Rollup merge of rust-lang#61024 - petrochenkov:proctest, r=nikomatsakis

tests: Centralize proc macros commonly used for testing

Many proc macros in `ui\proc-macro\auxiliary` were doing same things.
(I added a fair share of those myself.)

Now commonly used macros (empty, identity, etc) are collected in one place - `ui\proc-macro\auxiliary\test-macros.rs`.

Author: Centril

src/test/ui/custom-derive/auxiliary/plugin.rs

@@ -1,14 +1,14 @@
-// aux-build:attr_proc_macro.rs
+// aux-build:test-macros.rs
 
-extern crate attr_proc_macro;
-use attr_proc_macro::*;
+#[macro_use]
+extern crate test_macros;
 
-#[attr_proc_macro] // OK
+#[identity_attr] // OK
 #[derive(Clone)]
 struct Before;
 
 #[derive(Clone)]
-#[attr_proc_macro] //~ ERROR macro attributes must be placed before `#[derive]`
+#[identity_attr] //~ ERROR macro attributes must be placed before `#[derive]`
 struct After;
 
 fn main() {}

src/test/ui/custom-derive/derive-in-mod.rs

@@ -1,8 +1,8 @@
 error: macro attributes must be placed before `#[derive]`
   --> $DIR/attribute-order-restricted.rs:11:1
    |
-LL | #[attr_proc_macro]
-   | ^^^^^^^^^^^^^^^^^^
+LL | #[identity_attr]
+   | ^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/custom-derive/helper-attr-blocked-by-import-ambig.rs

@@ -1,12 +1,11 @@
-// aux-build:attribute-with-error.rs
+// aux-build:test-macros.rs
 
 #![feature(custom_inner_attributes)]
 
-extern crate attribute_with_error;
+#[macro_use]
+extern crate test_macros;
 
-use attribute_with_error::foo;
-
-#[foo]
+#[recollect_attr]
 fn test1() {
     let a: i32 = "foo";
     //~^ ERROR: mismatched types
@@ -15,13 +14,13 @@ fn test1() {
 }
 
 fn test2() {
-    #![foo]
+    #![recollect_attr]
 
     // FIXME: should have a type error here and assert it works but it doesn't
 }
 
 trait A {
-    // FIXME: should have a #[foo] attribute here and assert that it works
+    // FIXME: should have a #[recollect_attr] attribute here and assert that it works
     fn foo(&self) {
         let a: i32 = "foo";
         //~^ ERROR: mismatched types
@@ -31,13 +30,13 @@ trait A {
 struct B;
 
 impl A for B {
-    #[foo]
+    #[recollect_attr]
     fn foo(&self) {
         let a: i32 = "foo";
         //~^ ERROR: mismatched types
     }
 }
 
-#[foo]
+#[recollect_attr]
 fn main() {
 }