From 21eae8ceb6ff58b592b00cab58cda62a96aad51a Mon Sep 17 00:00:00 2001 From: Peter Jaszkowiak Date: Fri, 25 Mar 2022 23:05:38 -0600 Subject: [PATCH] fix `indexing_slicing` with const - should not fire if indexing with a constant block - should not fire if indexing within a constant context (const statement or const block) --- clippy_lints/src/indexing_slicing.rs | 8 ++++++++ tests/ui/indexing_slicing_index.rs | 24 +++++++++++++++++++---- tests/ui/indexing_slicing_index.stderr | 27 +++++++++++++++++++------- 3 files changed, 48 insertions(+), 11 deletions(-) diff --git a/clippy_lints/src/indexing_slicing.rs b/clippy_lints/src/indexing_slicing.rs index 9ead4bb27a5..4ba7477add8 100644 --- a/clippy_lints/src/indexing_slicing.rs +++ b/clippy_lints/src/indexing_slicing.rs @@ -96,6 +96,10 @@ declare_lint_pass!(IndexingSlicing => [INDEXING_SLICING, OUT_OF_BOUNDS_INDEXING] impl<'tcx> LateLintPass<'tcx> for IndexingSlicing { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { + if cx.tcx.hir().is_inside_const_context(expr.hir_id) { + return; + } + if let ExprKind::Index(array, index) = &expr.kind { let ty = cx.typeck_results().expr_ty(array).peel_refs(); if let Some(range) = higher::Range::hir(index) { @@ -151,6 +155,10 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing { } else { // Catchall non-range index, i.e., [n] or [n << m] if let ty::Array(..) = ty.kind() { + // Index is a const block. + if let ExprKind::ConstBlock(..) = index.kind { + return; + } // Index is a constant uint. if let Some(..) = constant(cx, cx.typeck_results(), index) { // Let rustc's `const_err` lint handle constant `usize` indexing on arrays. diff --git a/tests/ui/indexing_slicing_index.rs b/tests/ui/indexing_slicing_index.rs index ca8ca53c80c..45a430edcb5 100644 --- a/tests/ui/indexing_slicing_index.rs +++ b/tests/ui/indexing_slicing_index.rs @@ -1,18 +1,34 @@ +#![feature(inline_const)] #![warn(clippy::indexing_slicing)] // We also check the out_of_bounds_indexing lint here, because it lints similar things and // we want to avoid false positives. #![warn(clippy::out_of_bounds_indexing)] -#![allow(clippy::no_effect, clippy::unnecessary_operation)] +#![allow(const_err, clippy::no_effect, clippy::unnecessary_operation)] + +const ARR: [i32; 2] = [1, 2]; +const REF: &i32 = &ARR[idx()]; // Ok, should not produce stderr. +const REF_ERR: &i32 = &ARR[idx4()]; // Ok, let rustc handle const contexts. + +const fn idx() -> usize { + 1 +} +const fn idx4() -> usize { + 4 +} fn main() { let x = [1, 2, 3, 4]; let index: usize = 1; x[index]; - x[4]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays. - x[1 << 3]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays. + x[4]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays. + x[1 << 3]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays. x[0]; // Ok, should not produce stderr. x[3]; // Ok, should not produce stderr. + x[const { idx() }]; // Ok, should not produce stderr. + x[const { idx4() }]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays. + const { &ARR[idx()] }; // Ok, should not produce stderr. + const { &ARR[idx4()] }; // Ok, let rustc handle const contexts. let y = &x; y[0]; // Ok, referencing shouldn't affect this lint. See the issue 6021 @@ -25,7 +41,7 @@ fn main() { const N: usize = 15; // Out of bounds const M: usize = 3; // In bounds - x[N]; // Ok, let rustc's `const_err` lint handle `usize` indexing on arrays. + x[N]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays. x[M]; // Ok, should not produce stderr. v[N]; v[M]; diff --git a/tests/ui/indexing_slicing_index.stderr b/tests/ui/indexing_slicing_index.stderr index 76ecec33484..83a36f407d5 100644 --- a/tests/ui/indexing_slicing_index.stderr +++ b/tests/ui/indexing_slicing_index.stderr @@ -1,5 +1,17 @@ +error[E0080]: evaluation of `main::{constant#3}::<&i32>` failed + --> $DIR/indexing_slicing_index.rs:31:14 + | +LL | const { &ARR[idx4()] }; // Ok, let rustc handle const contexts. + | ^^^^^^^^^^^ index out of bounds: the length is 2 but the index is 4 + +error[E0080]: erroneous constant used + --> $DIR/indexing_slicing_index.rs:31:5 + | +LL | const { &ARR[idx4()] }; // Ok, let rustc handle const contexts. + | ^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors + error: indexing may panic - --> $DIR/indexing_slicing_index.rs:10:5 + --> $DIR/indexing_slicing_index.rs:22:5 | LL | x[index]; | ^^^^^^^^ @@ -8,7 +20,7 @@ LL | x[index]; = help: consider using `.get(n)` or `.get_mut(n)` instead error: indexing may panic - --> $DIR/indexing_slicing_index.rs:22:5 + --> $DIR/indexing_slicing_index.rs:38:5 | LL | v[0]; | ^^^^ @@ -16,7 +28,7 @@ LL | v[0]; = help: consider using `.get(n)` or `.get_mut(n)` instead error: indexing may panic - --> $DIR/indexing_slicing_index.rs:23:5 + --> $DIR/indexing_slicing_index.rs:39:5 | LL | v[10]; | ^^^^^ @@ -24,7 +36,7 @@ LL | v[10]; = help: consider using `.get(n)` or `.get_mut(n)` instead error: indexing may panic - --> $DIR/indexing_slicing_index.rs:24:5 + --> $DIR/indexing_slicing_index.rs:40:5 | LL | v[1 << 3]; | ^^^^^^^^^ @@ -32,7 +44,7 @@ LL | v[1 << 3]; = help: consider using `.get(n)` or `.get_mut(n)` instead error: indexing may panic - --> $DIR/indexing_slicing_index.rs:30:5 + --> $DIR/indexing_slicing_index.rs:46:5 | LL | v[N]; | ^^^^ @@ -40,12 +52,13 @@ LL | v[N]; = help: consider using `.get(n)` or `.get_mut(n)` instead error: indexing may panic - --> $DIR/indexing_slicing_index.rs:31:5 + --> $DIR/indexing_slicing_index.rs:47:5 | LL | v[M]; | ^^^^ | = help: consider using `.get(n)` or `.get_mut(n)` instead -error: aborting due to 6 previous errors +error: aborting due to 8 previous errors +For more information about this error, try `rustc --explain E0080`.