new lint: use_crate_prefix_for_self_imports

CHANGELOG.md

@@ -6115,6 +6115,7 @@ Released 2018-09-13
 [`unwrap_or_else_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_or_else_default
 [`unwrap_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_used
 [`upper_case_acronyms`]: https://rust-lang.github.io/rust-clippy/master/index.html#upper_case_acronyms
+[`use_crate_prefix_for_self_imports`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_crate_prefix_for_self_imports
 [`use_debug`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_debug
 [`use_self`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_self
 [`used_underscore_binding`]: https://rust-lang.github.io/rust-clippy/master/index.html#used_underscore_binding

clippy_config/src/lib.rs

@@ -27,5 +27,5 @@ mod metadata;
 pub mod msrvs;
 pub mod types;
 
-pub use conf::{Conf, get_configuration_metadata, lookup_conf_file, sanitize_explanation};
-pub use metadata::ClippyConfiguration;
+pub use crate::conf::{Conf, get_configuration_metadata, lookup_conf_file, sanitize_explanation};
+pub use crate::metadata::ClippyConfiguration;

clippy_lints/src/declared_lints.rs

@@ -765,6 +765,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::unwrap::UNNECESSARY_UNWRAP_INFO,
     crate::unwrap_in_result::UNWRAP_IN_RESULT_INFO,
     crate::upper_case_acronyms::UPPER_CASE_ACRONYMS_INFO,
+    crate::use_crate_prefix_for_self_imports::USE_CRATE_PREFIX_FOR_SELF_IMPORTS_INFO,
     crate::use_self::USE_SELF_INFO,
     crate::useless_conversion::USELESS_CONVERSION_INFO,
     crate::vec::USELESS_VEC_INFO,

clippy_lints/src/lib.rs

@@ -384,6 +384,7 @@ mod unused_unit;
 mod unwrap;
 mod unwrap_in_result;
 mod upper_case_acronyms;
+mod use_crate_prefix_for_self_imports;
 mod use_self;
 mod useless_conversion;
 mod vec;
@@ -397,11 +398,11 @@ mod zero_sized_map_values;
 mod zombie_processes;
 // end lints modules, do not remove this comment, it’s used in `update_lints`
 
+use crate::utils::attr_collector::{AttrCollector, AttrStorage};
 use clippy_config::{Conf, get_configuration_metadata, sanitize_explanation};
 use clippy_utils::macros::FormatArgsStorage;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_lint::{Lint, LintId};
-use utils::attr_collector::{AttrCollector, AttrStorage};
 
 /// Register all pre expansion lints
 ///
@@ -468,7 +469,7 @@ pub(crate) enum LintCategory {
 }
 
 #[allow(clippy::enum_glob_use)]
-use LintCategory::*;
+use crate::LintCategory::*;
 
 impl LintCategory {
     fn is_all(self) -> bool {
@@ -963,5 +964,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(|_| Box::new(manual_ignore_case_cmp::ManualIgnoreCaseCmp));
     store.register_late_pass(|_| Box::new(unnecessary_literal_bound::UnnecessaryLiteralBound));
     store.register_late_pass(move |_| Box::new(arbitrary_source_item_ordering::ArbitrarySourceItemOrdering::new(conf)));
+    store.register_late_pass(|_| Box::new(use_crate_prefix_for_self_imports::UseCratePrefixForSelfImports));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }

