Uitests for external statics

tests/ui/eii/attribute_targets.stderr

@@ -1,106 +1,106 @@
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:7:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:9:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:13:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:15:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:21:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:23:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:27:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:29:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:32:5
    |
 LL |     #[foo]
    |     ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:34:5
    |
 LL |     #[eii]
    |     ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:39:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:41:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:44:5
    |
 LL |     #[foo]
    |     ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:46:5
    |
 LL |     #[eii]
    |     ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:51:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:53:1
    |
 LL | #[eii]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:56:5
    |
 LL |     #[foo]
    |     ^^^^^^
 
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/attribute_targets.rs:58:5
    |
 LL |     #[eii]

tests/ui/eii/default/call_default.rs

@@ -3,7 +3,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests EIIs with default implementations.
 // When there's no explicit declaration, the default should be called from the declaring crate.

tests/ui/eii/default/call_default_panics.rs

@@ -5,7 +5,7 @@
 //@ needs-unwind
 //@ exec-env:RUST_BACKTRACE=1
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // A small test to make sure that unwinding works properly.
 //

tests/ui/eii/default/call_impl.rs

@@ -4,7 +4,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests EIIs with default implementations.
 // When an explicit implementation is given in one dependency, and the declaration is in another,

tests/ui/eii/default/local_crate.rs

@@ -1,7 +1,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests EIIs with default implementations.
 // In the same crate, when there's no explicit declaration, the default should be called.

tests/ui/eii/default/local_crate_explicit.rs

@@ -1,7 +1,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests EIIs with default implementations.
 // In the same crate, the explicit implementation should get priority.

tests/ui/eii/duplicate/duplicate1.rs

@@ -2,7 +2,7 @@
 //@ aux-build: impl1.rs
 //@ aux-build: impl2.rs
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // tests that EIIs error properly, even if the conflicting implementations live in another crate.
 #![feature(extern_item_impls)]

tests/ui/eii/duplicate/duplicate2.rs

@@ -3,7 +3,7 @@
 //@ aux-build: impl2.rs
 //@ aux-build: impl3.rs
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests the error message when there are multiple implementations of an EII in many crates.
 #![feature(extern_item_impls)]

tests/ui/eii/duplicate/duplicate3.rs

@@ -4,7 +4,7 @@
 //@ aux-build: impl3.rs
 //@ aux-build: impl4.rs
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests the error message when there are multiple implementations of an EII in many crates.
 #![feature(extern_item_impls)]

tests/ui/eii/duplicate/multiple_impls.rs

@@ -1,7 +1,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests whether one function could implement two EIIs.
 #![feature(extern_item_impls)]

tests/ui/eii/error_statement_position.stderr

@@ -1,4 +1,4 @@
-error: `#[eii]` is only valid on functions
+error: `#[eii]` is only valid on functions and statics
   --> $DIR/error_statement_position.rs:8:5
    |
 LL |     #[eii]

tests/ui/eii/errors.rs

@@ -25,11 +25,9 @@ fn hello() {
     safe fn bar(x: u64) -> u64;
 }
 
-#[foo] //~ ERROR `#[foo]` is only valid on functions
-static X: u64 = 4;
-#[foo] //~ ERROR `#[foo]` is only valid on functions
+#[foo] //~ ERROR `#[foo]` is only valid on functions and statics
 const Y: u64 = 4;
-#[foo] //~ ERROR `#[foo]` is only valid on functions
+#[foo] //~ ERROR `#[foo]` is only valid on functions and statics
 macro bar() {}
 
 #[foo()]

tests/ui/eii/errors.stderr

@@ -52,47 +52,41 @@ error: `#[eii_declaration(...)]` expects a list of one or two elements
 LL | #[eii_declaration = "unsafe"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/errors.rs:28:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
+error: `#[foo]` is only valid on functions and statics
   --> $DIR/errors.rs:30:1
    |
 LL | #[foo]
    | ^^^^^^
 
