Error on invalid uses of the cfi_encoding attribute.

Author: mejrs

compiler/rustc_attr_parsing/src/attributes/cfi_encoding.rs

@@ -4,7 +4,7 @@ use super::prelude::*;
 pub(crate) struct CfiEncodingParser;
 impl SingleAttributeParser for CfiEncodingParser {
     const PATH: &[Symbol] = &[sym::cfi_encoding];
-    const ALLOWED_TARGETS: AllowedTargets<'_> = AllowedTargets::AllowListWarnRest(&[
+    const ALLOWED_TARGETS: AllowedTargets<'_> = AllowedTargets::AllowList(&[
         Allow(Target::Struct),
         Allow(Target::ForeignTy),
         Allow(Target::Enum),

tests/ui/sanitizer/cfi/invalid-attr-encoding.rs

@@ -1,11 +1,13 @@
-// Verifies that invalid user-defined CFI encodings can't be used.
-//
-//@ needs-sanitizer-cfi
-//@ compile-flags: -Clto -Cno-prepopulate-passes -Ctarget-feature=-crt-static -Zsanitizer=cfi
+//! Checks for invalid uses of the `cfi_encoding` attribute
 
-#![feature(cfi_encoding, no_core)]
-#![no_core]
-#![no_main]
+#![feature(cfi_encoding)]
+#![crate_type = "lib"]
 
 #[cfi_encoding] //~ ERROR malformed `cfi_encoding` attribute input
 pub struct Type1(i32);
+
+#[cfi_encoding = "Foo"] //~ ERROR  the `cfi_encoding` attribute cannot be used on traits
+pub trait X {}
+
+#[cfi_encoding = "Bar"] //~ ERROR  the `cfi_encoding` attribute cannot be used on type aliases
+pub type Y = Type1;

tests/ui/sanitizer/cfi/invalid-attr-encoding.stderr

@@ -1,5 +1,5 @@
 error[E0539]: malformed `cfi_encoding` attribute input
-  --> $DIR/invalid-attr-encoding.rs:10:3
+  --> $DIR/invalid-attr-encoding.rs:7:3
    |
 LL | #[cfi_encoding]
    |   ^^^^^^^^^^^^ expected this to be of the form `cfi_encoding = "..."`
@@ -9,6 +9,22 @@ help: must be of the form
 LL | #[cfi_encoding = "encoding"]
    |                ++++++++++++
 
-error: aborting due to 1 previous error
+error: the `cfi_encoding` attribute cannot be used on traits
+  --> $DIR/invalid-attr-encoding.rs:10:3
+   |
+LL | #[cfi_encoding = "Foo"]
+   |   ^^^^^^^^^^^^
+   |
+   = help: the `cfi_encoding` attribute can only be applied to data types
+
+error: the `cfi_encoding` attribute cannot be used on type aliases
+  --> $DIR/invalid-attr-encoding.rs:13:3
+   |
+LL | #[cfi_encoding = "Bar"]
+   |   ^^^^^^^^^^^^
+   |
+   = help: the `cfi_encoding` attribute can only be applied to data types
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0539`.