clippy_lints/src/use_crate_prefix_for_self_imports.rs

@@ -0,0 +1,88 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_opt;
+use def_id::LOCAL_CRATE;
+use rustc_errors::Applicability;
+use rustc_hir::def::Res;
+use rustc_hir::{Item, ItemKind, def_id};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_session::declare_lint_pass;
+use rustc_span::{FileName, RealFileName};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// This lint checks for imports from the current crate that do not use the `crate::` prefix.
+    /// It suggests using `crate::` to make it clear that the item is from the same crate.
+    ///
+    /// ### Why is this bad?
+    /// When imports from the current crate lack the `crate::` prefix, it can make the code less readable
+    /// because it’s not immediately clear if the imported item is from the current crate or an external dependency.
+    /// Using `crate::` for self-imports provides a consistent style, making the origin of each import clear.
+    /// This helps reduce confusion and maintain a uniform codebase.
+    ///
+    /// ### Example
+    /// ```rust,ignore
+    /// // lib.rs
+    /// mod foo;
+    /// use foo::bar;
+    /// ```
+    ///
+    /// ```rust,ignore
+    /// // foo.rs
+    /// #[path = "./foo.rs"]
+    /// pub fn bar() {}
+    /// ```
+    ///
+    /// Use instead:
+    /// ```rust,ignore
+    /// // lib.rs
+    /// mod foo;
+    /// use crate::foo::bar;
+    /// ```
+    ///
+    /// ```rust,ignore
+    /// // foo.rs
+    /// #[path = "./foo.rs"]
+    /// pub fn bar() {}
+    /// ```
+    #[clippy::version = "1.84.0"]
+    pub USE_CRATE_PREFIX_FOR_SELF_IMPORTS,
+    style,
+    "checks that imports from the current crate use the `crate::` prefix"
+}
+
+declare_lint_pass!(UseCratePrefixForSelfImports => [USE_CRATE_PREFIX_FOR_SELF_IMPORTS]);
+
+impl LateLintPass<'_> for UseCratePrefixForSelfImports {
+    fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
+        let FileName::Real(RealFileName::LocalPath(p)) = cx.sess().source_map().span_to_filename(item.span) else {
+            return;
+        };
+        let Some(file_name) = p.file_name() else {
+            return;
+        };
+        // only check `main.rs` and `lib.rs`
+        if !(file_name == "main.rs" || file_name == "lib.rs") {
+            return;
+        }
+
+        if let ItemKind::Use(use_path, _) = &item.kind {
+            if let Some(segment) = use_path.segments.first()
+                && let Res::Def(_, def_id) = segment.res
+                && def_id.krate == LOCAL_CRATE
+            {
+                let root = segment.ident.name;
+                if root != rustc_span::symbol::kw::Crate && root != rustc_span::symbol::kw::Super {
+                    span_lint_and_sugg(
+                        cx,
+                        USE_CRATE_PREFIX_FOR_SELF_IMPORTS,
+                        segment.ident.span,
+                        "this import is not clear",
+                        "prefix with `crate::`",
+                        format!("crate::{}", snippet_opt(cx, segment.ident.span).unwrap()),
+                        Applicability::MachineApplicable,
+                    );
+                }
+            }
+        }
+    }
+}

clippy_utils/src/lib.rs

@@ -110,6 +110,7 @@ use rustc_hir::{
 };
 use rustc_lexer::{TokenKind, tokenize};
 use rustc_lint::{LateContext, Level, Lint, LintContext};
+use rustc_middle::hir::nested_filter;
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::Const;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
@@ -124,13 +125,11 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{Ident, Symbol, kw};
 use rustc_span::{InnerSpan, Span, sym};
 use rustc_target::abi::Integer;
-use visitors::Visitable;
 
 use crate::consts::{ConstEvalCtxt, Constant, mir_to_const};
 use crate::higher::Range;
 use crate::ty::{adt_and_variant_of_res, can_partially_move_ty, expr_sig, is_copy, is_recursively_primitive_type};
-use crate::visitors::for_each_expr_without_closures;
-use rustc_middle::hir::nested_filter;
+use crate::visitors::{Visitable, for_each_expr_without_closures};
 
 #[macro_export]
 macro_rules! extract_msrv_attr {

tests/ui-cargo/use_crate_prefix_for_self_imports/fail/Cargo.stderr

@@ -0,0 +1,10 @@
+error: this import is not clear
+ --> src/main.rs:1:5
+  |
+1 | use foo::Foo;
+  |     ^^^ help: prefix with `crate::`: `crate::foo`
+  |
+  = note: `-D clippy::use-crate-prefix-for-self-imports` implied by `-D warnings`
+  = help: to override `-D warnings` add `#[allow(clippy::use_crate_prefix_for_self_imports)]`
+
+error: could not compile `fail` (bin "fail") due to 1 previous error

tests/ui-cargo/use_crate_prefix_for_self_imports/fail/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "fail"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

tests/ui-cargo/use_crate_prefix_for_self_imports/fail/src/foo.rs

@@ -0,0 +1 @@
+pub struct Foo;

tests/ui-cargo/use_crate_prefix_for_self_imports/fail/src/main.rs

@@ -0,0 +1,7 @@
+use foo::Foo;
+
+mod foo;
+
+fn main() {
+    let _foo = Foo;
+}

tests/ui-cargo/use_crate_prefix_for_self_imports/pass/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "pass"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

tests/ui-cargo/use_crate_prefix_for_self_imports/pass/src/foo.rs

@@ -0,0 +1 @@
+pub struct Foo;

tests/ui-cargo/use_crate_prefix_for_self_imports/pass/src/main.rs

@@ -0,0 +1,7 @@
+use crate::foo::Foo;
+
+mod foo;
+
+fn main() {
+    let _foo = Foo;
+}

tests/ui/use_crate_prefix_for_self_imports.rs

@@ -0,0 +1,5 @@
+#![warn(clippy::use_crate_prefix_for_self_imports)]
+
+fn main() {
+    // test code goes here
+}