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Revert "Add lint checks for unused loop labels"

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This functionality is being reimplemented in the resolver phase

This reverts commit 503a69e844970476b27bf1ac7be951bb22194f50.
This commit is contained in:
Kyle Stachowicz 2018-05-17 16:57:46 -07:00
parent 167cedefe6
commit 7676982e90
5 changed files with 1 additions and 190 deletions
src
librustc_lint
lib.rsunused.rs
librustc_mir/interpret
eval_context.rs
test/ui/lint
unused_label.rsunused_label.stderr

2
src/librustc_lint/lib.rs

@ -110,7 +110,6 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
add_early_builtin_with_new!(sess,
DeprecatedAttr,
UnusedLabel,
);
add_builtin!(sess,
@ -178,7 +177,6 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
UNUSED_DOC_COMMENT,
UNUSED_EXTERN_CRATES,
UNUSED_FEATURES,
UNUSED_LABEL,
UNUSED_PARENS);
add_lint_group!(sess,

58
src/librustc_lint/unused.rs

@ -464,61 +464,3 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAllocation {
}
}
}
declare_lint! {
pub(super) UNUSED_LABEL,
Warn,
"warns on unused labels"
}
#[derive(Clone)]
pub struct UnusedLabel(pub Vec<(ast::Label, bool)>);
impl UnusedLabel {
pub fn new() -> Self {
UnusedLabel(vec![])
}
}
impl LintPass for UnusedLabel {
fn get_lints(&self) -> LintArray {
lint_array!(UNUSED_LABEL)
}
}
impl EarlyLintPass for UnusedLabel {
fn check_expr(&mut self, _: &EarlyContext, expr: &ast::Expr) {
match expr.node {
ast::ExprKind::While(_, _, Some(label))
| ast::ExprKind::WhileLet(_, _, _, Some(label))
| ast::ExprKind::ForLoop(_, _, _, Some(label))
| ast::ExprKind::Loop(_, Some(label)) => {
self.0.push((label, false));
}
ast::ExprKind::Break(Some(label), _) | ast::ExprKind::Continue(Some(label)) => {
if let Some((_, ref mut was_used)) =
self.0.iter_mut().rev().find(|(l, _)| label == *l)
{
*was_used = true;
}
}
_ => {}
}
}
fn check_expr_post(&mut self, ctxt: &EarlyContext, expr: &ast::Expr) {
match expr.node {
ast::ExprKind::While(_, _, Some(label))
| ast::ExprKind::WhileLet(_, _, _, Some(label))
| ast::ExprKind::ForLoop(_, _, _, Some(label))
| ast::ExprKind::Loop(_, Some(label)) => {
if let Some((_, was_used)) = self.0.pop() {
if !was_used {
ctxt.span_lint(UNUSED_LABEL, label.ident.span, "unused label");
}
}
}
_ => {}
}
}
}

2
src/librustc_mir/interpret/eval_context.rs

@ -1705,7 +1705,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M
let mut trace_text = "\n\nAn error occurred in miri:\n".to_string();
backtrace.resolve();
write!(trace_text, "backtrace frames: {}\n", backtrace.frames().len()).unwrap();
for (i, frame) in backtrace.frames().iter().enumerate() {
'frames: for (i, frame) in backtrace.frames().iter().enumerate() {
if frame.symbols().is_empty() {
write!(trace_text, "{}: no symbols\n", i).unwrap();
}

76
src/test/ui/lint/unused_label.rs

@ -1,76 +0,0 @@
// Copyright 2017 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.
// The output should warn when a loop label is not used. However, it
// should also deal with the edge cases where a label is shadowed,
// within nested loops
// compile-pass
// compile-flags: -W unused-label
fn main() {
'unused_while_label: while 0 == 0 {
//~^ WARN unused label
}
let opt = Some(0);
'unused_while_let_label: while let Some(_) = opt {
//~^ WARN unused label
}
'unused_for_label: for _ in 0..10 {
//~^ WARN unused label
}
'used_loop_label: loop {
break 'used_loop_label;
}
'used_loop_label_outer_1: for _ in 0..10 {
'used_loop_label_inner_1: for _ in 0..10 {
break 'used_loop_label_inner_1;
}
break 'used_loop_label_outer_1;
}
'used_loop_label_outer_2: for _ in 0..10 {
'unused_loop_label_inner_2: for _ in 0..10 {
//~^ WARN unused label
break 'used_loop_label_outer_2;
}
}
'unused_loop_label_outer_3: for _ in 0..10 {
//~^ WARN unused label
'used_loop_label_inner_3: for _ in 0..10 {
break 'used_loop_label_inner_3;
}
}
// Test breaking many times with the same inner label doesn't break the
// warning on the outer label
'many_used_shadowed: for _ in 0..10 {
//~^ WARN unused label
'many_used_shadowed: for _ in 0..10 {
//~^ WARN label name `'many_used_shadowed` shadows a label name that is already in scope
if 1 % 2 == 0 {
break 'many_used_shadowed;
} else {
break 'many_used_shadowed;
}
}
}
// This is diverging, so put it at the end so we don't get
// unreachable_code errors everywhere else
'unused_loop_label: loop {
//~^ WARN unused label
}
}

53
src/test/ui/lint/unused_label.stderr

@ -1,53 +0,0 @@
warning: unused label
--> $DIR/unused_label.rs:19:5
|
LL | 'unused_while_label: while 0 == 0 {
| ^^^^^^^^^^^^^^^^^^^
|
= note: requested on the command line with `-W unused-label`
warning: unused label
--> $DIR/unused_label.rs:24:5
|
LL | 'unused_while_let_label: while let Some(_) = opt {
| ^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_label.rs:28:5
|
LL | 'unused_for_label: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_label.rs:44:9
|
LL | 'unused_loop_label_inner_2: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_label.rs:50:5
|
LL | 'unused_loop_label_outer_3: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_label.rs:59:5
|
LL | 'many_used_shadowed: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^
warning: unused label
--> $DIR/unused_label.rs:73:5
|
LL | 'unused_loop_label: loop {
| ^^^^^^^^^^^^^^^^^^
warning: label name `'many_used_shadowed` shadows a label name that is already in scope
--> $DIR/unused_label.rs:61:9
|
LL | 'many_used_shadowed: for _ in 0..10 {
| ------------------- first declared here
LL | //~^ WARN unused label
LL | 'many_used_shadowed: for _ in 0..10 {
| ^^^^^^^^^^^^^^^^^^^ lifetime 'many_used_shadowed already in scope