Refactor absolute_paths:

* Check the path length first
* Use `is_from_proc_macro`
* Use symbols instead of strings when checking crate names

clippy_lints/src/absolute_paths.rs

@@ -1,6 +1,6 @@
 use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint;
-use clippy_utils::source::snippet_opt;
+use clippy_utils::is_from_proc_macro;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
@@ -8,6 +8,7 @@ use rustc_hir::{HirId, ItemKind, Node, Path};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::impl_lint_pass;
 use rustc_span::symbol::kw;
+use rustc_span::Symbol;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -24,6 +25,13 @@ declare_clippy_lint! {
     /// Note: One exception to this is code from macro expansion - this does not lint such cases, as
     /// using absolute paths is the proper way of referencing items in one.
     ///
+    /// ### Known issues
+    ///
+    /// There are currently a few cases which are not caught by this lint:
+    /// * Macro calls. e.g. `path::to::macro!()`
+    /// * Derive macros. e.g. `#[derive(path::to::macro)]`
+    /// * Attribute macros. e.g. `#[path::to::macro]`
+    ///
     /// ### Example
     /// ```no_run
     /// let x = std::f64::consts::PI;
@@ -48,56 +56,60 @@ impl_lint_pass!(AbsolutePaths => [ABSOLUTE_PATHS]);
 
 pub struct AbsolutePaths {
     pub absolute_paths_max_segments: u64,
-    pub absolute_paths_allowed_crates: &'static FxHashSet<String>,
+    pub absolute_paths_allowed_crates: FxHashSet<Symbol>,
 }
 
 impl AbsolutePaths {
     pub fn new(conf: &'static Conf) -> Self {
         Self {
             absolute_paths_max_segments: conf.absolute_paths_max_segments,
-            absolute_paths_allowed_crates: &conf.absolute_paths_allowed_crates,
+            absolute_paths_allowed_crates: conf
+                .absolute_paths_allowed_crates
+                .iter()
+                .map(|x| Symbol::intern(x))
+                .collect(),
         }
     }
 }
 
-impl LateLintPass<'_> for AbsolutePaths {
+impl<'tcx> LateLintPass<'tcx> for AbsolutePaths {
     // We should only lint `QPath::Resolved`s, but since `Path` is only used in `Resolved` and `UsePath`
     // we don't need to use a visitor or anything as we can just check if the `Node` for `hir_id` isn't
     // a `Use`
-    #[expect(clippy::cast_possible_truncation)]
-    fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, hir_id: HirId) {
-        let Self {
-            absolute_paths_max_segments,
-            absolute_paths_allowed_crates,
-        } = self;
-
-        if !path.span.from_expansion()
-            && let node = cx.tcx.hir_node(hir_id)
-            && !matches!(node, Node::Item(item) if matches!(item.kind, ItemKind::Use(_, _)))
-            && let [first, rest @ ..] = path.segments
-            // Handle `::std`
-            && let (segment, len) = if first.ident.name == kw::PathRoot {
-                // Indexing is fine as `PathRoot` must be followed by another segment. `len() - 1`
-                // is fine here for the same reason
-                (&rest[0], path.segments.len() - 1)
+    fn check_path(&mut self, cx: &LateContext<'tcx>, path: &Path<'tcx>, hir_id: HirId) {
+        let segments = match path.segments {
+            [] | [_] => return,
+            // Don't count enum variants and trait items as part of the length.
+            [rest @ .., _]
+                if let [.., s] = rest
+                    && matches!(s.res, Res::Def(DefKind::Enum | DefKind::Trait | DefKind::TraitAlias, _)) =>
+            {
+                rest
+            },
+            path => path,
+        };
+        if let [s1, s2, ..] = segments
+            && let has_root = s1.ident.name == kw::PathRoot
+            && let first = if has_root { s2 } else { s1 }
+            && let len = segments.len() - usize::from(has_root)
+            && len as u64 > self.absolute_paths_max_segments
+            && let crate_name = if let Res::Def(DefKind::Mod, DefId { index, .. }) = first.res
+                && index == CRATE_DEF_INDEX
+            {
+                // `other_crate::foo` or `::other_crate::foo`
+                first.ident.name
+            } else if first.ident.name == kw::Crate || has_root {
+                // `::foo` or `crate::foo`
+                kw::Crate
             } else {
-                (first, path.segments.len())
-            }
-            && len > *absolute_paths_max_segments as usize
-            && let Some(segment_snippet) = snippet_opt(cx, segment.ident.span)
-            && segment_snippet == segment.ident.as_str()
-        {
-            let is_abs_external =
-                matches!(segment.res, Res::Def(DefKind::Mod, DefId { index, .. }) if index == CRATE_DEF_INDEX);
-            let is_abs_crate = segment.ident.name == kw::Crate;
-
-            if is_abs_external && absolute_paths_allowed_crates.contains(segment.ident.name.as_str())
-                || is_abs_crate && absolute_paths_allowed_crates.contains("crate")
-            {
                 return;
             }
-
-            if is_abs_external || is_abs_crate {
+            && !path.span.from_expansion()
+            && let node = cx.tcx.hir_node(hir_id)
+            && !matches!(node, Node::Item(item) if matches!(item.kind, ItemKind::Use(..)))
+            && !self.absolute_paths_allowed_crates.contains(&crate_name)
+            && !is_from_proc_macro(cx, path)
+        {
             span_lint(
                 cx,
                 ABSOLUTE_PATHS,
@@ -107,4 +119,3 @@ impl LateLintPass<'_> for AbsolutePaths {
         }
     }
 }
-}

