Add relative_path_in_macro_definition lint (#14472) #14645

CHANGELOG.md

@@ -5,6 +5,9 @@ See [Changelog Update](book/src/development/infrastructure/changelog_update.md)
 document.
 
 ## Unreleased / Beta / In Rust Nightly
+### New Lints
+- **`relative_path_in_macro_definition`**:
+  Warns about relative paths to `core` or `kernel` in macro definitions, recommending absolute paths to avoid ambiguity.
 
 [1e5237f4...master](https://github.com/rust-lang/rust-clippy/compare/1e5237f4...master)
 
@@ -6226,6 +6229,7 @@ Released 2018-09-13
 [`ref_patterns`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_patterns
 [`regex_creation_in_loops`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_creation_in_loops
 [`regex_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_macro
+[`relative_path_in_macro_definition`]: https://rust-lang.github.io/rust-clippy/master/index.html#relative_path_in_macro_definition
 [`renamed_function_params`]: https://rust-lang.github.io/rust-clippy/master/index.html#renamed_function_params
 [`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

clippy_config/src/conf.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use crate::ClippyConfiguration;
 use crate::types::{
     DisallowedPath, DisallowedPathWithoutReplacement, MacroMatcher, MatchLintBehaviour, PubUnderscoreFieldsBehaviour,

clippy_config/src/types.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use clippy_utils::paths::{PathNS, find_crates, lookup_path};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{Applicability, Diag};

clippy_lints/src/declare_clippy_lint.rs

@@ -1,3 +1,4 @@
+#![allow(clippy::relative_path_in_macro_definition)]
 #[macro_export]
 #[allow(clippy::crate_in_macro_def)]
 macro_rules! declare_clippy_lint {

clippy_lints/src/declared_lints.rs

@@ -648,6 +648,7 @@ pub static LINTS: &[&crate::LintInfo] = &[
     crate::regex::INVALID_REGEX_INFO,
     crate::regex::REGEX_CREATION_IN_LOOPS_INFO,
     crate::regex::TRIVIAL_REGEX_INFO,
+    crate::relative_path_in_macro_definition::RELATIVE_PATH_IN_MACRO_DEFINITION_INFO,
     crate::repeat_vec_with_capacity::REPEAT_VEC_WITH_CAPACITY_INFO,
     crate::reserve_after_initialization::RESERVE_AFTER_INITIALIZATION_INFO,
     crate::return_self_not_must_use::RETURN_SELF_NOT_MUST_USE_INFO,

clippy_lints/src/deprecated_lints.rs

@@ -1,5 +1,6 @@
 // This file is managed by `cargo dev rename_lint` and `cargo dev deprecate_lint`.
 // Prefer to use those when possible.
+#![allow(clippy::relative_path_in_macro_definition)]
 
 macro_rules! declare_with_version {
     ($name:ident($name_version:ident) = [$(

clippy_lints/src/lib.rs

@@ -324,6 +324,7 @@ mod ref_option_ref;
 mod ref_patterns;
 mod reference;
 mod regex;
+mod relative_path_in_macro_definition;
 mod repeat_vec_with_capacity;
 mod reserve_after_initialization;
 mod return_self_not_must_use;
@@ -946,5 +947,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(|_| Box::new(single_option_map::SingleOptionMap));
     store.register_late_pass(move |_| Box::new(redundant_test_prefix::RedundantTestPrefix));
     store.register_late_pass(|_| Box::new(cloned_ref_to_slice_refs::ClonedRefToSliceRefs::new(conf)));
+    store.register_early_pass(|| Box::new(relative_path_in_macro_definition::RelativePathInMacroDefinition));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }

clippy_lints/src/missing_asserts_for_indexing.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use std::mem;
 use std::ops::ControlFlow;
 

clippy_lints/src/operators/double_comparison.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::eq_expr_value;
 use clippy_utils::source::snippet_with_applicability;

