From 4ec439bef0124a01dd71ea0d5f441066690f33ec Mon Sep 17 00:00:00 2001
From: Shea Newton <shnewto@gmail.com>
Date: Thu, 14 Jun 2018 20:04:37 +0000
Subject: [PATCH] Revisiting indexing_slicing test cases
This commit contains a few changes. In an attempt to clarify which test cases should and should not produce stderr it became clear that some cases were being handled incorrectly. In order to address these test cases, a minor re-factor was made to the linting logic itself.
The re-factor was driven by edge case handling including a need for additional match conditions for `ExprCall` (`&x[0..=4]`) and `ExprBinary` (`x[1 << 3]`). Rather than attempt to account for each potential `Expr*` the code was re-factored into simply "if ranged index" and an "otherwise" conditions.
---
clippy_lints/src/indexing_slicing.rs | 133 ++++++---------
tests/ui/indexing_slicing.rs | 52 +++---
tests/ui/indexing_slicing.stderr | 240 +++++++++++++++++----------
3 files changed, 239 insertions(+), 186 deletions(-)
diff --git a/clippy_lints/src/indexing_slicing.rs b/clippy_lints/src/indexing_slicing.rs
index 01f9f45c589..b4e6414195e 100644
--- a/clippy_lints/src/indexing_slicing.rs
+++ b/clippy_lints/src/indexing_slicing.rs
@@ -1,8 +1,9 @@
//! lint on indexing and slicing operations
use crate::consts::{constant, Constant};
+use crate::utils;
+use crate::utils::higher;
use crate::utils::higher::Range;
-use crate::utils::{self, higher};
use rustc::hir::*;
use rustc::lint::*;
use rustc::ty;
@@ -97,89 +98,65 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if let ExprIndex(ref array, ref index) = &expr.node {
let ty = cx.tables.expr_ty(array);
- match &index.node {
- // Both ExprStruct and ExprPath require this approach's checks
- // on the `range` returned by `higher::range(cx, index)`.
- // ExprStruct handles &x[n..m], &x[n..] and &x[..n].
- // ExprPath handles &x[..] and x[var]
- ExprStruct(..) | ExprPath(..) => {
- if let Some(range) = higher::range(cx, index) {
- if let ty::TyArray(_, s) = ty.sty {
- let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
- // Index is a constant range.
- if let Some((start, end)) = to_const_range(cx, range, size) {
- if start > size || end > size {
- utils::span_lint(
- cx,
- OUT_OF_BOUNDS_INDEXING,
- expr.span,
- "range is out of bounds",
- );
- } // Else range is in bounds, ok.
-
- return;
- }
+ if let Some(range) = higher::range(cx, index) {
+ // Ranged indexes, i.e. &x[n..m], &x[n..], &x[..n] and &x[..]
+ if let ty::TyArray(_, s) = ty.sty {
+ let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
+ // Index is a constant range.
+ if let Some((start, end)) = to_const_range(cx, range, size) {
+ if start > size || end > size {
+ utils::span_lint(
+ cx,
+ OUT_OF_BOUNDS_INDEXING,
+ expr.span,
+ "range is out of bounds",
+ );
}
-
- let help_msg = match (range.start, range.end) {
- (None, Some(_)) => {
- "Consider using `.get(..n)`or `.get_mut(..n)` instead"
- }
- (Some(_), None) => {
- "Consider using `.get(n..)` or .get_mut(n..)` instead"
- }
- (Some(_), Some(_)) => {
- "Consider using `.get(n..m)` or `.get_mut(n..m)` instead"
- }
- (None, None) => return, // [..] is ok.
- };
-
- utils::span_help_and_lint(
- cx,
- INDEXING_SLICING,
- expr.span,
- "slicing may panic.",
- help_msg,
- );
- } else {
- utils::span_help_and_lint(
- cx,
- INDEXING_SLICING,
- expr.span,
- "indexing may panic.",
- "Consider using `.get(n)` or `.get_mut(n)` instead",
- );
+ return;
}
}
- ExprLit(..) => {
- // [n]
- if let ty::TyArray(_, s) = ty.sty {
- let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
- // Index is a constant uint.
- if let Some((Constant::Int(const_index), _)) =
- constant(cx, cx.tables, index)
- {
- if size <= const_index {
- utils::span_lint(
- cx,
- OUT_OF_BOUNDS_INDEXING,
- expr.span,
- "const index is out of bounds",
- );
- }
- // Else index is in bounds, ok.
