Handle paths with leading :: (root)

Author: Centri3

clippy_lints/src/absolute_symbol_paths.rs

@@ -61,16 +61,24 @@ impl LateLintPass<'_> for AbsoluteSymbolPaths {
         if !path.span.from_expansion()
             && let Some(node) = cx.tcx.hir().find(hir_id)
             && !matches!(node, Node::Item(item) if matches!(item.kind, ItemKind::Use(_, _)))
-            && path.segments.len() > *absolute_symbol_paths_max_segments as usize
-            && let [first, ..] = path.segments
-            && let Some(first_snippet) = snippet_opt(cx, first.ident.span)
-            && first_snippet == first.ident.as_str()
+            && 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. Similarly,
+                // `len() - 1` is fine here for the same reason
+                (&rest[0], path.segments.len() - 1)
+            } else {
+                (first, path.segments.len())
+            }
+            && len > *absolute_symbol_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!(first.res, Res::Def(DefKind::Mod, DefId { index, .. }) if index == CRATE_DEF_INDEX);
-            let is_abs_crate = first.ident.name == kw::Crate;
+                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_symbol_paths_allowed_crates.contains(first.ident.name.as_str())
+            if is_abs_external && absolute_symbol_paths_allowed_crates.contains(segment.ident.name.as_str())
                 || is_abs_crate && absolute_symbol_paths_allowed_crates.contains("crate")
             {
                 return;

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

@@ -12,5 +12,17 @@ error: consider referring to this symbol by adding a `use` statement for consist
 LL |     core::f32::MAX;
    |     ^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: consider referring to this symbol by adding a `use` statement for consistent formatting
+  --> $DIR/absolute_symbol_paths.rs:42:5
+   |
+LL |     ::core::f32::MAX;
+   |     ^^^^^^^^^^^^^^^^
+
+error: consider referring to this symbol by adding a `use` statement for consistent formatting
+  --> $DIR/absolute_symbol_paths.rs:58:5
+   |
+LL |     ::std::f32::MAX;
+   |     ^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
 

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

@@ -15,38 +15,56 @@ LL |     core::f32::MAX;
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
   --> $DIR/absolute_symbol_paths.rs:42:5
    |
+LL |     ::core::f32::MAX;
+   |     ^^^^^^^^^^^^^^^^
+
+error: consider referring to this symbol by adding a `use` statement for consistent formatting
+  --> $DIR/absolute_symbol_paths.rs:43:5
+   |
 LL |     crate::a::b::c::C;
    |     ^^^^^^^^^^^^^^^^^
 
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
-  --> $DIR/absolute_symbol_paths.rs:43:5
+  --> $DIR/absolute_symbol_paths.rs:44:5
    |
 LL |     crate::a::b::c::d::e::f::F;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
-  --> $DIR/absolute_symbol_paths.rs:44:5
+  --> $DIR/absolute_symbol_paths.rs:45:5
    |
 LL |     crate::a::A;
    |     ^^^^^^^^^^^
 
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
-  --> $DIR/absolute_symbol_paths.rs:45:5
+  --> $DIR/absolute_symbol_paths.rs:46:5
    |
 LL |     crate::a::b::B;
    |     ^^^^^^^^^^^^^^
 
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
-  --> $DIR/absolute_symbol_paths.rs:46:5
+  --> $DIR/absolute_symbol_paths.rs:47:5
    |
 LL |     crate::a::b::c::C::ZERO;
    |     ^^^^^^^^^^^^^^^^^
 
 error: consider referring to this symbol by adding a `use` statement for consistent formatting
-  --> $DIR/absolute_symbol_paths.rs:47:5
+  --> $DIR/absolute_symbol_paths.rs:48:5
    |
 LL |     helper::b::c::d::e::f();
    |     ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 8 previous errors
+error: consider referring to this symbol by adding a `use` statement for consistent formatting
+  --> $DIR/absolute_symbol_paths.rs:49:5
+   |
+LL |     ::helper::b::c::d::e::f();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: consider referring to this symbol by adding a `use` statement for consistent formatting
+  --> $DIR/absolute_symbol_paths.rs:58:5
+   |
+LL |     ::std::f32::MAX;
+   |     ^^^^^^^^^^^^^^^
+
+error: aborting due to 11 previous errors
 

tests/ui-toml/absolute_symbol_paths/absolute_symbol_paths.rs

@@ -39,18 +39,25 @@ 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;