clippy_lints/src/relative_path_in_macro_definition.rs

@@ -0,0 +1,97 @@
+use clippy_utils::diagnostics::span_lint;
+use rustc_ast::ast::{Item, ItemKind};
+use rustc_ast::token::{Token, TokenKind};
+use rustc_ast::tokenstream::{TokenStream, TokenTree};
+use rustc_lint::{EarlyContext, EarlyLintPass};
+use rustc_session::declare_lint_pass;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks that references to crates in macro definitions use absolute paths.
+    ///
+    /// ### Why is this bad?
+    /// Using relative paths (e.g., `crate_name::...`) in macros can lead to ambiguity if the macro is used in a context
+    /// where a user defines a module with the same name. Absolute paths (e.g., `::crate_name::...`) ensure the macro always refers to the intended crate.
+    ///
+    /// ### Example
+    /// ```rust
+    /// // Bad
+    /// macro_rules! my_macro {
+    ///     () => {
+    ///         std::mem::drop(0);
+    ///     };
+    /// }
+    ///
+    /// // Good
+    /// macro_rules! my_macro {
+    ///     () => {
+    ///         ::std::mem::drop(0);
+    ///     };
+    /// }
+    /// ```
+    #[clippy::version = "1.88.0"]
+    pub RELATIVE_PATH_IN_MACRO_DEFINITION,
+    correctness,
+    "using relative paths in declarative macros can lead to context-dependent behavior"
+}
+
+declare_lint_pass!(RelativePathInMacroDefinition => [RELATIVE_PATH_IN_MACRO_DEFINITION]);
+
+impl EarlyLintPass for RelativePathInMacroDefinition {
+    fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
+        if let ItemKind::MacroDef(_, macro_def) = &item.kind {
+            check_token_stream(cx, &macro_def.body.tokens);
+        }
+    }
+}
+
+fn check_token_stream(cx: &EarlyContext<'_>, tokens: &TokenStream) {
+    let mut iter = tokens.iter().peekable();
+    let mut prev_token: Option<&TokenTree> = None;
+
+    while let Some(tree) = iter.next() {
+        match tree {
+            TokenTree::Token(token, _) => {
+                if let TokenKind::Ident(ident, _) = token.kind {
+                    let first_segment = ident;
+
+                    let is_path_start = iter.peek().is_some_and(|next_tree| {
+                        if let TokenTree::Token(next_token, _) = next_tree {
+                            next_token.kind == TokenKind::PathSep
+                        } else {
+                            false
+                        }
+                    });
+
+                    if is_path_start {
+                        let is_absolute = prev_token.is_some_and(|prev| {
+                            matches!(
+                                prev,
+                                TokenTree::Token(
+                                    Token {
+                                        kind: TokenKind::PathSep,
+                                        ..
+                                    },
+                                    _
+                                )
+                            )
+                        });
+
+                        if !is_absolute {
+                            span_lint(
+                                cx,
+                                RELATIVE_PATH_IN_MACRO_DEFINITION,
+                                token.span,
+                                format!("avoid relative path to `{first_segment}` in macro definitions"),
+                            );
+                        }
+                    }
+                }
+            },
+            TokenTree::Delimited(_open_span, _close_span, _delim, token_stream) => {
+                check_token_stream(cx, token_stream);
+            },
+        }
+        prev_token = Some(tree);
+    }
+}

clippy_lints/src/utils/author.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use clippy_utils::{MaybePath, get_attr, higher, path_def_id, sym};
 use itertools::Itertools;
 use rustc_ast::LitIntType;

clippy_utils/src/check_proc_macro.rs

@@ -11,6 +11,7 @@
 //! must exist at both the start and the end of an item (e.g. an expression or a path) assuming the
 //! code was written, and check if the span contains that text. Note this will only work correctly
 //! if the span is not from a `macro_rules` based macro.
+#![allow(clippy::relative_path_in_macro_definition)]
 
 use rustc_abi::ExternAbi;
 use rustc_ast::AttrStyle;

clippy_utils/src/lib.rs

@@ -8,6 +8,7 @@
 #![feature(array_windows)]
 #![recursion_limit = "512"]
 #![allow(
+    clippy::relative_path_in_macro_definition,
     clippy::missing_errors_doc,
     clippy::missing_panics_doc,
     clippy::must_use_candidate,

clippy_utils/src/macros.rs

@@ -1,4 +1,5 @@
 #![allow(clippy::similar_names)] // `expr` and `expn`
+#![allow(clippy::relative_path_in_macro_definition)]
 
