stop [mixed_attributes_style] from linting on different attributes

Author: J-ZhengLi

clippy_lints/src/attrs/mixed_attributes_style.rs

@@ -3,19 +3,29 @@ use clippy_utils::diagnostics::span_lint;
 use rustc_ast::{AttrKind, AttrStyle, Attribute};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_lint::{LateContext, LintContext};
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 use std::sync::Arc;
 
 #[derive(Hash, PartialEq, Eq)]
 enum SimpleAttrKind {
     Doc,
-    Normal,
+    /// A normal attribute, with its name symbols.
+    Normal(Vec<Symbol>),
 }
 
 impl From<&AttrKind> for SimpleAttrKind {
     fn from(value: &AttrKind) -> Self {
         match value {
-            AttrKind::Normal(_) => Self::Normal,
+            AttrKind::Normal(attr) => {
+                let path_symbols = attr
+                    .item
+                    .path
+                    .segments
+                    .iter()
+                    .map(|seg| seg.ident.name)
+                    .collect::<Vec<_>>();
+                Self::Normal(path_symbols)
+            },
             AttrKind::DocComment(..) => Self::Doc,
         }
     }

clippy_lints/src/attrs/mod.rs

@@ -465,10 +465,20 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks that an item has only one kind of attributes.
+    /// Checks for item that has same kind of attributes with mixed styles (inner/outer).
     ///
     /// ### Why is this bad?
-    /// Having both kinds of attributes makes it more complicated to read code.
+    /// Having both style of said attributes makes it more complicated to read code.
+    ///
+    /// ### Known problems
+    /// This lint currently have false-nagative when mixing same attributes
+    /// but they have different path symbols, for example:
+    /// ```ignore
+    /// #[custom_attribute]
+    /// pub fn foo() {
+    ///     #![my_crate::custom_attribute]
+    /// }
+    /// ```
     ///
     /// ### Example
     /// ```no_run

tests/ui/mixed_attributes_style.rs

@@ -1,6 +1,10 @@
+//@aux-build:proc_macro_attr.rs
+#![feature(custom_inner_attributes)]
 #![warn(clippy::mixed_attributes_style)]
 #![allow(clippy::duplicated_attributes)]
 
+use proc_macro_attr::dummy;
+
 #[allow(unused)] //~ ERROR: item has both inner and outer attributes
 fn foo1() {
     #![allow(unused)]
@@ -53,3 +57,45 @@ mod baz {
 mod quz {
     #![allow(unused)]
 }
+
+// issue #12530, don't lint different attributes entirely
+#[cfg(test)]
+mod tests {
+    #![allow(clippy::unreadable_literal)]
+}
+#[cfg(unix)]
+mod another_mod {
+    #![allow(clippy::question_mark)]
+}
+/// Nested mod - Good
+mod nested_mod {
+    #[allow(dead_code)] //~ ERROR: item has both inner and outer attributes
+    mod inner_mod {
+        #![allow(dead_code)]
+    }
+}
+/// Nested mod - Good //~ ERROR: item has both inner and outer attributes
+#[allow(unused)]
+mod nest_mod_2 {
+    #![allow(unused)]
+
+    #[allow(dead_code)] //~ ERROR: item has both inner and outer attributes
+    mod inner_mod {
+        #![allow(dead_code)]
+    }
+}
+/// Nested mod - Possible FN
+#[cfg(test)]
+mod nested_mod_false_nagative {
+    #![allow(unused)]
+
+    #[allow(dead_code)] // This should lint but it does not, removing the `#[cfg(test)]` solves the problem.
+    mod inner_mod {
+        #![allow(dead_code)]
+    }
+}
+// Different path symbols - Known FN
+#[dummy]
+fn use_dummy() {
+    #![proc_macro_attr::dummy]
+}

tests/ui/mixed_attributes_style.stderr

@@ -1,5 +1,5 @@
 error: item has both inner and outer attributes
-  --> tests/ui/mixed_attributes_style.rs:4:1
+  --> tests/ui/mixed_attributes_style.rs:8:1
    |
 LL | / #[allow(unused)]
 LL | | fn foo1() {
@@ -10,7 +10,7 @@ LL | |     #![allow(unused)]
    = help: to override `-D warnings` add `#[allow(clippy::mixed_attributes_style)]`
 
 error: item has both inner and outer attributes
-  --> tests/ui/mixed_attributes_style.rs:18:1
+  --> tests/ui/mixed_attributes_style.rs:22:1
    |
 LL | / /// linux
 LL | |
@@ -19,12 +19,37 @@ LL | |     //! windows
    | |_______________^
 
 error: item has both inner and outer attributes
-  --> tests/ui/mixed_attributes_style.rs:33:1
+  --> tests/ui/mixed_attributes_style.rs:37:1
    |
 LL | / #[allow(unused)]
 LL | | mod bar {
 LL | |     #![allow(unused)]
    | |_____________________^
 
-error: aborting due to 3 previous errors
+error: item has both inner and outer attributes
+  --> tests/ui/mixed_attributes_style.rs:72:5
+   |
+LL | /     #[allow(dead_code)]
+LL | |     mod inner_mod {
+LL | |         #![allow(dead_code)]
+   | |____________________________^
+
+error: item has both inner and outer attributes
+  --> tests/ui/mixed_attributes_style.rs:77:1
+   |
+LL | / /// Nested mod - Good
+LL | | #[allow(unused)]
+LL | | mod nest_mod_2 {
+LL | |     #![allow(unused)]
+   | |_____________________^
+
+error: item has both inner and outer attributes
+  --> tests/ui/mixed_attributes_style.rs:82:5
+   |
+LL | /     #[allow(dead_code)]
+LL | |     mod inner_mod {
+LL | |         #![allow(dead_code)]
+   | |____________________________^
+
+error: aborting due to 6 previous errors