+
+ let help_msg = match (range.start, range.end) {
+ (None, Some(_)) => "Consider using `.get(..n)`or `.get_mut(..n)` instead",
+ (Some(_), None) => "Consider using `.get(n..)` or .get_mut(n..)` instead",
+ (Some(_), Some(_)) => "Consider using `.get(n..m)` or `.get_mut(n..m)` instead",
+ (None, None) => return, // [..] is ok.
+ };
+
+ utils::span_help_and_lint(
+ cx,
+ INDEXING_SLICING,
+ expr.span,
+ "slicing may panic.",
+ help_msg,
+ );
+ } else {
+ // Catchall non-range index, i.e. [n] or [n << m]
+ if let ty::TyArray(_, s) = ty.sty {
+ let size: u128 = s.assert_usize(cx.tcx).unwrap().into();
+ // Index is a constant uint.
+ if let Some((Constant::Int(const_index), _)) = constant(cx, cx.tables, index) {
+ if size <= const_index {
+ utils::span_lint(
+ cx,
+ OUT_OF_BOUNDS_INDEXING,
+ expr.span,
+ "const index is out of bounds",
+ );
}
- } else {
- utils::span_help_and_lint(
- cx,
- INDEXING_SLICING,
- expr.span,
- "indexing may panic.",
- "Consider using `.get(n)` or `.get_mut(n)` instead",
- );
+ // Else index is in bounds, ok.
+
+ return;
}
}
- _ => (),
+
+ utils::span_help_and_lint(
+ cx,
+ INDEXING_SLICING,
+ expr.span,
+ "indexing may panic.",
+ "Consider using `.get(n)` or `.get_mut(n)` instead",
+ );
}
}
}
diff --git a/tests/ui/indexing_slicing.rs b/tests/ui/indexing_slicing.rs
index a22c9034346..16174afb106 100644
--- a/tests/ui/indexing_slicing.rs
+++ b/tests/ui/indexing_slicing.rs
@@ -9,55 +9,63 @@ fn main() {
let index_from: usize = 2;
let index_to: usize = 3;
x[index];
- &x[index_from..index_to];
- &x[index_from..][..index_to];
&x[index..];
&x[..index];
- x[0];
- x[3];
+ &x[index_from..index_to];
+ &x[index_from..][..index_to]; // Two lint reports, one for [index_from..] and another for [..index_to].
x[4];
x[1 << 3];
- &x[1..5];
- &x[1..][..5];
- &x[0..3];
- &x[0..][..3];
- &x[0..].get(..3); // Ok
- &x[0..=4];
&x[..=4];
- &x[..];
- &x[1..];
- &x[4..];
+ &x[1..5];
+ &x[5..][..10]; // Two lint reports, one for [5..] and another for [..10].
&x[5..];
- &x[..4];
&x[..5];
&x[5..].iter().map(|x| 2 * x).collect::<Vec<i32>>();
- &x[2..].iter().map(|x| 2 * x).collect::<Vec<i32>>(); // Ok
+ &x[0..=4];
+ &x[0..][..3];
+ &x[1..][..5];
+
+ &x[4..]; // Ok, should not produce stderr.
+ &x[..4]; // Ok, should not produce stderr.
+ &x[..]; // Ok, should not produce stderr.
+ &x[1..]; // Ok, should not produce stderr.
+ &x[2..].iter().map(|x| 2 * x).collect::<Vec<i32>>(); // Ok, should not produce stderr.
+ &x[0..].get(..3); // Ok, should not produce stderr.
+ x[0]; // Ok, should not produce stderr.
+ x[3]; // Ok, should not produce stderr.
+ &x[0..3]; // Ok, should not produce stderr.
let y = &x;
y[0];
&y[1..2];
- &y[..];
&y[0..=4];
&y[..=4];
+ &y[..]; // Ok, should not produce stderr.
+
let empty: [i8; 0] = [];
empty[0];
&empty[1..5];
&empty[0..=4];
&empty[..=4];
- &empty[..];
- &empty[0..];
- &empty[0..0];
- &empty[0..=0];
- &empty[..=0];
- &empty[..0];
&empty[1..];
&empty[..4];
+ &empty[0..=0];
+ &empty[..=0];
+
+ &empty[0..]; // Ok, should not produce stderr.
+ &empty[0..0]; // Ok, should not produce stderr.
+ &empty[..0]; // Ok, should not produce stderr.
+ &empty[..]; // Ok, should not produce stderr.
let v = vec![0; 5];
v[0];
v[10];
+ v[1 << 3];
&v[10..100];
+ &x[10..][..100]; // Two lint reports, one for [10..] and another for [..100].
&v[10..];
&v[..100];
+
+ &v[..]; // Ok, should not produce stderr.