clippy_utils/src/check_proc_macro.rs

@@ -123,16 +123,14 @@ fn qpath_search_pat(path: &QPath<'_>) -> (Pat, Pat) {
 
 fn path_search_pat(path: &Path<'_>) -> (Pat, Pat) {
     let (head, tail) = match path.segments {
-        [head, .., tail] => (head, tail),
-        [p] => (p, p),
         [] => return (Pat::Str(""), Pat::Str("")),
+        [p] => (Pat::Sym(p.ident.name), p),
+        // QPath::Resolved can have a path that looks like `<Foo as Bar>::baz` where
+        // the path (`Bar::baz`) has it's span covering the whole QPath.
+        [.., tail] => (Pat::Str(""), tail),
     };
     (
-        if head.ident.name == kw::PathRoot {
-            Pat::Str("::")
-        } else {
-            Pat::Sym(head.ident.name)
-        },
+        head,
         if tail.args.is_some() {
             Pat::Str(">")
         } else {

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

@@ -1,29 +1,44 @@
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:40:5
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:14:13
    |
-LL |     std::f32::MAX;
-   |     ^^^^^^^^^^^^^
+LL |     let _ = std::path::is_separator(' ');
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `-D clippy::absolute-paths` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::absolute_paths)]`
+note: the lint level is defined here
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:7:9
+   |
+LL | #![deny(clippy::absolute_paths)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:41:5
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:20:13
    |
-LL |     core::f32::MAX;
-   |     ^^^^^^^^^^^^^^
+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:42:5
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:25:13
    |
-LL |     ::core::f32::MAX;
-   |     ^^^^^^^^^^^^^^^^
+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:58:5
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:31
    |
-LL |     ::std::f32::MAX;
+LL |     let _: &std::path::Path = std::path::Path::new("");
    |                               ^^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:28:13
+   |
+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
+   |
+LL |     let _ = std::option::Option::None::<i32>;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
 

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

@@ -0,0 +1,14 @@
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:25:13
+   |
+LL |     let _ = std::collections::hash_map::HashMap::<i32, i32>::new();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:7:9
+   |
+LL | #![deny(clippy::absolute_paths)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

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

@@ -0,0 +1,80 @@
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:14:13
+   |
+LL |     let _ = std::path::is_separator(' ');
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:7:9
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+LL |     crate::m1::S
+   |     ^^^^^^^^^^^^
+
+error: aborting due to 12 previous errors
+

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

@@ -1,71 +0,0 @@
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:40:5
-   |
-LL |     std::f32::MAX;
-   |     ^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::absolute-paths` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::absolute_paths)]`
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:41:5
-   |
-LL |     core::f32::MAX;
-   |     ^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:42:5
-   |
-LL |     ::core::f32::MAX;
-   |     ^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:43:5
-   |
-LL |     crate::a::b::c::C;
-   |     ^^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:44:5
-   |
-LL |     crate::a::b::c::d::e::f::F;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:45:5
-   |
-LL |     crate::a::A;
-   |     ^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:46:5
-   |
-LL |     crate::a::b::B;
-   |     ^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:47:5
-   |
-LL |     crate::a::b::c::C::ZERO;
-   |     ^^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:48:5
-   |
-LL |     helper::b::c::d::e::f();
-   |     ^^^^^^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:49:5
-   |
-LL |     ::helper::b::c::d::e::f();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^
-
-error: consider bringing this path into scope with the `use` keyword
-  --> tests/ui-toml/absolute_paths/absolute_paths.rs:58:5
-   |
-LL |     ::std::f32::MAX;
-   |     ^^^^^^^^^^^^^^^
-
-error: aborting due to 11 previous errors
-

