Skip to content

Commit 91b27ec

Browse files
borsbors
committed
Auto merge of #30724 - nikomatsakis:feature-gate-defaulted-type-parameters, r=pnkfelix
It was recently realized that we accept defaulted type parameters everywhere, without feature gate, even though the only place that we really *intended* to accept them were on types. This PR adds a lint warning unless the "type-parameter-defaults" feature is enabled. This should eventually become a hard error. This is a [breaking-change] in that new feature gates are required (or simply removing the defaults, which is probably a better choice as they have little effect at this time). Results of a [crater run][crater] suggest that approximately 5-15 crates are affected. I didn't do the measurement quite right so that run cannot distinguish "true" regressions from "non-root" regressions, but even the upper bound of 15 affected crates seems relatively minimal. [crater]: https://gist.github.com/nikomatsakis/760c6a67698bd24253bf cc @rust-lang/lang r? @pnkfelix
2 parents 4406717 + 6dd3f61 commit 91b27ec

File tree

11 files changed

+76
-19
lines changed

11 files changed

+76
-19
lines changed

‎src/libcollections/btree/map.rs

+8-8
Original file line numberDiff line numberDiff line change
@@ -1591,10 +1591,10 @@ impl<K: Ord, V> BTreeMap<K, V> {
15911591
#[unstable(feature = "btree_range",
15921592
reason = "matches collection reform specification, waiting for dust to settle",
15931593
issue = "27787")]
1594-
pub fn range<Min: ?Sized + Ord = K, Max: ?Sized + Ord = K>(&self,
1595-
min: Bound<&Min>,
1596-
max: Bound<&Max>)
1597-
-> Range<K, V>
1594+
pub fn range<Min: ?Sized + Ord, Max: ?Sized + Ord>(&self,
1595+
min: Bound<&Min>,
1596+
max: Bound<&Max>)
1597+
-> Range<K, V>
15981598
where K: Borrow<Min> + Borrow<Max>
15991599
{
16001600
range_impl!(&self.root,
@@ -1633,10 +1633,10 @@ impl<K: Ord, V> BTreeMap<K, V> {
16331633
#[unstable(feature = "btree_range",
16341634
reason = "matches collection reform specification, waiting for dust to settle",
16351635
issue = "27787")]
1636-
pub fn range_mut<Min: ?Sized + Ord = K, Max: ?Sized + Ord = K>(&mut self,
1637-
min: Bound<&Min>,
1638-
max: Bound<&Max>)
1639-
-> RangeMut<K, V>
1636+
pub fn range_mut<Min: ?Sized + Ord, Max: ?Sized + Ord>(&mut self,
1637+
min: Bound<&Min>,
1638+
max: Bound<&Max>)
1639+
-> RangeMut<K, V>
16401640
where K: Borrow<Min> + Borrow<Max>
16411641
{
16421642
range_impl!(&mut self.root,

‎src/libcollections/btree/set.rs

+4-4
Original file line numberDiff line numberDiff line change
@@ -154,10 +154,10 @@ impl<T: Ord> BTreeSet<T> {
154154
#[unstable(feature = "btree_range",
155155
reason = "matches collection reform specification, waiting for dust to settle",
156156
issue = "27787")]
157-
pub fn range<'a, Min: ?Sized + Ord = T, Max: ?Sized + Ord = T>(&'a self,
158-
min: Bound<&Min>,
159-
max: Bound<&Max>)
160-
-> Range<'a, T>
157+
pub fn range<'a, Min: ?Sized + Ord, Max: ?Sized + Ord>(&'a self,
158+
min: Bound<&Min>,
159+
max: Bound<&Max>)
160+
-> Range<'a, T>
161161
where T: Borrow<Min> + Borrow<Max>
162162
{
163163
fn first<A, B>((a, _): (A, B)) -> A {