}
diff --git a/tests/ui/indexing_slicing.stderr b/tests/ui/indexing_slicing.stderr
index 605a96e8b8c..c9aefe0349a 100644
--- a/tests/ui/indexing_slicing.stderr
+++ b/tests/ui/indexing_slicing.stderr
@@ -10,109 +10,135 @@ error: indexing may panic.
error: slicing may panic.
--> $DIR/indexing_slicing.rs:12:6
|
-12 | &x[index_from..index_to];
+12 | &x[index..];
+ | ^^^^^^^^^^
+ |
+ = help: Consider using `.get(n..)` or .get_mut(n..)` instead
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:13:6
+ |
+13 | &x[..index];
+ | ^^^^^^^^^^
+ |
+ = help: Consider using `.get(..n)`or `.get_mut(..n)` instead
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:14:6
+ |
+14 | &x[index_from..index_to];
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: Consider using `.get(n..m)` or `.get_mut(n..m)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:13:6
+ --> $DIR/indexing_slicing.rs:15:6
|
-13 | &x[index_from..][..index_to];
+15 | &x[index_from..][..index_to]; // Two lint reports, one for [index_from..] and another for [..index_to].
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:13:6
+ --> $DIR/indexing_slicing.rs:15:6
|
-13 | &x[index_from..][..index_to];
+15 | &x[index_from..][..index_to]; // Two lint reports, one for [index_from..] and another for [..index_to].
| ^^^^^^^^^^^^^^^
|
= help: Consider using `.get(n..)` or .get_mut(n..)` instead
-error: slicing may panic.
- --> $DIR/indexing_slicing.rs:14:6
- |
-14 | &x[index..];
- | ^^^^^^^^^^
- |
- = help: Consider using `.get(n..)` or .get_mut(n..)` instead
-
-error: slicing may panic.
- --> $DIR/indexing_slicing.rs:15:6
- |
-15 | &x[..index];
- | ^^^^^^^^^^
- |
- = help: Consider using `.get(..n)`or `.get_mut(..n)` instead
-
error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:18:5
+ --> $DIR/indexing_slicing.rs:16:5
|
-18 | x[4];
+16 | x[4];
| ^^^^
|
= note: `-D out-of-bounds-indexing` implied by `-D warnings`
+error: const index is out of bounds
+ --> $DIR/indexing_slicing.rs:17:5
+ |
+17 | x[1 << 3];
+ | ^^^^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:18:6
+ |
+18 | &x[..=4];
+ | ^^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:19:6
+ |
+19 | &x[1..5];
+ | ^^^^^^^
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:20:6
+ |
+20 | &x[5..][..10]; // Two lint reports, one for [5..] and another for [..10].
+ | ^^^^^^^^^^^^
+ |
+ = help: Consider using `.get(..n)`or `.get_mut(..n)` instead
+
error: range is out of bounds
--> $DIR/indexing_slicing.rs:20:6
|
-20 | &x[1..5];
- | ^^^^^^^
+20 | &x[5..][..10]; // Two lint reports, one for [5..] and another for [..10].
+ | ^^^^^^
-error: slicing may panic.
+error: range is out of bounds
--> $DIR/indexing_slicing.rs:21:6
|
-21 | &x[1..][..5];
+21 | &x[5..];
+ | ^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:22:6
+ |
+22 | &x[..5];
+ | ^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:23:6
+ |
+23 | &x[5..].iter().map(|x| 2 * x).collect::<Vec<i32>>();
+ | ^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:24:6
+ |
+24 | &x[0..=4];
+ | ^^^^^^^^
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:25:6
+ |
+25 | &x[0..][..3];
| ^^^^^^^^^^^
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:23:6
+ --> $DIR/indexing_slicing.rs:26:6
|
-23 | &x[0..][..3];
+26 | &x[1..][..5];
| ^^^^^^^^^^^
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
-error: range is out of bounds
- --> $DIR/indexing_slicing.rs:26:6
- |
-26 | &x[..=4];
- | ^^^^^^^
-
-error: range is out of bounds
- --> $DIR/indexing_slicing.rs:30:6
- |
-30 | &x[5..];
- | ^^^^^^
-
-error: range is out of bounds
- --> $DIR/indexing_slicing.rs:32:6
- |
-32 | &x[..5];
- | ^^^^^^
-
-error: range is out of bounds
- --> $DIR/indexing_slicing.rs:33:6
- |
-33 | &x[5..].iter().map(|x| 2 * x).collect::<Vec<i32>>();
- | ^^^^^^
-
error: indexing may panic.