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

@@ -0,0 +1,98 @@
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:14:13
+   |
+LL |     let _ = std::path::is_separator(' ');
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:7:9
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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
+   |
+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:113:14
+   |
+LL | pub const _: crate::S = {
+   |              ^^^^^^^^
+
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:114:9
+   |
+LL |     let crate::S = m1::S;
+   |         ^^^^^^^^
+
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:116:5
+   |
+LL |     crate::m1::S
+   |     ^^^^^^^^^^^^
+
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths.rs:122:14
+   |
+LL |     let _ = <crate::S as Clone>::clone(&m1::S);
+   |              ^^^^^^^^
+
+error: aborting due to 15 previous errors
+

tests/ui-toml/absolute_paths/absolute_paths.rs

@@ -1,97 +1,123 @@
 //@aux-build:../../ui/auxiliary/proc_macros.rs
-//@aux-build:helper.rs
-//@revisions: allow_crates disallow_crates
+//@revisions: default allow_crates allow_long no_short
+//@[default] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/default
 //@[allow_crates] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/allow_crates
-//@[disallow_crates] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/disallow_crates
-#![allow(clippy::no_effect, clippy::legacy_numeric_constants, unused)]
-#![warn(clippy::absolute_paths)]
-#![feature(decl_macro)]
+//@[allow_long] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/allow_long
+//@[no_short] rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/no_short
+#![deny(clippy::absolute_paths)]
 
-extern crate helper;
-#[macro_use]
 extern crate proc_macros;
+use proc_macros::{external, inline_macros, with_span};
 
-pub mod a {
-    pub mod b {
-        pub mod c {
-            pub struct C;
-
-            impl C {
-                pub const ZERO: u32 = 0;
-            }
-
-            pub mod d {
-                pub mod e {
-                    pub mod f {
-                        pub struct F;
-                    }
-                }
-            }
-        }
-
-        pub struct B;
-    }
-
-    pub struct A;
-}
-
+#[inline_macros]
 fn main() {
-    f32::max(1.0, 2.0);
-    std::f32::MAX;
-    core::f32::MAX;
-    ::core::f32::MAX;
-    crate::a::b::c::C;
-    crate::a::b::c::d::e::f::F;
-    crate::a::A;
-    crate::a::b::B;
-    crate::a::b::c::C::ZERO;
-    helper::b::c::d::e::f();
-    ::helper::b::c::d::e::f();
-    fn b() -> a::b::B {
-        todo!()
-    }
-    std::println!("a");
-    let x = 1;
-    std::ptr::addr_of!(x);
-    // Test we handle max segments with `PathRoot` properly; this has 4 segments but we should say it
-    // has 3
-    ::std::f32::MAX;
-    // Do not lint due to the above
-    ::helper::a();
-    // Do not lint
-    helper::a();
-    use crate::a::b::c::C;
-    use a::b;
-    use std::f32::MAX;
-    a::b::c::d::e::f::F;
-    b::c::C;
-    fn a() -> a::A {
-        todo!()
-    }
-    use a::b::c;
+    let _ = std::path::is_separator(' ');
+    //~[default]^ absolute_paths
+    //~[allow_crates]| absolute_paths
+    //~[no_short]| absolute_paths
 
