From cc622608db7318b1c0fe3ccd541558436c7c6c4c Mon Sep 17 00:00:00 2001
From: Andre Bogus <bogusandre@gmail.com>
Date: Wed, 18 Sep 2019 08:37:41 +0200
Subject: new lints around `#[must_use]` fns

`must_use_unit` lints unit-returning functions with a `#[must_use]`
attribute, suggesting to remove it.

`double_must_use` lints functions with a plain `#[must_use]`
attribute, but which return a type which is already `#[must_use]`,
so the attribute has no benefit.

`must_use_candidate` is a pedantic lint that lints functions and
methods that return some non-unit type that is not already
`#[must_use]` and suggests to add the annotation.
---
 clippy_dev/src/lib.rs                 | 7 +++++++
 clippy_dev/src/stderr_length_check.rs | 1 +
 2 files changed, 8 insertions(+)

(limited to 'clippy_dev')

diff --git a/clippy_dev/src/lib.rs b/clippy_dev/src/lib.rs
index 7df7109c75f..84b2814a7ce 100644
--- a/clippy_dev/src/lib.rs
+++ b/clippy_dev/src/lib.rs
@@ -42,6 +42,7 @@ pub struct Lint {
 }
 
 impl Lint {
+    #[must_use]
     pub fn new(name: &str, group: &str, desc: &str, deprecation: Option<&str>, module: &str) -> Self {
         Self {
             name: name.to_lowercase(),
@@ -58,6 +59,7 @@ impl Lint {
     }
 
     /// Returns the lints in a `HashMap`, grouped by the different lint groups
+    #[must_use]
     pub fn by_lint_group(lints: &[Self]) -> HashMap<String, Vec<Self>> {
         lints
             .iter()
@@ -65,12 +67,14 @@ impl Lint {
             .into_group_map()
     }
 
+    #[must_use]
     pub fn is_internal(&self) -> bool {
         self.group.starts_with("internal")
     }
 }
 
 /// Generates the Vec items for `register_lint_group` calls in `clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_lint_group_list(lints: Vec<Lint>) -> Vec<String> {
     lints
         .into_iter()
@@ -86,6 +90,7 @@ pub fn gen_lint_group_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the `pub mod module_name` list in `clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_modules_list(lints: Vec<Lint>) -> Vec<String> {
     lints
         .into_iter()
@@ -103,6 +108,7 @@ pub fn gen_modules_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the list of lint links at the bottom of the README
+#[must_use]
 pub fn gen_changelog_lint_list(lints: Vec<Lint>) -> Vec<String> {
     let mut lint_list_sorted: Vec<Lint> = lints;
     lint_list_sorted.sort_by_key(|l| l.name.clone());
@@ -119,6 +125,7 @@ pub fn gen_changelog_lint_list(lints: Vec<Lint>) -> Vec<String> {
 }
 
 /// Generates the `register_removed` code in `./clippy_lints/src/lib.rs`.
+#[must_use]
 pub fn gen_deprecated(lints: &[Lint]) -> Vec<String> {
     lints
         .iter()
diff --git a/clippy_dev/src/stderr_length_check.rs b/clippy_dev/src/stderr_length_check.rs
index 3049c45ddc8..2d7d119f3ff 100644
--- a/clippy_dev/src/stderr_length_check.rs
+++ b/clippy_dev/src/stderr_length_check.rs
@@ -42,6 +42,7 @@ fn stderr_files() -> impl Iterator<Item = walkdir::DirEntry> {
         .filter(|f| f.path().extension() == Some(OsStr::new("stderr")))
 }
 
+#[must_use]
 fn count_linenumbers(filepath: &str) -> usize {
     if let Ok(mut file) = File::open(filepath) {
         let mut content = String::new();
-- 
cgit 1.4.1-3-g733a5