span: Span)
-> Result<P<hir::Pat>, DefId> {
let pat = match expr.node {
hir::ExprTup(ref exprs) =>
PatKind::Tup(exprs.iter().map(|expr| const_expr_to_pat(tcx, &expr, span)).collect()),
PatKind::Tup(try!(exprs.iter()
.map(|expr| const_expr_to_pat(tcx, &expr, span))
.collect())),

hir::ExprCall(ref callee, ref args) => {
let def = *tcx.def_map.borrow().get(&callee.id).unwrap();
@@ -336,31 +339,38 @@ pub fn const_expr_to_pat(tcx: &TyCtxt, expr: &Expr, span: Span) -> P<hir::Pat> {
let path = match def.full_def() {
Def::Struct(def_id) => def_to_path(tcx, def_id),
Def::Variant(_, variant_did) => def_to_path(tcx, variant_did),
Def::Fn(..) => return P(hir::Pat {
Def::Fn(..) => return Ok(P(hir::Pat {
id: expr.id,
node: PatKind::Lit(P(expr.clone())),
span: span,
}),
})),
_ => unreachable!()
};
let pats = args.iter().map(|expr| const_expr_to_pat(tcx, &expr, span)).collect();
let pats = try!(args.iter()
.map(|expr| const_expr_to_pat(tcx, &**expr, span))
.collect());
PatKind::TupleStruct(path, Some(pats))
}

hir::ExprStruct(ref path, ref fields, None) => {
let field_pats = fields.iter().map(|field| codemap::Spanned {
span: codemap::DUMMY_SP,
node: hir::FieldPat {
name: field.name.node,
pat: const_expr_to_pat(tcx, &field.expr, span),
is_shorthand: false,
},
}).collect();
let field_pats =
try!(fields.iter()
.map(|field| Ok(codemap::Spanned {
span: codemap::DUMMY_SP,
node: hir::FieldPat {
name: field.name.node,
pat: try!(const_expr_to_pat(tcx, &field.expr, span)),
is_shorthand: false,
},
}))
.collect());
PatKind::Struct(path.clone(), field_pats, false)
}

hir::ExprVec(ref exprs) => {
let pats = exprs.iter().map(|expr| const_expr_to_pat(tcx, &expr, span)).collect();
let pats = try!(exprs.iter()
.map(|expr| const_expr_to_pat(tcx, &expr, span))
.collect());
PatKind::Vec(pats, None, hir::HirVec::new())
}

@@ -381,7 +391,7 @@ pub fn const_expr_to_pat(tcx: &TyCtxt, expr: &Expr, span: Span) -> P<hir::Pat> {

_ => PatKind::Lit(P(expr.clone()))
};
P(hir::Pat { id: expr.id, node: pat, span: span })
Ok(P(hir::Pat { id: expr.id, node: pat, span: span }))
}

pub fn eval_const_expr(tcx: &TyCtxt, e: &Expr) -> ConstVal {
12 changes: 9 additions & 3 deletions src/librustc_mir/hair/cx/pattern.rs
View file
Original file line number Diff line number Diff line change
@@ -90,9 +90,15 @@ impl<'patcx, 'cx, 'tcx> PatCx<'patcx, 'cx, 'tcx> {
let substs = Some(self.cx.tcx.node_id_item_substs(pat.id).substs);
match const_eval::lookup_const_by_id(self.cx.tcx, def_id, substs) {
Some((const_expr, _const_ty)) => {
let pat = const_eval::const_expr_to_pat(self.cx.tcx, const_expr,
pat.span);
return self.to_pattern(&pat);
match const_eval::const_expr_to_pat(self.cx.tcx,
const_expr,
pat.span) {
Ok(pat) =>
return self.to_pattern(&pat),
Err(_) =>
self.cx.tcx.sess.span_bug(
pat.span, "illegal constant"),
}
}
None => {
self.cx.tcx.sess.span_bug(