From dbc76a766333bf510de601111f31e3eb42fb0434 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 19 May 2023 16:23:17 +0200
Subject: [PATCH] Add check for empty cfg `all` condition

---
 clippy_lints/src/attrs.rs        |  8 ++++++++
 tests/ui/non_minimal_cfg.fixed   |  3 +++
 tests/ui/non_minimal_cfg.rs      |  3 +++
 tests/ui/non_minimal_cfg2.rs     |  6 ++++++
 tests/ui/non_minimal_cfg2.stderr | 10 ++++++++++
 5 files changed, 30 insertions(+)
 create mode 100644 tests/ui/non_minimal_cfg2.rs
 create mode 100644 tests/ui/non_minimal_cfg2.stderr

diff --git a/clippy_lints/src/attrs.rs b/clippy_lints/src/attrs.rs
index 6678002820a..897495ba108 100644
--- a/clippy_lints/src/attrs.rs
+++ b/clippy_lints/src/attrs.rs
@@ -796,6 +796,14 @@ fn check_nested_cfg(cx: &EarlyContext<'_>, items: &[NestedMetaItem]) {
                             }
                         },
                     );
+                } else if list.is_empty() && meta.has_name(sym::all) {
+                    span_lint_and_then(
+                        cx,
+                        NON_MINIMAL_CFG,
+                        meta.span,
+                        "unneeded sub `cfg` when there is no condition",
+                        |_| {},
+                    );
                 }
             }
         }
diff --git a/tests/ui/non_minimal_cfg.fixed b/tests/ui/non_minimal_cfg.fixed
index ca9a48a3e37..430caafb33e 100644
--- a/tests/ui/non_minimal_cfg.fixed
+++ b/tests/ui/non_minimal_cfg.fixed
@@ -11,4 +11,7 @@ fn wasi() {}
 #[cfg(all(unix, not(windows)))]
 fn the_end() {}
 
+#[cfg(any())]
+fn any() {}
+
 fn main() {}
diff --git a/tests/ui/non_minimal_cfg.rs b/tests/ui/non_minimal_cfg.rs
index bf322236fef..a38ce1c21d6 100644
--- a/tests/ui/non_minimal_cfg.rs
+++ b/tests/ui/non_minimal_cfg.rs
@@ -11,4 +11,7 @@ fn wasi() {}
 #[cfg(all(any(unix), all(not(windows))))]
 fn the_end() {}
 
+#[cfg(any())]
+fn any() {}
+
 fn main() {}
diff --git a/tests/ui/non_minimal_cfg2.rs b/tests/ui/non_minimal_cfg2.rs
new file mode 100644
index 00000000000..a4c6abce387
--- /dev/null
+++ b/tests/ui/non_minimal_cfg2.rs
@@ -0,0 +1,6 @@
+#![allow(unused)]
+
+#[cfg(all())]
+fn all() {}
+
+fn main() {}
diff --git a/tests/ui/non_minimal_cfg2.stderr b/tests/ui/non_minimal_cfg2.stderr
new file mode 100644
index 00000000000..2a9a36fbcef
--- /dev/null
+++ b/tests/ui/non_minimal_cfg2.stderr
@@ -0,0 +1,10 @@
+error: unneeded sub `cfg` when there is no condition
+  --> $DIR/non_minimal_cfg2.rs:3:7
+   |
+LL | #[cfg(all())]
+   |       ^^^^^
+   |
+   = note: `-D clippy::non-minimal-cfg` implied by `-D warnings`
+
+error: aborting due to previous error
+