Add new lint: `map_all_any_identity`

3 files changed, 68 insertions, 0 deletions

diff --git a/tests/ui/map_all_any_identity.fixed b/tests/ui/map_all_any_identity.fixed
new file mode 100644
index 00000000000..c92462ab9c2
--- /dev/null
+++ b/tests/ui/map_all_any_identity.fixed
@@ -0,0 +1,21 @@
+#![warn(clippy::map_all_any_identity)]
+
+fn main() {
+    let _ = ["foo"].into_iter().any(|s| s == "foo");
+    //~^ map_all_any_identity
+    let _ = ["foo"].into_iter().all(|s| s == "foo");
+    //~^ map_all_any_identity
+
+    //
+    // Do not lint
+    //
+    // Not identity
+    let _ = ["foo"].into_iter().map(|s| s.len()).any(|n| n > 0);
+    // Macro
+    macro_rules! map {
+        ($x:expr) => {
+            $x.into_iter().map(|s| s == "foo")
+        };
+    }
+    map!(["foo"]).any(|a| a);
+}
diff --git a/tests/ui/map_all_any_identity.rs b/tests/ui/map_all_any_identity.rs
new file mode 100644
index 00000000000..0e4a564ca04
--- /dev/null
+++ b/tests/ui/map_all_any_identity.rs
@@ -0,0 +1,21 @@
+#![warn(clippy::map_all_any_identity)]
+
+fn main() {
+    let _ = ["foo"].into_iter().map(|s| s == "foo").any(|a| a);
+    //~^ map_all_any_identity
+    let _ = ["foo"].into_iter().map(|s| s == "foo").all(std::convert::identity);
+    //~^ map_all_any_identity
+
+    //
+    // Do not lint
+    //
+    // Not identity
+    let _ = ["foo"].into_iter().map(|s| s.len()).any(|n| n > 0);
+    // Macro
+    macro_rules! map {
+        ($x:expr) => {
+            $x.into_iter().map(|s| s == "foo")
+        };
+    }
+    map!(["foo"]).any(|a| a);
+}
diff --git a/tests/ui/map_all_any_identity.stderr b/tests/ui/map_all_any_identity.stderr
new file mode 100644
index 00000000000..98fdcc2a939
--- /dev/null
+++ b/tests/ui/map_all_any_identity.stderr
@@ -0,0 +1,26 @@
+error: usage of `.map(...).any(identity)`
+  --> tests/ui/map_all_any_identity.rs:4:33
+   |
+LL |     let _ = ["foo"].into_iter().map(|s| s == "foo").any(|a| a);
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::map-all-any-identity` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::map_all_any_identity)]`
+help: use `.any(...)` instead
+   |
+LL |     let _ = ["foo"].into_iter().any(|s| s == "foo");
+   |                                 ~~~~~~~~~~~~~~~~~~~
+
+error: usage of `.map(...).all(identity)`
+  --> tests/ui/map_all_any_identity.rs:6:33
+   |
+LL |     let _ = ["foo"].into_iter().map(|s| s == "foo").all(std::convert::identity);
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: use `.all(...)` instead
+   |
+LL |     let _ = ["foo"].into_iter().all(|s| s == "foo");
+   |                                 ~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 2 previous errors
+