2018-05-23 04:56:02 +00:00
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//! lint on indexing and slicing operations
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2021-06-03 06:41:37 +00:00
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use clippy_utils::consts::{constant, Constant};
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2021-03-25 18:29:11 +00:00
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use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
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use clippy_utils::higher;
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2020-03-01 03:23:33 +00:00
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use rustc_ast::ast::RangeLimits;
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2020-02-21 08:39:38 +00:00
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use rustc_hir::{Expr, ExprKind};
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2020-01-12 06:08:41 +00:00
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use rustc_lint::{LateContext, LateLintPass};
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2020-03-30 09:02:14 +00:00
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use rustc_middle::ty;
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2020-01-11 11:37:08 +00:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2015-12-21 18:22:29 +00:00
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2021-07-29 10:16:06 +00:00
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/// ### What it does
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/// Checks for out of bounds array indexing with a constant
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2019-03-05 16:50:33 +00:00
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/// index.
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///
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2021-07-29 10:16:06 +00:00
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/// ### Why is this bad?
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/// This will always panic at runtime.
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2019-03-05 16:50:33 +00:00
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///
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2021-07-29 10:16:06 +00:00
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/// ### Example
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2022-06-05 19:24:41 +00:00
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/// ```rust,no_run
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2019-03-05 22:23:50 +00:00
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/// # #![allow(const_err)]
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2019-03-05 16:50:33 +00:00
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/// let x = [1, 2, 3, 4];
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///
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/// x[9];
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/// &x[2..9];
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2022-06-05 19:24:41 +00:00
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/// ```
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///
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/// Use instead:
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/// ```rust
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/// # let x = [1, 2, 3, 4];
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/// // Index within bounds
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2019-03-05 16:50:33 +00:00
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///
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/// x[0];
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/// x[3];
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/// ```
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Added `clippy::version` attribute to all normal lints
So, some context for this, well, more a story. I'm not used to scripting, I've never really scripted anything, even if it's a valuable skill. I just never really needed it. Now, `@flip1995` correctly suggested using a script for this in `rust-clippy#7813`...
And I decided to write a script using nushell because why not? This was a mistake... I spend way more time on this than I would like to admit. It has definitely been more than 4 hours. It shouldn't take that long, but me being new to scripting and nushell just wasn't a good mixture... Anyway, here is the script that creates another script which adds the versions. Fun...
Just execute this on the `gh-pages` branch and the resulting `replacer.sh` in `clippy_lints` and it should all work.
```nu
mv v0.0.212 rust-1.00.0;
mv beta rust-1.57.0;
mv master rust-1.58.0;
let paths = (open ./rust-1.58.0/lints.json | select id id_span | flatten | select id path);
let versions = (
ls | where name =~ "rust-" | select name | format {name}/lints.json |
each { open $it | select id | insert version $it | str substring "5,11" version} |
group-by id | rotate counter-clockwise id version |
update version {get version | first 1} | flatten | select id version);
$paths | each { |row|
let version = ($versions | where id == ($row.id) | format {version})
let idu = ($row.id | str upcase)
$"sed -i '0,/($idu),/{s/pub ($idu),/#[clippy::version = "($version)"]\n pub ($idu),/}' ($row.path)"
} | str collect ";" | str find-replace --all '1.00.0' 'pre 1.29.0' | save "replacer.sh";
```
And this still has some problems, but at this point I just want to be done -.-
2021-10-21 19:06:26 +00:00
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#[clippy::version = "pre 1.29.0"]
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2015-12-21 18:22:29 +00:00
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pub OUT_OF_BOUNDS_INDEXING,
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2018-03-28 13:24:26 +00:00
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correctness,
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2016-08-06 08:18:36 +00:00
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"out of bounds constant indexing"
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2015-12-21 18:22:29 +00:00
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}
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2021-07-29 10:16:06 +00:00
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/// ### What it does
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/// Checks for usage of indexing or slicing. Arrays are special cases, this lint
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2019-03-05 16:50:33 +00:00
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/// does report on arrays if we can tell that slicing operations are in bounds and does not
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/// lint on constant `usize` indexing on arrays because that is handled by rustc's `const_err` lint.
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///
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2021-07-29 10:16:06 +00:00
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/// ### Why is this bad?
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/// Indexing and slicing can panic at runtime and there are
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2019-03-05 16:50:33 +00:00
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/// safe alternatives.
