Add cfg_attr lint

CHANGELOG.md

@@ -651,6 +651,7 @@ All notable changes to this project will be documented in this file.
 [`decimal_literal_representation`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#decimal_literal_representation
 [`declare_interior_mutable_const`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#declare_interior_mutable_const
 [`default_trait_access`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#default_trait_access
+[`deprecated_cfg_attr`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#deprecated_cfg_attr
 [`deprecated_semver`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#deprecated_semver
 [`deref_addrof`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#deref_addrof
 [`derive_hash_xor_eq`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#derive_hash_xor_eq

README.md

@@ -9,7 +9,7 @@ We are currently in the process of discussing Clippy 1.0 via the RFC process in
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 283 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
+[There are 284 lints included in this crate!](https://rust-lang-nursery.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/attrs.rs

@@ -13,10 +13,10 @@
 use crate::reexport::*;
 use crate::utils::{
     in_macro, last_line_of_span, match_def_path, opt_def_id, paths, snippet_opt, span_lint, span_lint_and_then,
-    without_block_comments,
+    span_lint_and_sugg, without_block_comments,
 };
 use crate::rustc::hir::*;
-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use crate::rustc::lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintArray, LintPass};
 use crate::rustc::{declare_tool_lint, lint_array};
 use if_chain::if_chain;
 use crate::rustc::ty::{self, TyCtxt};
@@ -138,6 +138,19 @@ declare_clippy_lint! {
     "empty line after outer attribute"
 }
 
+/// **What it does:**
+///
+/// **Why is this bad?**
+///
+/// **Known problems:**
+///
+/// **Example:**
+declare_clippy_lint! {
+    pub DEPRECATED_CFG_ATTR,
+    complexity,
+    "usage of `cfg_attr` instead of `tool_lints`"
+}
+
 #[derive(Copy, Clone)]
 pub struct AttrPass;
 
@@ -387,3 +400,63 @@ fn is_present_in_source(cx: &LateContext<'_, '_>, span: Span) -> bool {
     }
     true
 }
+
+#[derive(Copy, Clone)]
+pub struct CfgAttrPass;
+
+impl LintPass for CfgAttrPass {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(
+            DEPRECATED_CFG_ATTR,
+        )
+    }
+}
+
+impl EarlyLintPass for CfgAttrPass {
+    fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &Attribute) {
+        if_chain! {
+            // check cfg_attr
+            if attr.name() == "cfg_attr";
+            if let Some(ref items) = attr.meta_item_list();
+            if items.len() == 2;
+            // check for `feature = "cargo-clippy"`
+            if let Some(feature_item) = items[0].meta_item();
+            if let Some(value) = feature_item.value_str();
+            if value == "cargo-clippy";
+            // check for `allow(..)`/... and retrieve the lints
+            let level = &items[1];
+            if let Some(name) = level.name();
+            if name == "allow" || name == "warn" || name == "deny" || name == "forbid";
+            if let Some(level_items) = level.meta_item_list();
+            if level_items.iter().all(|item| {
+                if let Some(meta_item) = item.meta_item() {
+                    meta_item.is_word()
+                } else {
+                    false
+                }
+            });
+            then {
+                let attr_style = match attr.style {
+                    AttrStyle::Outer => "#[",
+                    AttrStyle::Inner => "#![",
+                };
+                let level = name.as_str();
+                let mut lints = level_items.iter().fold(String::new(), |acc, item| {
+                    acc + &format!("clippy::{}, ", item.name().unwrap().as_str())
+                });
+                let lints_len = lints.len();
+                lints.truncate(lints_len - 2);
+                let sugg = format!("{}{}({})]", attr_style, level, lints);
+                span_lint_and_sugg(
+                    cx,
+                    DEPRECATED_CFG_ATTR,
+                    attr.span,
+                    "`cfg_attr` is deprecated for clippy and got replaced by tool_lints",
+                    "use",
+                    sugg,
+                );
+            }
+        }
+    }
+}
+

clippy_lints/src/lib.rs

@@ -220,6 +220,7 @@ pub fn register_pre_expansion_lints(session: &rustc::session::Session, store: &m
     store.register_pre_expansion_pass(Some(session), box non_expressive_names::NonExpressiveNames {
         single_char_binding_names_threshold: conf.single_char_binding_names_threshold,
     });
+    store.register_pre_expansion_pass(Some(session), box attrs::CfgAttrPass);
 }
 
 pub fn read_conf(reg: &rustc_plugin::Registry<'_>) -> Conf {
@@ -531,6 +532,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
         approx_const::APPROX_CONSTANT,
         assign_ops::ASSIGN_OP_PATTERN,
         assign_ops::MISREFACTORED_ASSIGN_OP,
+        attrs::DEPRECATED_CFG_ATTR,
         attrs::DEPRECATED_SEMVER,
         attrs::USELESS_ATTRIBUTE,
         bit_mask::BAD_BIT_MASK,
@@ -833,6 +835,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
 
     reg.register_lint_group("clippy::complexity", Some("clippy_complexity"), vec![
         assign_ops::MISREFACTORED_ASSIGN_OP,
+        attrs::DEPRECATED_CFG_ATTR,
         booleans::NONMINIMAL_BOOL,
         cyclomatic_complexity::CYCLOMATIC_COMPLEXITY,
         double_comparison::DOUBLE_COMPARISONS,