Rollup merge of rust-lang#147813 - JonathanBrouwer:unused_attributes, r=jdonszelmann

Warn on unused_attributes in uitests

r? ```@jdonszelmann```

Because:
- unused_attributes warnings are usually actual mistakes, rather than just unused code, and we want to notify test writers they may be accidentally making a mistake
- Because the lint was allowed by default previously, we missed real bugs, because the test coverage is worse
  1. rust-lang#147417
  2. rust-lang#147411

Author: matthiaskrgr

src/tools/compiletest/src/runtest.rs

@@ -1838,8 +1838,9 @@ impl<'test> TestCx<'test> {
 
         // Add `-A unused` before `config` flags and in-test (`props`) flags, so that they can
         // overwrite this.
+        // Don't allow `unused_attributes` since these are usually actual mistakes, rather than just unused code.
         if let AllowUnused::Yes = allow_unused {
-            rustc.args(&["-A", "unused"]);
+            rustc.args(&["-A", "unused", "-W", "unused_attributes"]);
         }
 
         // Allow tests to use internal features.

tests/ui/attributes/attr-mix-new.rs

@@ -5,6 +5,7 @@
 #[rustc_dummy(bar)]
 mod foo {
   #![feature(globs)]
+  //~^ WARN crate-level attribute should be in the root module
 }
 
 fn main() {}

tests/ui/attributes/attr-mix-new.stderr

@@ -0,0 +1,10 @@
+warning: crate-level attribute should be in the root module
+  --> $DIR/attr-mix-new.rs:7:3
+   |
+LL |   #![feature(globs)]
+   |   ^^^^^^^^^^^^^^^^^^
+   |
+   = note: requested on the command line with `-W unused-attributes`
+
+warning: 1 warning emitted
+

tests/ui/attributes/crate-type-macro-empty.rs

@@ -1,6 +1,7 @@
 // Tests for the issue in #137589
 #[crate_type = foo!()]
 //~^ ERROR cannot find macro `foo` in this scope
+//~| WARN crate-level attribute should be an inner attribute
 
 macro_rules! foo {} //~ ERROR macros must contain at least one rule
 

tests/ui/attributes/crate-type-macro-empty.stderr

@@ -1,5 +1,5 @@
 error: macros must contain at least one rule
-  --> $DIR/crate-type-macro-empty.rs:5:1
+  --> $DIR/crate-type-macro-empty.rs:6:1
    |
 LL | macro_rules! foo {}
    | ^^^^^^^^^^^^^^^^^^^
@@ -11,10 +11,22 @@ LL | #[crate_type = foo!()]
    |                ^^^ consider moving the definition of `foo` before this call
    |
 note: a macro with the same name exists, but it appears later
-  --> $DIR/crate-type-macro-empty.rs:5:14
+  --> $DIR/crate-type-macro-empty.rs:6:14
    |
 LL | macro_rules! foo {}
    |              ^^^
 
-error: aborting due to 2 previous errors
+warning: crate-level attribute should be an inner attribute
+  --> $DIR/crate-type-macro-empty.rs:2:1
+   |
+LL | #[crate_type = foo!()]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: requested on the command line with `-W unused-attributes`
+help: add a `!`
+   |
+LL | #![crate_type = foo!()]
+   |  +
+
+error: aborting due to 2 previous errors; 1 warning emitted
 

tests/ui/attributes/crate-type-macro-not-found.rs

@@ -1,5 +1,6 @@
 // Tests for the issue in #137589
 #[crate_type = foo!()] //~ ERROR cannot find macro `foo` in this scope
+//~| WARN crate-level attribute should be an inner attribute
 
 macro_rules! foo {
     ($x:expr) => {"rlib"}

tests/ui/attributes/crate-type-macro-not-found.stderr

@@ -5,10 +5,22 @@ LL | #[crate_type = foo!()]
    |                ^^^ consider moving the definition of `foo` before this call
    |
 note: a macro with the same name exists, but it appears later
-  --> $DIR/crate-type-macro-not-found.rs:4:14
+  --> $DIR/crate-type-macro-not-found.rs:5:14
    |
 LL | macro_rules! foo {
    |              ^^^
 
-error: aborting due to 1 previous error
+warning: crate-level attribute should be an inner attribute
+  --> $DIR/crate-type-macro-not-found.rs:2:1
+   |
+LL | #[crate_type = foo!()]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: requested on the command line with `-W unused-attributes`
+help: add a `!`
+   |
+LL | #![crate_type = foo!()]
+   |  +
+
+error: aborting due to 1 previous error; 1 warning emitted
 

tests/ui/attributes/inline/attr-usage-inline.rs

@@ -9,16 +9,22 @@ struct S;
 
 struct I {
     #[inline]
+    //~^ WARN attribute cannot be used on
+    //~| WARN previously accepted
     i: u8,
 }
 
 #[macro_export]
 #[inline]
+//~^ WARN attribute cannot be used on
+//~| WARN previously accepted
 macro_rules! m_e {
     () => {};
 }
 
 #[inline] //~ ERROR: attribute should be applied to function or closure
+//~^ WARN attribute cannot be used on
+//~| WARN previously accepted
 macro_rules! m {
     () => {};
 }

tests/ui/attributes/inline/attr-usage-inline.stderr

@@ -7,11 +7,39 @@ LL | #[inline]
    = help: `#[inline]` can only be applied to functions
 
 error[E0518]: attribute should be applied to function or closure
-  --> $DIR/attr-usage-inline.rs:21:1
+  --> $DIR/attr-usage-inline.rs:25:1
    |
 LL | #[inline]
    | ^^^^^^^^^ not a function or closure
 
-error: aborting due to 2 previous errors
+warning: `#[inline]` attribute cannot be used on struct fields
+  --> $DIR/attr-usage-inline.rs:11:5
+   |
+LL |     #[inline]
+   |     ^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[inline]` can only be applied to functions
+   = note: requested on the command line with `-W unused-attributes`
+
+warning: `#[inline]` attribute cannot be used on macro defs
+  --> $DIR/attr-usage-inline.rs:18:1
+   |
+LL | #[inline]
+   | ^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[inline]` can only be applied to functions
+
+warning: `#[inline]` attribute cannot be used on macro defs
+  --> $DIR/attr-usage-inline.rs:25:1
+   |
+LL | #[inline]
+   | ^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = help: `#[inline]` can only be applied to functions
+
+error: aborting due to 2 previous errors; 3 warnings emitted
 
 For more information about this error, try `rustc --explain E0518`.

tests/ui/attributes/link-dl.rs

@@ -9,7 +9,7 @@
 //@ revisions: default_fcw allowed
 //@[allowed] check-pass
 
-#[cfg_attr(allowed, allow(ill_formed_attribute_input))]
+#![cfg_attr(allowed, allow(ill_formed_attribute_input))]
 
 #[link="dl"]
 //[default_fcw]~^ ERROR valid forms for the attribute are