-error: `#[foo]` is only valid on functions
-  --> $DIR/errors.rs:32:1
-   |
-LL | #[foo]
-   | ^^^^^^
-
 error: `#[foo]` expected no arguments or a single argument: `#[foo(default)]`
-  --> $DIR/errors.rs:35:1
+  --> $DIR/errors.rs:33:1
    |
 LL | #[foo()]
    | ^^^^^^^^
 
 error: `#[foo]` expected no arguments or a single argument: `#[foo(default)]`
-  --> $DIR/errors.rs:37:1
+  --> $DIR/errors.rs:35:1
    |
 LL | #[foo(default, bar)]
    | ^^^^^^^^^^^^^^^^^^^^
 
 error: `#[foo]` expected no arguments or a single argument: `#[foo(default)]`
-  --> $DIR/errors.rs:39:1
+  --> $DIR/errors.rs:37:1
    |
 LL | #[foo("default")]
    | ^^^^^^^^^^^^^^^^^
 
 error: `#[foo]` expected no arguments or a single argument: `#[foo(default)]`
-  --> $DIR/errors.rs:41:1
+  --> $DIR/errors.rs:39:1
    |
 LL | #[foo = "default"]
    | ^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 15 previous errors
+error: aborting due to 14 previous errors
 

tests/ui/eii/linking/codegen_cross_crate.rs

@@ -3,7 +3,7 @@
 //@ aux-build: codegen_cross_crate_other_crate.rs
 //@ compile-flags: -O
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests whether calling EIIs works with the declaration in another crate.
 

tests/ui/eii/linking/codegen_single_crate.rs

@@ -1,7 +1,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 // Tests whether calling EIIs works with the declaration in the same crate.
 #![feature(extern_item_impls)]

tests/ui/eii/linking/same-symbol.rs

@@ -1,7 +1,7 @@
 //@ run-pass
 //@ check-run-results
 //@ ignore-backends: gcc
-// FIXME: linking on windows (speciifcally mingw) not yet supported, see tracking issue #125418
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
 //@ ignore-windows
 #![feature(extern_item_impls)]
 

tests/ui/eii/shadow_builtin.rs

@@ -0,0 +1,17 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether calling EIIs works with the declaration in the same crate.
+#![feature(extern_item_impls)]
+
+#[eii(inline)]
+//~^ ERROR `#[inline]` required, but not found
+fn test(x: u64);
+
+#[inline]
+//~^ ERROR `inline` is ambiguous
+fn test_impl(x: u64) {
+    println!("{x:?}")
+}
+
+fn main() { }

tests/ui/eii/shadow_builtin.stderr

@@ -0,0 +1,26 @@
+error[E0659]: `inline` is ambiguous
+  --> $DIR/shadow_builtin.rs:11:3
+   |
+LL | #[inline]
+   |   ^^^^^^ ambiguous name
+   |
+   = note: ambiguous because of a name conflict with a builtin attribute
+   = note: `inline` could refer to a built-in attribute
+note: `inline` could also refer to the attribute macro defined here
+  --> $DIR/shadow_builtin.rs:7:1
+   |
+LL | #[eii(inline)]
+   | ^^^^^^^^^^^^^^
+   = help: use `crate::inline` to refer to this attribute macro unambiguously
+
+error: `#[inline]` required, but not found
+  --> $DIR/shadow_builtin.rs:7:7
+   |
+LL | #[eii(inline)]
+   |       ^^^^^^ expected because `#[inline]` was declared here in crate `shadow_builtin`
+   |
+   = help: expected at least one implementation in crate `shadow_builtin` or any of its dependencies
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0659`.

tests/ui/eii/static/argument_required.rs

@@ -0,0 +1,11 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii]
+//~^ ERROR `#[eii]` requires the name as an explicit argument when used on a static
+static HELLO: u64;
+
+fn main() { }

tests/ui/eii/static/argument_required.stderr

@@ -0,0 +1,8 @@
+error: `#[eii]` requires the name as an explicit argument when used on a static
+  --> $DIR/argument_required.rs:7:1
+   |
+LL | #[eii]
+   | ^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/auxiliary/cross_crate_decl.rs

