Add regression test for codegen attributes on required trait methods

Signed-off-by: Jonathan Brouwer <[email protected]>

Author: JonathanBrouwer

tests/ui/attributes/codegen_attr_on_required_trait_method.rs

@@ -0,0 +1,24 @@
+#![deny(unused_attributes)]
+#![feature(linkage)]
+#![feature(fn_align)]
+
+trait Test {
+    #[cold]
+    //~^ ERROR cannot be used on required trait methods [unused_attributes]
+    //~| WARN previously accepted
+    fn method1(&self);
+    #[link_section = ".text"]
+    //~^ ERROR cannot be used on required trait methods [unused_attributes]
+    //~| WARN previously accepted
+    fn method2(&self);
+    #[linkage = "common"]
+    //~^ ERROR cannot be used on required trait methods [unused_attributes]
+    //~| WARN previously accepted
+    fn method3(&self);
+    #[track_caller]
+    fn method4(&self);
+    #[rustc_align(1)]
+    fn method5(&self);
+}
+
+fn main() {}

tests/ui/attributes/codegen_attr_on_required_trait_method.stderr

@@ -0,0 +1,34 @@
+error: `#[cold]` attribute cannot be used on required trait methods
+  --> $DIR/codegen_attr_on_required_trait_method.rs:6:5
+   |
+LL |     #[cold]
+   |     ^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[cold]` can be applied to closures, foreign functions, functions, inherent methods, provided trait methods, and trait methods in impl blocks
+note: the lint level is defined here
+  --> $DIR/codegen_attr_on_required_trait_method.rs:1:9
+   |
+LL | #![deny(unused_attributes)]
+   |         ^^^^^^^^^^^^^^^^^
+
+error: `#[link_section]` attribute cannot be used on required trait methods
+  --> $DIR/codegen_attr_on_required_trait_method.rs:10:5
+   |
+LL |     #[link_section = ".text"]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[link_section]` can be applied to functions, inherent methods, provided trait methods, statics, and trait methods in impl blocks
+
+error: `#[linkage]` attribute cannot be used on required trait methods
+  --> $DIR/codegen_attr_on_required_trait_method.rs:14:5
+   |
+LL |     #[linkage = "common"]
+   |     ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[linkage]` can be applied to foreign functions, foreign statics, functions, inherent methods, provided trait methods, statics, and trait methods in impl blocks
+
+error: aborting due to 3 previous errors
+