‎src/libcore/iter.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -2132,7 +2132,7 @@ pub trait Iterator {
21322132
/// ```
21332133
#[unstable(feature = "iter_arith", reason = "bounds recently changed",
21342134
issue = "27739")]
2135-
fn sum<S=<Self as Iterator>::Item>(self) -> S where
2135+
fn sum<S>(self) -> S where
21362136
S: Add<Self::Item, Output=S> + Zero,
21372137
Self: Sized,
21382138
{
@@ -2157,7 +2157,7 @@ pub trait Iterator {
21572157
/// ```
21582158
#[unstable(feature="iter_arith", reason = "bounds recently changed",
21592159
issue = "27739")]
2160-
fn product<P=<Self as Iterator>::Item>(self) -> P where
2160+
fn product<P>(self) -> P where
21612161
P: Mul<Self::Item, Output=P> + One,
21622162
Self: Sized,
21632163
{

‎src/librustc/lint/builtin.rs

+10
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,9 @@
1616
1717
use lint::{LintPass, LateLintPass, LintArray};
1818

19+
// name of the future-incompatible group
20+
pub const FUTURE_INCOMPATIBLE: &'static str = "future_incompatible";
21+
1922
declare_lint! {
2023
pub CONST_ERR,
2124
Warn,
@@ -124,6 +127,12 @@ declare_lint! {
124127
"detect private items in public interfaces not caught by the old implementation"
125128
}
126129

130+
declare_lint! {
131+
pub INVALID_TYPE_PARAM_DEFAULT,
132+
Warn,
133+
"type parameter default erroneously allowed in invalid location"
134+
}
135+
127136
/// Does nothing as a lint pass, but registers some `Lint`s
128137
/// which are used by other parts of the compiler.
129138
#[derive(Copy, Clone)]
@@ -149,6 +158,7 @@ impl LintPass for HardwiredLints {
149158
TRIVIAL_CASTS,
150159
TRIVIAL_NUMERIC_CASTS,
151160
PRIVATE_IN_PUBLIC,
161+
INVALID_TYPE_PARAM_DEFAULT,
152162
CONST_ERR
153163
)
154164
}

‎src/librustc/lint/context.rs

+17-3
Original file line numberDiff line numberDiff line change
@@ -365,14 +365,16 @@ pub fn gather_attrs(attrs: &[ast::Attribute])
365365
/// lints elsewhere in the compiler should call
366366
/// `Session::add_lint()` instead.
367367
pub fn raw_emit_lint(sess: &Session,
368+
lints: &LintStore,
368369
lint: &'static Lint,
369370
lvlsrc: LevelSource,
370371
span: Option<Span>,
371372
msg: &str) {
372-
raw_struct_lint(sess, lint, lvlsrc, span, msg).emit();
373+
raw_struct_lint(sess, lints, lint, lvlsrc, span, msg).emit();
373374
}
374375

375376
pub fn raw_struct_lint<'a>(sess: &'a Session,
377+
lints: &LintStore,
376378
lint: &'static Lint,
377379
lvlsrc: LevelSource,
378380
span: Option<Span>,
@@ -414,6 +416,18 @@ pub fn raw_struct_lint<'a>(sess: &'a Session,
414416
_ => sess.bug("impossible level in raw_emit_lint"),
415417
};
416418

419+
// Check for future incompatibility lints and issue a stronger warning.
420+
let future_incompat_lints = &lints.lint_groups[builtin::FUTURE_INCOMPATIBLE];
421+
let this_id = LintId::of(lint);
422+
if future_incompat_lints.0.iter().any(|&id| id == this_id) {
423+
let msg = "this lint will become a HARD ERROR in a future release!";
424+
if let Some(sp) = span {
425+
err.span_note(sp, msg);
426+
} else {
427+
err.note(msg);
428+
}
429+
}
430+
417431
if let Some(span) = def {
418432
err.span_note(span, "lint level defined here");
419433
}
@@ -451,7 +465,7 @@ pub trait LintContext: Sized {
451465
Some(pair) => pair,
452466
};
453467

454-
raw_emit_lint(&self.sess(), lint, (level, src), span, msg);
468+
raw_emit_lint(&self.sess(), self.lints(), lint, (level, src), span, msg);
455469
}
456470

457471
fn lookup(&self,
@@ -464,7 +478,7 @@ pub trait LintContext: Sized {
464478
Some(pair) => pair,
465479
};
466480

467-
raw_struct_lint(&self.sess(), lint, (level, src), span, msg)
481+
raw_struct_lint(&self.sess(), self.lints(), lint, (level, src), span, msg)
468482
}
469483

470484
/// Emit a lint at the appropriate level, for a particular span.