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///
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2021-07-29 10:16:06 +00:00
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/// ### Example
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2019-08-03 19:24:50 +00:00
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/// ```rust,no_run
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2019-03-05 16:50:33 +00:00
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/// // Vector
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/// let x = vec![0; 5];
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///
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/// x[2];
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/// &x[2..100];
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///
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/// // Array
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/// let y = [0, 1, 2, 3];
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///
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/// &y[10..100];
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/// &y[10..];
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2022-06-05 19:24:41 +00:00
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/// ```
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///
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/// Use instead:
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/// ```rust
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2022-06-07 00:28:16 +00:00
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/// # #![allow(unused)]
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///
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2022-06-05 19:24:41 +00:00
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/// # let x = vec![0; 5];
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/// # let y = [0, 1, 2, 3];
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/// x.get(2);
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/// x.get(2..100);
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2019-03-05 16:50:33 +00:00
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///
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/// y.get(10);
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/// y.get(10..100);
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/// ```
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Added `clippy::version` attribute to all normal lints
So, some context for this, well, more a story. I'm not used to scripting, I've never really scripted anything, even if it's a valuable skill. I just never really needed it. Now, `@flip1995` correctly suggested using a script for this in `rust-clippy#7813`...
And I decided to write a script using nushell because why not? This was a mistake... I spend way more time on this than I would like to admit. It has definitely been more than 4 hours. It shouldn't take that long, but me being new to scripting and nushell just wasn't a good mixture... Anyway, here is the script that creates another script which adds the versions. Fun...
Just execute this on the `gh-pages` branch and the resulting `replacer.sh` in `clippy_lints` and it should all work.
```nu
mv v0.0.212 rust-1.00.0;
mv beta rust-1.57.0;
mv master rust-1.58.0;
let paths = (open ./rust-1.58.0/lints.json | select id id_span | flatten | select id path);
let versions = (
ls | where name =~ "rust-" | select name | format {name}/lints.json |
each { open $it | select id | insert version $it | str substring "5,11" version} |
group-by id | rotate counter-clockwise id version |
update version {get version | first 1} | flatten | select id version);
$paths | each { |row|
let version = ($versions | where id == ($row.id) | format {version})
let idu = ($row.id | str upcase)
$"sed -i '0,/($idu),/{s/pub ($idu),/#[clippy::version = "($version)"]\n pub ($idu),/}' ($row.path)"
} | str collect ";" | str find-replace --all '1.00.0' 'pre 1.29.0' | save "replacer.sh";
```
And this still has some problems, but at this point I just want to be done -.-
2021-10-21 19:06:26 +00:00
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#[clippy::version = "pre 1.29.0"]
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2016-03-11 09:51:16 +00:00
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pub INDEXING_SLICING,
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2018-08-02 17:06:03 +00:00
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restriction,
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2016-03-11 09:51:16 +00:00
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"indexing/slicing usage"
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}
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(IndexingSlicing => [INDEXING_SLICING, OUT_OF_BOUNDS_INDEXING]);
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2015-12-21 18:22:29 +00:00
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2020-06-25 20:41:36 +00:00
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impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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2022-03-26 05:05:38 +00:00
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if cx.tcx.hir().is_inside_const_context(expr.hir_id) {
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return;
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}
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2021-04-08 15:50:13 +00:00
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if let ExprKind::Index(array, index) = &expr.kind {
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2020-09-24 12:49:22 +00:00
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let ty = cx.typeck_results().expr_ty(array).peel_refs();
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2021-08-08 14:49:13 +00:00
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if let Some(range) = higher::Range::hir(index) {
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2019-01-31 01:15:29 +00:00
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// Ranged indexes, i.e., &x[n..m], &x[n..], &x[..n] and &x[..]
