diff --git a/CHANGELOG.md b/CHANGELOG.md index 201929ec11c..920d397add7 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -3432,6 +3432,7 @@ Released 2018-09-13 [`absurd_extreme_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#absurd_extreme_comparisons +[`alloc_instead_of_core`]: https://rust-lang.github.io/rust-clippy/master/index.html#alloc_instead_of_core [`allow_attributes_without_reason`]: https://rust-lang.github.io/rust-clippy/master/index.html#allow_attributes_without_reason [`almost_complete_letter_range`]: https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_letter_range [`almost_swapped`]: https://rust-lang.github.io/rust-clippy/master/index.html#almost_swapped @@ -3901,6 +3902,8 @@ Released 2018-09-13 [`skip_while_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#skip_while_next [`slow_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#slow_vector_initialization [`stable_sort_primitive`]: https://rust-lang.github.io/rust-clippy/master/index.html#stable_sort_primitive +[`std_instead_of_alloc`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_alloc +[`std_instead_of_core`]: https://rust-lang.github.io/rust-clippy/master/index.html#std_instead_of_core [`str_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#str_to_string [`string_add`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add [`string_add_assign`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add_assign diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index ceb8470657f..91d27bf526d 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -497,6 +497,9 @@ store.register_lints(&[ size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT, slow_vector_initialization::SLOW_VECTOR_INITIALIZATION, stable_sort_primitive::STABLE_SORT_PRIMITIVE, + std_instead_of_core::ALLOC_INSTEAD_OF_CORE, + std_instead_of_core::STD_INSTEAD_OF_ALLOC, + std_instead_of_core::STD_INSTEAD_OF_CORE, strings::STRING_ADD, strings::STRING_ADD_ASSIGN, strings::STRING_FROM_UTF8_AS_BYTES, diff --git a/clippy_lints/src/lib.register_restriction.rs b/clippy_lints/src/lib.register_restriction.rs index 88d43c8989f..43f1c892eb9 100644 --- a/clippy_lints/src/lib.register_restriction.rs +++ b/clippy_lints/src/lib.register_restriction.rs @@ -66,6 +66,9 @@ store.register_group(true, "clippy::restriction", Some("clippy_restriction"), ve LintId::of(shadow::SHADOW_SAME), LintId::of(shadow::SHADOW_UNRELATED), LintId::of(single_char_lifetime_names::SINGLE_CHAR_LIFETIME_NAMES), + LintId::of(std_instead_of_core::ALLOC_INSTEAD_OF_CORE), + LintId::of(std_instead_of_core::STD_INSTEAD_OF_ALLOC), + LintId::of(std_instead_of_core::STD_INSTEAD_OF_CORE), LintId::of(strings::STRING_ADD), LintId::of(strings::STRING_SLICE), LintId::of(strings::STRING_TO_STRING), diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 1604d1078ee..4f9db4eb5ae 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -365,6 +365,7 @@ mod single_component_path_imports; mod size_of_in_element_count; mod slow_vector_initialization; mod stable_sort_primitive; +mod std_instead_of_core; mod strings; mod strlen_on_c_strings; mod suspicious_operation_groupings; @@ -915,6 +916,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf: let verbose_bit_mask_threshold = conf.verbose_bit_mask_threshold; store.register_late_pass(move || Box::new(operators::Operators::new(verbose_bit_mask_threshold))); store.register_late_pass(|| Box::new(invalid_utf8_in_unchecked::InvalidUtf8InUnchecked)); + store.register_late_pass(|| Box::new(std_instead_of_core::StdReexports)); // add lints here, do not remove this comment, it's used in `new_lint` } diff --git a/clippy_lints/src/std_instead_of_core.rs