‎src/librustc_lint/lib.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -143,8 +143,8 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
143143
UNUSED_MUT, UNREACHABLE_CODE, UNUSED_MUST_USE,
144144
UNUSED_UNSAFE, PATH_STATEMENTS, UNUSED_ATTRIBUTES);
145145

146-
add_lint_group!(sess, "future_incompatible",
147-
PRIVATE_IN_PUBLIC);
146+
add_lint_group!(sess, FUTURE_INCOMPATIBLE,
147+
PRIVATE_IN_PUBLIC, INVALID_TYPE_PARAM_DEFAULT);
148148

149149
// We have one lint pass defined specially
150150
store.register_late_pass(sess, false, box lint::GatherNodeLevels);

‎src/librustc_trans/trans/base.rs

+1
Original file line numberDiff line numberDiff line change
@@ -2216,6 +2216,7 @@ fn enum_variant_size_lint(ccx: &CrateContext, enum_def: &hir::EnumDef, sp: Span,
22162216
// Use lint::raw_emit_lint rather than sess.add_lint because the lint-printing
22172217
// pass for the latter already ran.
22182218
lint::raw_struct_lint(&ccx.tcx().sess,
2219+
&ccx.tcx().sess.lint_store.borrow(),
22192220
lint::builtin::VARIANT_SIZE_DIFFERENCES,
22202221
*lvlsrc.unwrap(),
22212222
Some(sp),

‎src/librustc_typeck/collect.rs

+12
Original file line numberDiff line numberDiff line change
@@ -59,6 +59,7 @@ There are some shortcomings in this design:
5959
*/
6060

6161
use astconv::{self, AstConv, ty_of_arg, ast_ty_to_ty, ast_region_to_region};
62+
use lint;
6263
use middle::def;
6364
use middle::def_id::DefId;
6465
use constrained_type_params as ctp;
@@ -1910,6 +1911,17 @@ fn get_or_create_type_parameter_def<'a,'tcx>(ccx: &CrateCtxt<'a,'tcx>,
19101911

19111912
let parent = tcx.map.get_parent(param.id);
19121913

1914+
if space != TypeSpace && default.is_some() {
1915+
if !tcx.sess.features.borrow().default_type_parameter_fallback {
1916+
tcx.sess.add_lint(
1917+
lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
1918+
param.id,
1919+
param.span,
1920+
format!("defaults for type parameters are only allowed \
1921+
on `struct` or `enum` definitions (see issue #27336)"));
1922+
}
1923+
}
1924+
19131925
let def = ty::TypeParameterDef {
19141926
space: space,
19151927
index: index,

‎src/test/auxiliary/default_ty_param_cross_crate_crate.rs

+1
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,7 @@
1010

1111
#![crate_type = "lib"]
1212
#![crate_name = "default_param_test"]
13+
#![feature(default_type_parameter_fallback)]
1314

1415
use std::marker::PhantomData;
1516

‎src/test/compile-fail/issue-26812.rs

+2
Original file line numberDiff line numberDiff line change
@@ -8,5 +8,7 @@
88
// option. This file may not be copied, modified, or distributed
99
// except according to those terms.
1010

11+
#![feature(default_type_parameter_fallback)]
12+
1113
fn avg<T=T::Item>(_: T) {} //~ ERROR associated type `Item` not found for `T`
1214
fn main() {}

‎src/test/compile-fail/type-parameter-invalid-lint.rs

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
1+
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2+
// file at the top-level directory of this distribution and at
3+
// http://rust-lang.org/COPYRIGHT.
4+
//
5+
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+
// option. This file may not be copied, modified, or distributed
9+
// except according to those terms.
10+
11+
#![deny(future_incompatible)]
12+
#![allow(dead_code)]
13+
14+
fn avg<T=i32>(_: T) {}
15+
//~^ ERROR defaults for type parameters are only allowed
16+
//~| NOTE HARD ERROR
17+
fn main() {}

0 commit comments

Comments
 (0)