From 7a80f7b790333aed3b456db01d6c3dd26c69d487 Mon Sep 17 00:00:00 2001 From: Lukas Lueg Date: Sun, 15 Sep 2024 18:53:10 +0200 Subject: [PATCH] Initial impl `repr_packed_without_abi` Fixes #13375 --- CHANGELOG.md | 1 + clippy_lints/src/attrs/mod.rs | 41 +++++++++++++++++++ clippy_lints/src/attrs/repr_attributes.rs | 43 ++++++++++++++++++++ clippy_lints/src/declared_lints.rs | 1 + clippy_utils/src/msrvs.rs | 1 + tests/ui/default_union_representation.rs | 1 + tests/ui/default_union_representation.stderr | 8 ++-- tests/ui/derive.rs | 1 + tests/ui/derive.stderr | 20 ++++----- tests/ui/repr_packed_without_abi.rs | 37 +++++++++++++++++ tests/ui/repr_packed_without_abi.stderr | 35 ++++++++++++++++ tests/ui/trailing_empty_array.rs | 1 + tests/ui/trailing_empty_array.stderr | 22 +++++----- 13 files changed, 187 insertions(+), 25 deletions(-) create mode 100644 clippy_lints/src/attrs/repr_attributes.rs create mode 100644 tests/ui/repr_packed_without_abi.rs create mode 100644 tests/ui/repr_packed_without_abi.stderr diff --git a/CHANGELOG.md b/CHANGELOG.md index cc966972939a..529ab6c20d62 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -5969,6 +5969,7 @@ Released 2018-09-13 [`repeat_once`]: https://rust-lang.github.io/rust-clippy/master/index.html#repeat_once [`repeat_vec_with_capacity`]: https://rust-lang.github.io/rust-clippy/master/index.html#repeat_vec_with_capacity [`replace_consts`]: https://rust-lang.github.io/rust-clippy/master/index.html#replace_consts +[`repr_packed_without_abi`]: https://rust-lang.github.io/rust-clippy/master/index.html#repr_packed_without_abi [`reserve_after_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#reserve_after_initialization [`rest_pat_in_fully_bound_structs`]: https://rust-lang.github.io/rust-clippy/master/index.html#rest_pat_in_fully_bound_structs [`result_expect_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_expect_used diff --git a/clippy_lints/src/attrs/mod.rs b/clippy_lints/src/attrs/mod.rs index a9766597d50d..92efd1a4ddcd 100644 --- a/clippy_lints/src/attrs/mod.rs +++ b/clippy_lints/src/attrs/mod.rs @@ -7,6 +7,7 @@ mod duplicated_attributes; mod inline_always; mod mixed_attributes_style; mod non_minimal_cfg; +mod repr_attributes; mod should_panic_without_expect; mod unnecessary_clippy_cfg; mod useless_attribute; @@ -272,6 +273,44 @@ declare_clippy_lint! { "ensures that all `should_panic` attributes specify its expected panic message" } +declare_clippy_lint! { + /// ### What it does + /// Checks for items with `#[repr(packed)]`-attribute without ABI qualification + /// + /// ### Why is this bad? + /// Without qualification, `repr(packed)` implies `repr(Rust)`. The Rust-ABI is inherently unstable. + /// While this is fine as long as the type is accessed correctly within Rust-code, most uses + /// of `#[repr(packed)]` involve FFI and/or data structures specified by network-protocols or + /// other external specifications. In such situations, the unstable Rust-ABI implied in + /// `#[repr(packed)]` may lead to future bugs should the Rust-ABI change. + /// + /// In case you are relying on a well defined and stable memory layout, qualify the type's + /// representation using the `C`-ABI. Otherwise, if the type in question is only ever + /// accessed from Rust-code according to Rust's rules, use