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2020-08-03 22:18:29 +00:00
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if let ty::Array(_, s) = ty.kind() {
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2020-03-02 20:53:41 +00:00
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let size: u128 = if let Some(size) = s.try_eval_usize(cx.tcx, cx.param_env) {
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size.into()
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} else {
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return;
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};
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2018-10-13 20:51:53 +00:00
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2018-10-14 14:49:28 +00:00
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let const_range = to_const_range(cx, range, size);
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if let (Some(start), _) = const_range {
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if start > size {
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2020-02-18 13:28:18 +00:00
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span_lint(
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2018-10-14 14:49:28 +00:00
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cx,
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OUT_OF_BOUNDS_INDEXING,
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2018-10-15 11:44:39 +00:00
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range.start.map_or(expr.span, |start| start.span),
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2018-10-14 14:49:28 +00:00
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"range is out of bounds",
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);
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2018-10-13 20:51:53 +00:00
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return;
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2018-10-14 14:49:28 +00:00
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}
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}
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if let (_, Some(end)) = const_range {
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if end > size {
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2020-02-18 13:28:18 +00:00
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span_lint(
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2018-10-14 14:49:28 +00:00
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cx,
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OUT_OF_BOUNDS_INDEXING,
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2018-10-15 11:44:39 +00:00
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range.end.map_or(expr.span, |end| end.span),
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2018-10-14 14:49:28 +00:00
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"range is out of bounds",
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);
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return;
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}
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}
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if let (Some(_), Some(_)) = const_range {
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// early return because both start and end are constants
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// and we have proven above that they are in bounds
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return;
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2017-09-13 13:34:04 +00:00
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}
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2015-12-21 18:22:29 +00:00
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}
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2018-06-14 20:04:37 +00:00
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let help_msg = match (range.start, range.end) {
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2021-03-12 14:30:50 +00:00
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(None, Some(_)) => "consider using `.get(..n)`or `.get_mut(..n)` instead",
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(Some(_), None) => "consider using `.get(n..)` or .get_mut(n..)` instead",
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(Some(_), Some(_)) => "consider using `.get(n..m)` or `.get_mut(n..m)` instead",
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2018-06-14 20:04:37 +00:00
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(None, None) => return, // [..] is ok.
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};
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2021-03-12 14:30:50 +00:00
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span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic", None, help_msg);
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2018-06-14 20:04:37 +00:00
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} else {
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2019-01-31 01:15:29 +00:00
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// Catchall non-range index, i.e., [n] or [n << m]
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2020-08-03 22:18:29 +00:00
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if let ty::Array(..) = ty.kind() {
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2022-03-26 05:05:38 +00:00
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// Index is a const block.
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if let ExprKind::ConstBlock(..) = index.kind {
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return;
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}
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2018-06-14 20:04:37 +00:00
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// Index is a constant uint.
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2020-07-17 08:47:04 +00:00
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if let Some(..) = constant(cx, cx.typeck_results(), index) {
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2018-06-19 21:30:43 +00:00
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// Let rustc's `const_err` lint handle constant `usize` indexing on arrays.
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2018-06-14 20:04:37 +00:00
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return;
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2016-03-11 09:51:16 +00:00
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}
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}
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2018-06-14 20:04:37 +00:00
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2020-02-18 13:28:18 +00:00
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span_lint_and_help(
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2018-06-14 20:04:37 +00:00
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cx,
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INDEXING_SLICING,
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expr.span,
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2021-03-12 14:30:50 +00:00
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"indexing may panic",
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2020-04-18 10:28:29 +00:00
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None,
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2021-03-12 14:30:50 +00:00
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"consider using `.get(n)` or `.get_mut(n)` instead",
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2018-06-14 20:04:37 +00:00
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);
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2015-12-21 18:22:29 +00:00
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}
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}
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}
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}
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2016-03-11 09:51:16 +00:00
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2018-10-13 20:51:53 +00:00
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/// Returns a tuple of options with the start and end (exclusive) values of
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/// the range. If the start or end is not constant, None is returned.
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2020-06-25 20:41:36 +00:00
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fn to_const_range<'tcx>(
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cx: &LateContext<'tcx>,
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2020-02-18 13:28:18 +00:00
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range: higher::Range<'_>,
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2018-05-23 04:56:02 +00:00
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array_size: u128,
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2018-10-13 20:51:53 +00:00
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) -> (Option<u128>, Option<u128>) {
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2020-07-17 08:47:04 +00:00
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let s = range
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.start
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.map(|expr| constant(cx, cx.typeck_results(), expr).map(|(c, _)| c));
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2018-04-02 04:34:11 +00:00
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let start = match s {
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2018-10-13 20:51:53 +00:00
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Some(Some(Constant::Int(x))) => Some(x),
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Some(_) => None,
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None => Some(0),
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2016-03-11 09:51:16 +00:00
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};
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2020-07-17 08:47:04 +00:00
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let e = range
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.end
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.map(|expr| constant(cx, cx.typeck_results(), expr).map(|(c, _)| c));
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2018-04-02 04:34:11 +00:00
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let end = match e {
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2018-11-27 20:14:15 +00:00
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Some(Some(Constant::Int(x))) => {
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if range.limits == RangeLimits::Closed {
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Some(x + 1)
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} else {
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Some(x)
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}
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2016-12-20 17:21:30 +00:00
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},
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2018-10-13 20:51:53 +00:00
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Some(_) => None,
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None => Some(array_size),
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2016-03-11 09:51:16 +00:00
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};
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2018-10-13 20:51:53 +00:00
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(start, end)
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2016-03-11 09:51:16 +00:00
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}
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