tests: add regression test to make sure cfg_attr isn't considered unhandled

tests/ui/attributes/check-cfg_attr-ice.rs

@@ -0,0 +1,68 @@
+//! I missed a `cfg_attr` match in #128581, it should have had the same treatment as `cfg`. If
+//! an invalid attribute starting with `cfg_attr` is passed, then it would trigger an ICE because
+//! it was not considered "checked" (e.g. `#[cfg_attr::skip]` or `#[cfg_attr::no_such_thing]`).
+//!
+//! This test is not exhaustive, there's too many possible positions to check, instead it just does
+//! a basic smoke test in a few select positions to make sure we don't ICE for e.g.
+//! `#[cfg_attr::no_such_thing]`.
+//!
+//! issue: rust-lang/rust#128716
+#![crate_type = "lib"]
+
+#[cfg_attr::no_such_thing]
+//~^ ERROR failed to resolve
+mod we_are_no_strangers_to_love {}
+
+#[cfg_attr::no_such_thing]
+//~^ ERROR failed to resolve
+struct YouKnowTheRules {
+    #[cfg_attr::no_such_thing]
+    //~^ ERROR failed to resolve
+    and_so_do_i: u8,
+}
+
+#[cfg_attr::no_such_thing]
+//~^ ERROR failed to resolve
+fn a_full_commitment() {
+    #[cfg_attr::no_such_thing]
+    //~^ ERROR failed to resolve
+    let is_what_i_am_thinking_of = ();
+}
+
+#[cfg_attr::no_such_thing]
+//~^ ERROR failed to resolve
+union AnyOtherGuy {
+    owo: ()
+}
+struct This;
+
+#[cfg_attr(FALSE, doc = "you wouldn't get this")]
+impl From<AnyOtherGuy> for This {
+    #[cfg_attr::no_such_thing]
+    //~^ ERROR failed to resolve
+    fn from(#[cfg_attr::no_such_thing] any_other_guy: AnyOtherGuy) -> This {
+        //~^ ERROR failed to resolve
+        #[cfg_attr::no_such_thing]
+        //~^ ERROR attributes on expressions are experimental
+        //~| ERROR failed to resolve
+        unreachable!()
+    }
+}
+
+#[cfg_attr::no_such_thing]
+//~^ ERROR failed to resolve
+enum NeverGonna {
+    #[cfg_attr::no_such_thing]
+    //~^ ERROR failed to resolve
+    GiveYouUp(#[cfg_attr::no_such_thing] u8),
+    //~^ ERROR failed to resolve
+    LetYouDown {
+        #![cfg_attr::no_such_thing]
+        //~^ ERROR an inner attribute is not permitted in this context
+        never_gonna: (),
+        round_around: (),
+        #[cfg_attr::no_such_thing]
+        //~^ ERROR failed to resolve
+        and_desert_you: (),
+    },
+}

tests/ui/attributes/check-cfg_attr-ice.stderr

@@ -0,0 +1,101 @@
+error: an inner attribute is not permitted in this context
+  --> $DIR/check-cfg_attr-ice.rs:60:9
+   |
+LL |         #![cfg_attr::no_such_thing]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files
+   = note: outer attributes, like `#[test]`, annotate the item following them
+
+error[E0658]: attributes on expressions are experimental
+  --> $DIR/check-cfg_attr-ice.rs:45:9
+   |
+LL |         #[cfg_attr::no_such_thing]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
+   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:52:3
+   |
+LL | #[cfg_attr::no_such_thing]
+   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:55:7
+   |
+LL |     #[cfg_attr::no_such_thing]
+   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:57:17
+   |
+LL |     GiveYouUp(#[cfg_attr::no_such_thing] u8),
+   |                 ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:64:11
+   |
+LL |         #[cfg_attr::no_such_thing]
+   |           ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:41:7
+   |
+LL |     #[cfg_attr::no_such_thing]
+   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:43:15
+   |
+LL |     fn from(#[cfg_attr::no_such_thing] any_other_guy: AnyOtherGuy) -> This {
+   |               ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:45:11
+   |
+LL |         #[cfg_attr::no_such_thing]
+   |           ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:32:3
+   |
+LL | #[cfg_attr::no_such_thing]
+   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:24:3
+   |
+LL | #[cfg_attr::no_such_thing]
+   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:27:7
+   |
+LL |     #[cfg_attr::no_such_thing]
+   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:16:3
+   |
+LL | #[cfg_attr::no_such_thing]
+   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:19:7
+   |
+LL |     #[cfg_attr::no_such_thing]
+   |       ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error[E0433]: failed to resolve: use of undeclared crate or module `cfg_attr`
+  --> $DIR/check-cfg_attr-ice.rs:12:3
+   |
+LL | #[cfg_attr::no_such_thing]
+   |   ^^^^^^^^ use of undeclared crate or module `cfg_attr`
+
+error: aborting due to 15 previous errors
+
+Some errors have detailed explanations: E0433, E0658.
+For more information about an error, try `rustc --explain E0433`.