the `Rust`-ABI explicitly. + /// + /// ### Example + /// ```no_run + /// #[repr(packed)] + /// struct NetworkPacketHeader { + /// header_length: u8, + /// header_version: u16 + /// } + /// ``` + /// + /// Use instead: + /// ```no_run + /// #[repr(C, packed)] + /// struct NetworkPacketHeader { + /// header_length: u8, + /// header_version: u16 + /// } + /// ``` + #[clippy::version = "1.84.0"] + pub REPR_PACKED_WITHOUT_ABI, + suspicious, + "ensures that `repr(packed)` always comes with a qualified ABI" +} + declare_clippy_lint! { /// ### What it does /// Checks for `any` and `all` combinators in `cfg` with only one condition. @@ -415,6 +454,7 @@ pub struct Attributes { impl_lint_pass!(Attributes => [ INLINE_ALWAYS, + REPR_PACKED_WITHOUT_ABI, ]); impl Attributes { @@ -431,6 +471,7 @@ impl<'tcx> LateLintPass<'tcx> for Attributes { if is_relevant_item(cx, item) { inline_always::check(cx, item.span, item.ident.name, attrs); } + repr_attributes::check(cx, item.span, attrs, &self.msrv); } fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) { diff --git a/clippy_lints/src/attrs/repr_attributes.rs b/clippy_lints/src/attrs/repr_attributes.rs new file mode 100644 index 000000000000..e55a85b62671 --- /dev/null +++ b/clippy_lints/src/attrs/repr_attributes.rs @@ -0,0 +1,43 @@ +use rustc_ast::Attribute; +use rustc_lint::LateContext; +use rustc_span::{Span, sym}; + +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::msrvs; + +use super::REPR_PACKED_WITHOUT_ABI; + +pub(super) fn check(cx: &LateContext<'_>, item_span: Span, attrs: &[Attribute], msrv: &msrvs::Msrv) { + if msrv.meets(msrvs::REPR_RUST) { + check_packed(cx, item_span, attrs); + } +} + +fn check_packed(cx: &LateContext<'_>, item_span: Span, attrs: &[Attribute]) { + if let Some(items) = attrs.iter().find_map(|attr| { + if attr.ident().is_some_and(|ident| matches!(ident.name, sym::repr)) { + attr.meta_item_list() + } else { + None + } + }) && let Some(packed) = items + .iter() + .find(|item| item.ident().is_some_and(|ident| matches!(ident.name, sym::packed))) + && !items.iter().any(|item| { + item.ident() + .is_some_and(|ident| matches!(ident.name, sym::C | sym::Rust)) + }) + { + span_lint_and_then( + cx, + REPR_PACKED_WITHOUT_ABI, + item_span, + "item uses `packed` representation without ABI-qualification", + |diag| { + diag.warn("unqualified `#[repr(packed)]` defaults to `#[repr(Rust, packed)]`, which has no stable ABI") + .help("qualify the desired ABI explicity via `#[repr(C, packed)]` or `#[repr(Rust, packed)]`") + .span_label(packed.span(), "`packed` representation set here"); + }, + ); + } +} diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index 304622afe530..d2a8f23b60fb 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -55,6 +55,7 @@ pub static LINTS: &[&crate::LintInfo] = &[ crate::attrs::INLINE_ALWAYS_INFO, crate::attrs::MIXED_ATTRIBUTES_STYLE_INFO, crate::attrs::NON_MINIMAL_CFG_INFO, + crate::attrs::REPR_PACKED_WITHOUT_ABI_INFO, crate::attrs::SHOULD_PANIC_WITHOUT_EXPECT_INFO, crate::attrs::UNNECESSARY_CLIPPY_CFG_INFO, crate::attrs::USELESS_ATTRIBUTE_INFO, diff --git a/clippy_utils/src/msrvs.rs b/clippy_utils/src/msrvs.rs index f03817607095..35f552c15a3d 100644 --- a/clippy_utils/src/msrvs.rs +++ b/clippy_utils/src/msrvs.rs @@ -24,6 +24,7 @@ msrv_aliases! { 1,80,0 { BOX_INTO_ITER } 1,77,0 { C_STR_LITERALS } 1,76,0 { PTR_FROM_REF, OPTION_RESULT_INSPECT } + 1,74,0 { REPR_RUST } 1,73,0 { MANUAL_DIV_CEIL } 1,71,0 { TUPLE_ARRAY_CONVERSIONS, BUILD_HASHER_HASH_ONE } 1,70,0 { OPTION_RESULT_IS_VARIANT_AND, BINARY_HEAP_RETAIN } diff --git a/tests/ui/default_union_representation.rs b/tests/ui/default_union_representation.rs index 41308b077bac..ba63cde2fa9d 100644 --- a/tests/ui/default_union_representation.rs +++ b/tests/ui/default_union_representation.rs @@ -1,5 +1,6 @@ #![feature(transparent_unions)] #![warn(clippy::default_union_representation)] +#![allow(clippy::repr_packed_without_abi)] union NoAttribute { //~^ ERROR: this union has the default representation diff --git a/tests/ui/default_union_representation.stderr b/tests/ui/default_union_representation.stderr index c7ef70a0b8e7..d558a3e8de1b 100644 --- a/tests/ui/default_union_representation.stderr +++ b/tests/ui/default_union_representation.stderr @@ -1,5 +1,5 @@ error: this union has the default representation - --> tests/ui/default_union_representation.rs:4:1 + --> tests/ui/default_union_representation.rs:5:1 | LL | / union NoAttribute { LL | | @@ -13,7 +13,7 @@ LL | | } = help: to override `-D warnings` add `#[allow(clippy::default_union_representation)]` error: this union has the default representation - --> tests/ui/default_union_representation.rs:17:1 + --> tests/ui/default_union_representation.rs:18:1 | LL | / union ReprPacked { LL | | @@ -25,7 +25,7 @@ LL | | } = help: consider annotating `ReprPacked` with `#[repr(C)]` to explicitly specify memory layout error: this union has the default representation - --> tests/ui/default_union_representation.rs:36:1 + --> tests/ui/default_union_representation.rs:37:1 | LL | / union ReprAlign { LL | | @@ -37,7 +37,7 @@ LL | | } = help: consider annotating `ReprAlign` with `#[repr(C)]` to explicitly specify memory layout error: this union has the default representation - --> tests/ui/default_union_representation.rs:57:1 + --> tests/ui/default_union_representation.rs:58:1 | LL | / union ZSTAndTwoFields { LL | | diff --git a/tests/ui/derive.rs b/tests/ui/derive.rs index 3647b2425058..dabc06bd7d16 100644 --- a/tests/ui/derive.rs +++ b/tests/ui/derive.rs @@ -2,6 +2,7 @@ clippy::non_canonical_clone_impl, clippy::non_canonical_partial_ord_impl, clippy::needless_lifetimes, + clippy::repr_packed_without_abi, dead_code )] #![warn(clippy::expl_impl_clone_on_copy)] diff --git a/tests/ui/derive.stderr b/tests/ui/derive.stderr index c072a9a6277b..0eb4b3c1adaa 100644 --- a/tests/ui/derive.stderr +++ b/tests/ui/derive.stderr @@ -1,5 +1,5 @@ error: you are implementing `Clone` explicitly on a `Copy` type - --> tests/ui/derive.rs:12:1 + --> tests/ui/derive.rs:13:1 | LL | / impl Clone for Qux { LL | | @@ -10,7 +10,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> tests/ui/derive.rs:12:1 + --> tests/ui/derive.rs:13:1 | LL | / impl Clone for Qux { LL | | @@ -23,7 +23,7 @@ LL | | } = help: to override `-D warnings` add `#[allow(clippy::expl_impl_clone_on_copy)]` error: you are implementing `Clone` explicitly on a `Copy` type - --> tests/ui/derive.rs:37:1 + --> tests/ui/derive.rs:38:1 | LL | / impl<'a> Clone for Lt<'a> { LL | | @@ -34,7 +34,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> tests/ui/derive.rs:37:1 + --> tests/ui/derive.rs:38:1 | LL | / impl<'a> Clone for Lt<'a> { LL | | @@ -45,7 +45,7 @@ LL | | } | |_^ error: you are implementing `Clone` explicitly on a `Copy` type - --> tests/ui/derive.rs:49:1 + --> tests/ui/derive.rs:50:1 | LL | / impl Clone for BigArray { LL | | @@ -56,7 +56,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> tests/ui/derive.rs:49:1 + --> tests/ui/derive.rs:50:1 | LL | / impl Clone for BigArray { LL | | @@ -67,7 +67,7 @@ LL | | } | |_^ error: you are implementing `Clone` explicitly on a `Copy` type - --> tests/ui/derive.rs:61:1 + --> tests/ui/derive.rs:62:1 | LL | / impl Clone for FnPtr { LL | | @@ -78,7 +78,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> tests/ui/derive.rs:61:1 + --> tests/ui/derive.rs:62:1 | LL | / impl Clone for FnPtr { LL | | @@ -89,7 +89,7 @@ LL | | } | |_^ error: you are implementing `Clone` explicitly on a `Copy` type - --> tests/ui/derive.rs:82:1 + --> tests/ui/derive.rs:83:1 | LL | / impl Clone for Generic2 { LL | | @@ -100,7 +100,7 @@ LL | | } | |_^ | note: consider deriving `Clone` or removing `Copy` - --> tests/ui/derive.rs:82:1 + --> tests/ui/derive.rs:83:1 | LL | / impl Clone for Generic2 { LL | | diff --git a/tests/ui/repr_packed_without_abi.rs b/tests/ui/repr_packed_without_abi.rs new file mode 100644 index 000000000000..16b5ededee99 --- /dev/null +++ b/tests/ui/repr_packed_without_abi.rs @@ -0,0 +1,37 @@ +#![deny(clippy::repr_packed_without_abi)] + +#[repr(packed)] +struct NetworkPacketHeader { + header_length: u8, + header_version: u16, +} + +#[repr(packed)] +union Foo { + a: u8, + b: u16, +} + +#[repr(C, packed)] +struct NoLintCNetworkPacketHeader { + header_length: u8, + header_version: u16, +} + +#[repr(Rust, packed)] +struct NoLintRustNetworkPacketHeader { + header_length: u8, + header_version: u16, +} + +#[repr(packed, C)] +union NotLintCFoo { + a: u8, + b: u16, +} + +#[repr(packed, Rust)] +union NotLintRustFoo { + a: u8, + b: u16, +} diff --git a/tests/ui/repr_packed_without_abi.stderr b/tests/ui/repr_packed_without_abi.stderr new file mode 100644 index 000000000000..4f7acd00db3d --- /dev/null +++ b/tests/ui/repr_packed_without_abi.stderr @@ -0,0 +1,35 @@ +error: item uses `packed` representation without ABI-qualification + --> tests/ui/repr_packed_without_abi.rs:4:1 + | +LL | #[repr(packed)] + | ------ `packed` representation set here +LL | / struct NetworkPacketHeader { +LL | | header_length: u8, +LL | | header_version: u16, +LL | | } + | |_^ + | + = warning: unqualified `#[repr(packed)]` defaults to `#[repr(Rust, packed)]`, which has no stable ABI + = help: qualify the desired ABI explicity via `#[repr(C, packed)]` or `#[repr(Rust, packed)]` +note: the lint level is defined here + --> tests/ui/repr_packed_without_abi.rs:1:9 + | +LL | #![deny(clippy::repr_packed_without_abi)] + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: item uses `packed` representation without ABI-qualification + --> tests/ui/repr_packed_without_abi.rs:10:1 + | +LL | #[repr(packed)] + | ------ `packed` representation set here +LL | / union Foo { +LL | | a: u8, +LL | | b: u16, +LL | | } + | |_^ + | + = warning: unqualified `#[repr(packed)]` defaults to `#[repr(Rust, packed)]`, which has no stable ABI + = help: qualify the desired ABI explicity via `#[repr(C, packed)]` or `#[repr(Rust, packed)]` + +error: aborting due to 2 previous errors + diff --git a/tests/ui/trailing_empty_array.rs b/tests/ui/trailing_empty_array.rs index 3d06c2621681..309a5920dfde 100644 --- a/tests/ui/trailing_empty_array.rs +++ b/tests/ui/trailing_empty_array.rs @@ -1,4 +1,5 @@ #![warn(clippy::trailing_empty_array)] +#![allow(clippy::repr_packed_without_abi)] // Do lint: diff --git a/tests/ui/trailing_empty_array.stderr b/tests/ui/trailing_empty_array.stderr index 756381478f2b..7ebff372cf75 100644 --- a/tests/ui/trailing_empty_array.stderr +++ b/tests/ui/trailing_empty_array.stderr @@ -1,5 +1,5 @@ error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:5:1 + --> tests/ui/trailing_empty_array.rs:6:1 | LL | / struct RarelyUseful { LL | | @@ -13,7 +13,7 @@ LL | | } = help: to override `-D warnings` add `#[allow(clippy::trailing_empty_array)]` error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:11:1 + --> tests/ui/trailing_empty_array.rs:12:1 | LL | / struct OnlyField { LL | | @@ -24,7 +24,7 @@ LL | | } = help: consider annotating `OnlyField` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:16:1 + --> tests/ui/trailing_empty_array.rs:17:1 | LL | / struct GenericArrayType { LL | | @@ -36,7 +36,7 @@ LL | | } = help: consider annotating `GenericArrayType` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:23:1 + --> tests/ui/trailing_empty_array.rs:24:1 | LL | / struct OnlyAnotherAttribute { LL | | @@ -48,7 +48,7 @@ LL | | } = help: consider annotating `OnlyAnotherAttribute` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:30:1 + --> tests/ui/trailing_empty_array.rs:31:1 | LL | / struct OnlyADeriveAttribute { LL | | @@ -60,7 +60,7 @@ LL | | } = help: consider annotating `OnlyADeriveAttribute` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:37:1 + --> tests/ui/trailing_empty_array.rs:38:1 | LL | / struct ZeroSizedWithConst { LL | | @@ -72,7 +72,7 @@ LL | | } = help: consider annotating `ZeroSizedWithConst` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:47:1 + --> tests/ui/trailing_empty_array.rs:48:1 | LL | / struct ZeroSizedWithConstFunction { LL | | @@ -84,7 +84,7 @@ LL | | } = help: consider annotating `ZeroSizedWithConstFunction` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:56:1 + --> tests/ui/trailing_empty_array.rs:57:1 | LL | / struct ZeroSizedWithConstFunction2 { LL | | @@ -96,7 +96,7 @@ LL | | } = help: consider annotating `ZeroSizedWithConstFunction2` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:62:1 + --> tests/ui/trailing_empty_array.rs:63:1 | LL | struct ZeroSizedArrayWrapper([usize; 0]); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -104,7 +104,7 @@ LL | struct ZeroSizedArrayWrapper([usize; 0]); = help: consider annotating `ZeroSizedArrayWrapper` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:65:1 + --> tests/ui/trailing_empty_array.rs:66:1 | LL | struct TupleStruct(i32, [usize; 0]); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -112,7 +112,7 @@ LL | struct TupleStruct(i32, [usize; 0]); = help: consider annotating `TupleStruct` with `#[repr(C)]` or another `repr` attribute error: trailing zero-sized array in a struct which is not marked with a `repr` attribute - --> tests/ui/trailing_empty_array.rs:68:1 + --> tests/ui/trailing_empty_array.rs:69:1 | LL | / struct LotsOfFields { LL | |