- --> $DIR/indexing_slicing.rs:37:5
+ --> $DIR/indexing_slicing.rs:39:5
|
-37 | y[0];
+39 | y[0];
| ^^^^
|
= help: Consider using `.get(n)` or `.get_mut(n)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:38:6
+ --> $DIR/indexing_slicing.rs:40:6
|
-38 | &y[1..2];
+40 | &y[1..2];
| ^^^^^^^
|
= help: Consider using `.get(n..m)` or `.get_mut(n..m)` instead
@@ -120,86 +146,128 @@ error: slicing may panic.
error: slicing may panic.
--> $DIR/indexing_slicing.rs:41:6
|
-41 | &y[..=4];
+41 | &y[0..=4];
+ | ^^^^^^^^
+ |
+ = help: Consider using `.get(n..m)` or `.get_mut(n..m)` instead
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:42:6
+ |
+42 | &y[..=4];
| ^^^^^^^
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
error: const index is out of bounds
- --> $DIR/indexing_slicing.rs:44:5
+ --> $DIR/indexing_slicing.rs:47:5
|
-44 | empty[0];
+47 | empty[0];
| ^^^^^^^^
error: range is out of bounds
- --> $DIR/indexing_slicing.rs:45:6
+ --> $DIR/indexing_slicing.rs:48:6
|
-45 | &empty[1..5];
+48 | &empty[1..5];
| ^^^^^^^^^^^
error: range is out of bounds
- --> $DIR/indexing_slicing.rs:47:6
+ --> $DIR/indexing_slicing.rs:49:6
|
-47 | &empty[..=4];
+49 | &empty[0..=4];
+ | ^^^^^^^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:50:6
+ |
+50 | &empty[..=4];
| ^^^^^^^^^^^
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:51:6
+ |
+51 | &empty[1..];
+ | ^^^^^^^^^^
+
error: range is out of bounds
--> $DIR/indexing_slicing.rs:52:6
|
-52 | &empty[..=0];
- | ^^^^^^^^^^^
+52 | &empty[..4];
+ | ^^^^^^^^^^
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:53:6
+ |
+53 | &empty[0..=0];
+ | ^^^^^^^^^^^^
error: range is out of bounds
--> $DIR/indexing_slicing.rs:54:6
|
-54 | &empty[1..];
- | ^^^^^^^^^^
-
-error: range is out of bounds
- --> $DIR/indexing_slicing.rs:55:6
- |
-55 | &empty[..4];
- | ^^^^^^^^^^
+54 | &empty[..=0];
+ | ^^^^^^^^^^^
error: indexing may panic.
- --> $DIR/indexing_slicing.rs:58:5
+ --> $DIR/indexing_slicing.rs:62:5
|
-58 | v[0];
+62 | v[0];
| ^^^^
|
= help: Consider using `.get(n)` or `.get_mut(n)` instead
error: indexing may panic.
- --> $DIR/indexing_slicing.rs:59:5
+ --> $DIR/indexing_slicing.rs:63:5
|
-59 | v[10];
+63 | v[10];
| ^^^^^
|
= help: Consider using `.get(n)` or `.get_mut(n)` instead
-error: slicing may panic.
- --> $DIR/indexing_slicing.rs:60:6
+error: indexing may panic.
+ --> $DIR/indexing_slicing.rs:64:5
|
-60 | &v[10..100];
+64 | v[1 << 3];
+ | ^^^^^^^^^
+ |
+ = help: Consider using `.get(n)` or `.get_mut(n)` instead
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:65:6
+ |
+65 | &v[10..100];
| ^^^^^^^^^^
|
= help: Consider using `.get(n..m)` or `.get_mut(n..m)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:61:6
+ --> $DIR/indexing_slicing.rs:66:6
|
-61 | &v[10..];
+66 | &x[10..][..100]; // Two lint reports, one for [10..] and another for [..100].
+ | ^^^^^^^^^^^^^^
+ |
+ = help: Consider using `.get(..n)`or `.get_mut(..n)` instead
+
+error: range is out of bounds
+ --> $DIR/indexing_slicing.rs:66:6
+ |
+66 | &x[10..][..100]; // Two lint reports, one for [10..] and another for [..100].
+ | ^^^^^^^
+
+error: slicing may panic.
+ --> $DIR/indexing_slicing.rs:67:6
+ |
+67 | &v[10..];
| ^^^^^^^
|
= help: Consider using `.get(n..)` or .get_mut(n..)` instead
error: slicing may panic.
- --> $DIR/indexing_slicing.rs:62:6
+ --> $DIR/indexing_slicing.rs:68:6
|
-62 | &v[..100];
+68 | &v[..100];
| ^^^^^^^^
|
= help: Consider using `.get(..n)`or `.get_mut(..n)` instead
-error: aborting due to 28 previous errors
+error: aborting due to 38 previous errors