b/clippy_lints/src/std_instead_of_core.rs new file mode 100644 index 00000000000..56f2a7bae15 --- /dev/null +++ b/clippy_lints/src/std_instead_of_core.rs @@ -0,0 +1,134 @@ +use clippy_utils::diagnostics::span_lint_and_help; +use rustc_hir::{def::Res, HirId, Path, PathSegment}; +use rustc_lint::{LateContext, LateLintPass, Lint}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::{sym, symbol::kw, Symbol}; + +declare_clippy_lint! { + /// ### What it does + /// + /// Finds items imported through `std` when available through `core`. + /// + /// ### Why is this bad? + /// + /// Crates which have `no_std` compatibility may wish to ensure types are imported from core to ensure + /// disabling `std` does not cause the crate to fail to compile. This lint is also useful for crates + /// migrating to become `no_std` compatible. + /// + /// ### Example + /// ```rust + /// use std::hash::Hasher; + /// ``` + /// Use instead: + /// ```rust + /// use core::hash::Hasher; + /// ``` + #[clippy::version = "1.64.0"] + pub STD_INSTEAD_OF_CORE, + restriction, + "type is imported from std when available in core" +} + +declare_clippy_lint! { + /// ### What it does + /// + /// Finds items imported through `std` when available through `alloc`. + /// + /// ### Why is this bad? + /// + /// Crates which have `no_std` compatibility and require alloc may wish to ensure types are imported from + /// alloc to ensure disabling `std` does not cause the crate to fail to compile. This lint is also useful + /// for crates migrating to become `no_std` compatible. + /// + /// ### Example + /// ```rust + /// use std::vec::Vec; + /// ``` + /// Use instead: + /// ```rust + /// # extern crate alloc; + /// use alloc::vec::Vec; + /// ``` + #[clippy::version = "1.64.0"] + pub STD_INSTEAD_OF_ALLOC, + restriction, + "type is imported from std when available in alloc" +} + +declare_clippy_lint! { + /// ### What it does + /// + /// Finds items imported through `alloc` when available through `core`. + /// + /// ### Why is this bad? + /// + /// Crates which have `no_std` compatibility and may optionally require alloc may wish to ensure types are + /// imported from alloc to ensure disabling `alloc` does not cause the crate to fail to compile. This lint + /// is also useful for crates migrating to become `no_std` compatible. + /// + /// ### Example + /// ```rust + /// # extern crate alloc; + /// use alloc::slice::from_ref; + /// ``` + /// Use instead: + /// ```rust + /// use core::slice::from_ref; + /// ``` + #[clippy::version = "1.64.0"] + pub ALLOC_INSTEAD_OF_CORE, + restriction, + "type is imported from alloc when available in core" +} + +declare_lint_pass!(StdReexports => [STD_INSTEAD_OF_CORE, STD_INSTEAD_OF_ALLOC, ALLOC_INSTEAD_OF_CORE]); + +impl<'tcx> LateLintPass<'tcx> for StdReexports { + fn check_path(&mut self, cx: &LateContext<'tcx>, path: &Path<'tcx>, _: HirId) { + // std_instead_of_core + check_path(cx, path, sym::std, sym::core, STD_INSTEAD_OF_CORE); + // std_instead_of_alloc + check_path(cx, path, sym::std, sym::alloc, STD_INSTEAD_OF_ALLOC); + // alloc_instead_of_core + check_path(cx, path, sym::alloc, sym::core, ALLOC_INSTEAD_OF_CORE); + } +} + +fn check_path(cx: &LateContext<'_>, path: &Path<'_>, krate: Symbol, suggested_crate: Symbol, lint: &'static Lint) { + if_chain! { + // check if path resolves to the suggested crate. + if let Res::Def(_, def_id) = path.res; + if suggested_crate == cx.tcx.crate_name(def_id.krate); + + // check if the first segment of the path is the crate we want to identify + if let Some(path_root_segment) = get_first_segment(path); + + // check if the path matches the crate we want to suggest the other path for. + if krate == path_root_segment.ident.name; + then { + span_lint_and_help( + cx, + lint, + path.span, + &format!