Auto merge of rust-lang#7120 - cherryblossom000:7106, r=Manishearth

`single_component_path_imports`: ignore `pub(crate) use some_macro;`

Fixes rust-lang#7106

*Please write a short comment explaining your change (or "none" for internal only changes)*

changelog: Ignore exporting a macro within a crate using `pub(crate) use some_macro;` for [`single_component_path_imports`]

Author: bors

clippy_lints/src/single_component_path_imports.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
 use clippy_utils::in_macro;
-use rustc_ast::{ptr::P, Crate, Item, ItemKind, ModKind, UseTreeKind};
+use rustc_ast::{ptr::P, Crate, Item, ItemKind, MacroDef, ModKind, UseTreeKind, VisibilityKind};
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -60,8 +60,21 @@ fn check_mod(cx: &EarlyContext<'_>, items: &[P<Item>]) {
     // ```
     let mut single_use_usages = Vec::new();
 
+    // keep track of macros defined in the module as we don't want it to trigger on this (#7106)
+    // ```rust,ignore
+    // macro_rules! foo { () => {} };
+    // pub(crate) use foo;
+    // ```
+    let mut macros = Vec::new();
+
     for item in items {
-        track_uses(cx, &item, &mut imports_reused_with_self, &mut single_use_usages);
+        track_uses(
+            cx,
+            &item,
+            &mut imports_reused_with_self,
+            &mut single_use_usages,
+            &mut macros,
+        );
     }
 
     for single_use in &single_use_usages {
@@ -96,6 +109,7 @@ fn track_uses(
     item: &Item,
     imports_reused_with_self: &mut Vec<Symbol>,
     single_use_usages: &mut Vec<(Symbol, Span, bool)>,
+    macros: &mut Vec<Symbol>,
 ) {
     if in_macro(item.span) || item.vis.kind.is_pub() {
         return;
@@ -105,14 +119,22 @@ fn track_uses(
         ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) => {
             check_mod(cx, &items);
         },
+        ItemKind::MacroDef(MacroDef { macro_rules: true, .. }) => {
+            macros.push(item.ident.name);
+        },
         ItemKind::Use(use_tree) => {
             let segments = &use_tree.prefix.segments;
 
+            let should_report =
+                |name: &Symbol| !macros.contains(name) || matches!(item.vis.kind, VisibilityKind::Inherited);
+
             // keep track of `use some_module;` usages
             if segments.len() == 1 {
                 if let UseTreeKind::Simple(None, _, _) = use_tree.kind {
-                    let ident = &segments[0].ident;
-                    single_use_usages.push((ident.name, item.span, true));
+                    let name = segments[0].ident.name;
+                    if should_report(&name) {
+                        single_use_usages.push((name, item.span, true));
+                    }
                 }
                 return;
             }
@@ -124,8 +146,10 @@ fn track_uses(
                         let segments = &tree.0.prefix.segments;
                         if segments.len() == 1 {
                             if let UseTreeKind::Simple(None, _, _) = tree.0.kind {
-                                let ident = &segments[0].ident;
-                                single_use_usages.push((ident.name, tree.0.span, false));
+                                let name = segments[0].ident.name;
+                                if should_report(&name) {
+                                    single_use_usages.push((name, tree.0.span, false));
+                                }
                             }
                         }
                     }

tests/ui/single_component_path_imports_macro.fixed

@@ -0,0 +1,21 @@
+// run-rustfix
+// edition:2018
+#![warn(clippy::single_component_path_imports)]
+#![allow(unused_imports)]
+
+// #7106: use statements exporting a macro within a crate should not trigger lint
+
+macro_rules! m1 {
+    () => {};
+}
+pub(crate) use m1; // ok
+
+macro_rules! m2 {
+    () => {};
+}
+ // fail
+
+fn main() {
+    m1!();
+    m2!();
+}

tests/ui/single_component_path_imports_macro.rs

@@ -0,0 +1,21 @@
+// run-rustfix
+// edition:2018
+#![warn(clippy::single_component_path_imports)]
+#![allow(unused_imports)]
+
+// #7106: use statements exporting a macro within a crate should not trigger lint
+
+macro_rules! m1 {
+    () => {};
+}
+pub(crate) use m1; // ok
+
+macro_rules! m2 {
+    () => {};
+}
+use m2; // fail
+
+fn main() {
+    m1!();
+    m2!();
+}

tests/ui/single_component_path_imports_macro.stderr

@@ -0,0 +1,10 @@
+error: this import is redundant
+  --> $DIR/single_component_path_imports_macro.rs:16:1
+   |
+LL | use m2; // fail
+   | ^^^^^^^ help: remove it entirely
+   |
+   = note: `-D clippy::single-component-path-imports` implied by `-D warnings`
+
+error: aborting due to previous error
+