-    fn c() -> c::C {
-        todo!()
+    // Make sure this is treated as having three path segments, not four.
+    let _ = ::std::path::MAIN_SEPARATOR;
+    //~[default]^ absolute_paths
+    //~[allow_crates]| absolute_paths
+    //~[no_short]| absolute_paths
+
+    let _ = std::collections::hash_map::HashMap::<i32, i32>::new(); //~ absolute_paths
+
+    // Note `std::path::Path::new` is treated as having three parts
+    let _: &std::path::Path = std::path::Path::new("");
+    //~[default]^ absolute_paths
+    //~[default]| absolute_paths
+    //~[allow_crates]| absolute_paths
+    //~[allow_crates]| absolute_paths
+    //~[no_short]| absolute_paths
+    //~[no_short]| absolute_paths
+
+    // Treated as having three parts.
+    let _ = ::core::clone::Clone::clone(&0i32);
+    //~[default]^ absolute_paths
+    //~[no_short]| absolute_paths
+    let _ = <i32 as core::clone::Clone>::clone(&0i32);
+    //~[default]^ absolute_paths
+    //~[no_short]| absolute_paths
+    let _ = std::option::Option::None::<i32>;
+    //~[default]^ absolute_paths
+    //~[allow_crates]| absolute_paths
+    //~[no_short]| absolute_paths
+
+    {
+        // FIXME: macro calls should be checked.
+        let x = 1i32;
+        let _ = core::ptr::addr_of!(x);
     }
-    fn d() -> Result<(), ()> {
-        todo!()
+
+    {
+        // FIXME: derive macro paths should be checked.
+        #[derive(core::clone::Clone)]
+        struct S;
     }
-    external! {
-        crate::a::b::c::C::ZERO;
+
+    {
+        use core::fmt;
+        use core::marker::PhantomData;
+
+        struct X<T>(PhantomData<T>);
+        impl<T: core::cmp::Eq> core::fmt::Display for X<T>
+        //~[default]^ absolute_paths
+        //~[default]| absolute_paths
+        //~[no_short]| absolute_paths
+        //~[no_short]| absolute_paths
+        where T: core::clone::Clone
+        //~[no_short]^ absolute_paths
+        //~[default]| absolute_paths
+        {
+            fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
+                Ok(())
             }
-    // For some reason, `path.span.from_expansion()` takes care of this for us
+        }
+    }
+
+    {
+        mod m1 {
+            pub(crate) mod m2 {
+                pub(crate) const FOO: i32 = 0;
+            }
+        }
+        let _ = m1::m2::FOO;
+    }
+
     with_span! {
         span
-        crate::a::b::c::C::ZERO;
+        let _ = std::path::is_separator(' ');
     }
-    macro_rules! local_crate {
-        () => {
-            crate::a::b::c::C::ZERO;
+
+    external! {
+        let _ = std::path::is_separator(' ');
+    }
+
+    inline! {
+        let _ = std::path::is_separator(' ');
+    }
+}
+
+pub use core::cmp::Ordering;
+pub use std::fs::File;
+
+#[derive(Clone)]
+pub struct S;
+mod m1 {
+    pub use crate::S;
+}
+
+//~[no_short]v absolute_paths
+pub const _: crate::S = {
+    let crate::S = m1::S; //~[no_short] absolute_paths
+
+    crate::m1::S
+    //~[default]^ absolute_paths
+    //~[no_short]| absolute_paths
 };
-    }
-    macro local_crate_2_0() {
-        crate::a::b::c::C::ZERO;
-    }
-    local_crate!();
-    local_crate_2_0!();
+
+pub fn f() {
+    let _ = <crate::S as Clone>::clone(&m1::S); //~[no_short] absolute_paths
 }

tests/ui-toml/absolute_paths/absolute_paths_2015.default.stderr

@@ -0,0 +1,14 @@
+error: consider bringing this path into scope with the `use` keyword
+  --> tests/ui-toml/absolute_paths/absolute_paths_2015.rs:15:13
+   |
+LL |     let _ = ::m1::m2::X;
+   |             ^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> tests/ui-toml/absolute_paths/absolute_paths_2015.rs:6:9
+   |
+LL | #![deny(clippy::absolute_paths)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui-toml/absolute_paths/absolute_paths_2015.rs

@@ -0,0 +1,16 @@
+//@revisions: default allow_crates
+//@[default]rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/default
+//@[allow_crates]rustc-env:CLIPPY_CONF_DIR=tests/ui-toml/absolute_paths/allow_crates
+//@edition:2015
+
+#![deny(clippy::absolute_paths)]
+
+mod m1 {
+    pub mod m2 {
+        pub struct X;
+    }
+}
+
+fn main() {
+    let _ = ::m1::m2::X; //~[default] absolute_paths
+}

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

@@ -1,2 +1 @@
-absolute-paths-max-segments = 2
-absolute-paths-allowed-crates = ["crate", "helper"]
+absolute-paths-allowed-crates = ["core", "crate"]

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

@@ -0,0 +1 @@
+absolute-paths-max-segments = 3

tests/ui-toml/absolute_paths/auxiliary/helper.rs

@@ -1,11 +0,0 @@
-pub fn a() {}
-
-pub mod b {
-    pub mod c {
-        pub mod d {
-            pub mod e {
-                pub fn f() {}
-            }
-        }
-    }
-}

tests/ui-toml/absolute_paths/disallow_crates/clippy.toml

@@ -1 +0,0 @@
-absolute-paths-max-segments = 2

tests/ui-toml/absolute_paths/no_short/clippy.toml

@@ -0,0 +1 @@
+absolute-paths-max-segments = 0