("used import from `{}` instead of `{}`", krate, suggested_crate), + None, + &format!("consider importing the item from `{}`", suggested_crate), + ); + } + } +} + +/// Returns the first named segment of a [`Path`]. +/// +/// If this is a global path (such as `::std::fmt::Debug`), then the segment after [`kw::PathRoot`] +/// is returned. +fn get_first_segment<'tcx>(path: &Path<'tcx>) -> Option<&'tcx PathSegment<'tcx>> { + let segment = path.segments.first()?; + + // A global path will have PathRoot as the first segment. In this case, return the segment after. + if segment.ident.name == kw::PathRoot { + path.segments.get(1) + } else { + Some(segment) + } +} diff --git a/tests/ui/std_instead_of_core.rs b/tests/ui/std_instead_of_core.rs new file mode 100644 index 00000000000..74f05ec1f65 --- /dev/null +++ b/tests/ui/std_instead_of_core.rs @@ -0,0 +1,39 @@ +#![warn(clippy::std_instead_of_core)] +#![allow(unused_imports)] + +extern crate alloc; + +#[warn(clippy::std_instead_of_core)] +fn std_instead_of_core() { + // Regular import + use std::hash::Hasher; + // Absolute path + use ::std::hash::Hash; + + // Multiple imports + use std::fmt::{Debug, Result}; + + // Function calls + let ptr = std::ptr::null::(); + let ptr_mut = ::std::ptr::null_mut::(); + + // Types + let cell = std::cell::Cell::new(8u32); + let cell_absolute = ::std::cell::Cell::new(8u32); +} + +#[warn(clippy::std_instead_of_alloc)] +fn std_instead_of_alloc() { + use std::vec::Vec; +} + +#[warn(clippy::alloc_instead_of_core)] +fn alloc_instead_of_core() { + use alloc::slice::from_ref; +} + +fn main() { + std_instead_of_core(); + std_instead_of_alloc(); + alloc_instead_of_core(); +} diff --git a/tests/ui/std_instead_of_core.stderr b/tests/ui/std_instead_of_core.stderr new file mode 100644 index 00000000000..9f1644835c1 --- /dev/null +++ b/tests/ui/std_instead_of_core.stderr @@ -0,0 +1,85 @@ +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:9:9 + | +LL | use std::hash::Hasher; + | ^^^^^^^^^^^^^^^^^ + | + = note: `-D clippy::std-instead-of-core` implied by `-D warnings` + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:11:9 + | +LL | use ::std::hash::Hash; + | ^^^^^^^^^^^^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:14:20 + | +LL | use std::fmt::{Debug, Result}; + | ^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:14:27 + | +LL | use std::fmt::{Debug, Result}; + | ^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:17:15 + | +LL | let ptr = std::ptr::null::(); + | ^^^^^^^^^^^^^^^^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:18:19 + | +LL | let ptr_mut = ::std::ptr::null_mut::(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:21:16 + | +LL | let cell = std::cell::Cell::new(8u32); + | ^^^^^^^^^^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `core` + --> $DIR/std_instead_of_core.rs:22:25 + | +LL | let cell_absolute = ::std::cell::Cell::new(8u32); + | ^^^^^^^^^^^^^^^^^ + | + = help: consider importing the item from `core` + +error: used import from `std` instead of `alloc` + --> $DIR/std_instead_of_core.rs:27:9 + | +LL | use std::vec::Vec; + | ^^^^^^^^^^^^^ + | + = note: `-D clippy::std-instead-of-alloc` implied by `-D warnings` + = help: consider importing the item from `alloc` + +error: used import from `alloc` instead of `core` + --> $DIR/std_instead_of_core.rs:32:9 + | +LL | use alloc::slice::from_ref; + | ^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `-D clippy::alloc-instead-of-core` implied by `-D warnings` + = help: consider importing the item from `core` + +error: aborting due to 10 previous errors +