New lint: Unknown clippy lints

CHANGELOG.md

@@ -866,6 +866,7 @@ All notable changes to this project will be documented in this file.
 [`unimplemented`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unimplemented
 [`unit_arg`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unit_arg
 [`unit_cmp`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unit_cmp
+[`unknown_clippy_lints`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unknown_clippy_lints
 [`unnecessary_cast`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unnecessary_cast
 [`unnecessary_filter_map`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unnecessary_filter_map
 [`unnecessary_fold`]: https://rust-lang-nursery.github.io/rust-clippy/master/index.html#unnecessary_fold

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

@@ -12,16 +12,20 @@
 
 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,
+    in_macro, last_line_of_span, match_def_path, opt_def_id, paths, snippet_opt, span_lint,
+    span_lint_and_then, without_block_comments,
 };
-use crate::rustc::hir::*;
-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use crate::rustc::{declare_tool_lint, lint_array};
 use if_chain::if_chain;
+use crate::rustc::hir::*;
+use crate::rustc::lint::{
+    CheckLintNameResult, LateContext, LateLintPass, LintArray, LintContext, LintPass,
+};
 use crate::rustc::ty::{self, TyCtxt};
+use crate::rustc::{declare_tool_lint, lint_array};
 use semver::Version;
-use crate::syntax::ast::{AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
+use crate::syntax::ast::{
+    AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem, NestedMetaItemKind,
+};
 use crate::syntax::source_map::Span;
 use crate::rustc_errors::Applicability;
 
@@ -138,6 +142,33 @@ declare_clippy_lint! {
     "empty line after outer attribute"
 }
 
+/// **What it does:** Checks for `allow`/`warn`/`deny`/`forbid` attributes with scoped clippy
+/// lints and if those lints exist in clippy. If there is a uppercase letter in the lint name
+/// (not the tool name) and a lowercase version of this lint exists, it will suggest to lowercase
+/// the lint name.
+///
+/// **Why is this bad?** A lint attribute with a mistyped lint name won't have an effect.
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// Bad:
+/// ```rust
+/// #![warn(if_not_els)]
+/// #![deny(clippy::All)]
+/// ```
+///
+/// Good:
+/// ```rust
+/// #![warn(if_not_else)]
+/// #![deny(clippy::all)]
+/// ```
+declare_clippy_lint! {
+    pub UNKNOWN_CLIPPY_LINTS,
+    style,
+    "unknown_lints for scoped Clippy lints"
+}
+
 #[derive(Copy, Clone)]
 pub struct AttrPass;
 
@@ -147,14 +178,21 @@ impl LintPass for AttrPass {
             INLINE_ALWAYS,
             DEPRECATED_SEMVER,
             USELESS_ATTRIBUTE,
-            EMPTY_LINE_AFTER_OUTER_ATTR
+            EMPTY_LINE_AFTER_OUTER_ATTR,
+            UNKNOWN_CLIPPY_LINTS,
         )
     }
 }
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AttrPass {
     fn check_attribute(&mut self, cx: &LateContext<'a, 'tcx>, attr: &'tcx Attribute) {
         if let Some(ref items) = attr.meta_item_list() {
+            match &*attr.name().as_str() {
+                "allow" | "warn" | "deny" | "forbid" => {
+                    check_clippy_lint_names(cx, items);
+                }
+                _ => {}
+            }
             if items.is_empty() || attr.name() != "deprecated" {
                 return;
             }
@@ -247,6 +285,47 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AttrPass {
     }
 }
 
+#[allow(clippy::single_match_else)]
+fn check_clippy_lint_names(cx: &LateContext<'_, '_>, items: &[NestedMetaItem]) {
+    let lint_store = cx.lints();
+    for lint in items {
+        if_chain! {
+            if let Some(word) = lint.word();
+            if let Some(tool_name) = word.is_scoped();
+            if tool_name.as_str() == "clippy";
+            let name = word.name();
+            if let CheckLintNameResult::Tool(Err((None, _))) = lint_store.check_lint_name(
+                &name.as_str(),
+                Some(tool_name.as_str()),
+            );
+            then {
+                span_lint_and_then(
+                    cx,
+                    UNKNOWN_CLIPPY_LINTS,
+                    lint.span,
+                    &format!("unknown clippy lint: clippy::{}", name),
+                    |db| {
+                        if name.as_str().chars().any(|c| c.is_uppercase()) {
+                            let name_lower = name.as_str().to_lowercase().to_string();
+                            match lint_store.check_lint_name(
+                                &name_lower,
+                                Some(tool_name.as_str())
+                            ) {
+                                CheckLintNameResult::NoLint => (),
+                                _ => {
+                                    db.span_suggestion(lint.span,
+                                                       "lowercase the lint name",
+                                                       name_lower);
+                                }
+                            }
+                        }
+                    }
+                );
+            }
+        };
+    }
+}
+
 fn is_relevant_item(tcx: TyCtxt<'_, '_, '_>, item: &Item) -> bool {
     if let ItemKind::Fn(_, _, _, eid) = item.node {
         is_relevant_expr(tcx, tcx.body_tables(eid), &tcx.hir.body(eid).value)

clippy_lints/src/lib.rs

@@ -533,6 +533,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
         assign_ops::ASSIGN_OP_PATTERN,
         assign_ops::MISREFACTORED_ASSIGN_OP,
         attrs::DEPRECATED_SEMVER,
+        attrs::UNKNOWN_CLIPPY_LINTS,
         attrs::USELESS_ATTRIBUTE,
         bit_mask::BAD_BIT_MASK,
         bit_mask::INEFFECTIVE_BIT_MASK,
@@ -749,6 +750,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>, conf: &Conf) {
 
     reg.register_lint_group("clippy::style", Some("clippy_style"), vec![
         assign_ops::ASSIGN_OP_PATTERN,
+        attrs::UNKNOWN_CLIPPY_LINTS,
         bit_mask::VERBOSE_BIT_MASK,
         blacklisted_name::BLACKLISTED_NAME,
         block_in_if_condition::BLOCK_IN_IF_CONDITION_EXPR,

tests/ui/unknown_clippy_lints.rs

@@ -0,0 +1,16 @@
+// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![allow(clippy::All)]
+#![warn(clippy::pedantic)]
+
+#[warn(clippy::if_not_els)]
+fn main() {
+
+}

tests/ui/unknown_clippy_lints.stderr

@@ -0,0 +1,16 @@
+error: unknown clippy lint: clippy::if_not_els
+  --> $DIR/unknown_clippy_lints.rs:13:8
+   |
+13 | #[warn(clippy::if_not_els)]
+   |        ^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::unknown-clippy-lints` implied by `-D warnings`
+
+error: unknown clippy lint: clippy::All
+  --> $DIR/unknown_clippy_lints.rs:10:10
+   |
+10 | #![allow(clippy::All)]
+   |          ^^^^^^^^^^^ help: lowercase the lint name: `all`
+
+error: aborting due to 2 previous errors
+