 use std::sync::{Arc, OnceLock};
 

clippy_utils/src/paths.rs

@@ -3,6 +3,7 @@
 //!
 //! Whenever possible, please consider diagnostic items over hardcoded paths.
 //! See <https://github.com/rust-lang/rust-clippy/issues/5393> for more information.
+#![allow(clippy::relative_path_in_macro_definition)]
 
 use crate::{MaybePath, path_def_id, sym};
 use rustc_ast::Mutability;

clippy_utils/src/sugg.rs

@@ -1,5 +1,6 @@
 //! Contains utility functions to generate suggestions.
 #![deny(clippy::missing_docs_in_private_items)]
+#![allow(clippy::relative_path_in_macro_definition)]
 
 use crate::source::{snippet, snippet_opt, snippet_with_applicability, snippet_with_context};
 use crate::ty::expr_sig;

clippy_utils/src/sym.rs

@@ -1,4 +1,5 @@
 #![allow(non_upper_case_globals)]
+#![allow(clippy::relative_path_in_macro_definition)]
 
 use rustc_span::symbol::PREDEFINED_SYMBOLS_COUNT;
 

clippy_utils/src/visitors.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use crate::ty::needs_ordered_drop;
 use crate::{get_enclosing_block, path_to_local_id};
 use core::ops::ControlFlow;

rustc_tools_util/src/lib.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::relative_path_in_macro_definition)]
+
 use std::path::PathBuf;
 use std::process::Command;
 use std::str;

tests/ui-toml/absolute_paths/absolute_paths.allow_crates.stderr

@@ -1,5 +1,5 @@
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:14:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:15:13
    |
 LL |     let _ = std::path::is_separator(' ');
    |             ^^^^^^^^^^^^^^^^^^^^^^^
@@ -11,31 +11,31 @@ LL | #![deny(clippy::absolute_paths)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:20:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:21:13
    |
 LL |     let _ = ::std::path::MAIN_SEPARATOR;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:25:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:26:13
    |
 LL |     let _ = std::collections::hash_map::HashMap::<i32, i32>::new();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:31
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:29:31
    |
 LL |     let _: &std::path::Path = std::path::Path::new("");
    |                               ^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:29:13
    |
 LL |     let _: &std::path::Path = std::path::Path::new("");
    |             ^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:43:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:44:13
    |
 LL |     let _ = std::option::Option::None::<i32>;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/ui-toml/absolute_paths/absolute_paths.allow_long.stderr

@@ -1,5 +1,5 @@
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:25:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:26:13
    |
 LL |     let _ = std::collections::hash_map::HashMap::<i32, i32>::new();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/ui-toml/absolute_paths/absolute_paths.default.stderr

@@ -1,5 +1,5 @@
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:14:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:15:13
    |
 LL |     let _ = std::path::is_separator(' ');
    |             ^^^^^^^^^^^^^^^^^^^^^^^
@@ -11,67 +11,67 @@ LL | #![deny(clippy::absolute_paths)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:20:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:21:13
    |
 LL |     let _ = ::std::path::MAIN_SEPARATOR;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:25:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:26:13
    |
 LL |     let _ = std::collections::hash_map::HashMap::<i32, i32>::new();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:31
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:29:31
    |
 LL |     let _: &std::path::Path = std::path::Path::new("");
    |                               ^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:29:13
    |
 LL |     let _: &std::path::Path = std::path::Path::new("");
    |             ^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:37:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:38:13
    |
 LL |     let _ = ::core::clone::Clone::clone(&0i32);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:40:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:41:13
    |
 LL |     let _ = <i32 as core::clone::Clone>::clone(&0i32);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:43:13
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:44:13
    |
 LL |     let _ = std::option::Option::None::<i32>;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:65:17
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:66:17
    |
 LL |         impl<T: core::cmp::Eq> core::fmt::Display for X<T>
    |                 ^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:70:18
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:71:18
    |
 LL |         where T: core::clone::Clone
    |                  ^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:65:32
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:66:32
    |
 LL |         impl<T: core::cmp::Eq> core::fmt::Display for X<T>
    |                                ^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:116:5
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:117:5
    |
 LL |     crate::m1::S
    |     ^^^^^^^^^^^^