@@ -0,0 +1,6 @@
+//@ no-prefer-dynamic
+#![crate_type = "rlib"]
+#![feature(extern_item_impls)]
+
+#[eii(eii1)]
+pub static DECL1: u64;

tests/ui/eii/static/auxiliary/cross_crate_def.rs

@@ -0,0 +1,9 @@
+//@ no-prefer-dynamic
+#![crate_type = "rlib"]
+#![feature(extern_item_impls)]
+
+#[eii(eii1)]
+pub static DECL1: u64;
+
+#[eii1]
+pub static EII1_IMPL: u64 = 5;

tests/ui/eii/static/cross_crate_decl.rs

@@ -0,0 +1,21 @@
+//@ run-pass
+//@ check-run-results
+//@ aux-build: cross_crate_decl.rs
+//@ compile-flags: -O
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether calling EIIs works with the declaration in another crate.
+
+extern crate cross_crate_decl as codegen;
+
+#[codegen::eii1]
+static EII1_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{}", EII1_IMPL);
+    // through the alias
+    println!("{}", codegen::DECL1);
+}

tests/ui/eii/static/cross_crate_decl.run.stdout

@@ -0,0 +1,2 @@
+5
+5

tests/ui/eii/static/cross_crate_def.rs

@@ -0,0 +1,18 @@
+//@ run-pass
+//@ check-run-results
+//@ aux-build: cross_crate_def.rs
+//@ compile-flags: -O
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether calling EIIs works with the declaration and definition in another crate.
+
+extern crate cross_crate_def as codegen;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{}", codegen::EII1_IMPL);
+    // through the alias
+    println!("{}", codegen::DECL1);
+}

tests/ui/eii/static/cross_crate_def.run.stdout

@@ -0,0 +1,2 @@
+5
+5

tests/ui/eii/static/duplicate.rs

@@ -0,0 +1,25 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static HELLO: u64;
+
+#[hello]
+static HELLO_IMPL1: u64 = 5;
+//~^ ERROR multiple implementations of `#[hello]`
+
+#[hello]
+static HELLO_IMPL2: u64 = 6;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{HELLO_IMPL1}");
+    println!("{HELLO_IMPL2}");
+
+    // through the alias
+    println!("{HELLO}");
+}

tests/ui/eii/static/duplicate.stderr

@@ -0,0 +1,13 @@
+error: multiple implementations of `#[hello]`
+  --> $DIR/duplicate.rs:11:1
+   |
+LL | static HELLO_IMPL1: u64 = 5;
+   | ^^^^^^^^^^^^^^^^^^^^^^^ first implemented here in crate `duplicate`
+...
+LL | static HELLO_IMPL2: u64 = 6;
+   | ----------------------- also implemented here in crate `duplicate`
+   |
+   = help: an "externally implementable item" can only have a single implementation in the final artifact. When multiple implementations are found, also in different crates, they conflict
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/mismatch_fn_static.rs

@@ -0,0 +1,14 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+fn hello() -> u64;
+
+#[hello]
+//~^ ERROR `#[hello]` must be used on a function
+static HELLO_IMPL: u64 = 5;
+
+fn main() { }

tests/ui/eii/static/mismatch_fn_static.stderr

@@ -0,0 +1,8 @@
+error: `#[hello]` must be used on a function
+  --> $DIR/mismatch_fn_static.rs:10:1
+   |
+LL | #[hello]
+   | ^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/mismatch_mut.rs

@@ -0,0 +1,21 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static mut HELLO: u64;
+
+#[hello]
+//~^ ERROR mutability does not match with the definition of`#[hello]`
+static HELLO_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{HELLO_IMPL}");
+
+    // through the alias
+    println!("{}", unsafe { HELLO });
+}

tests/ui/eii/static/mismatch_mut.stderr

@@ -0,0 +1,8 @@
+error: mutability does not match with the definition of`#[hello]`
+  --> $DIR/mismatch_mut.rs:10:1
+   |
+LL | #[hello]
+   | ^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/mismatch_safety.rs

@@ -0,0 +1,21 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+unsafe static mut HELLO: u64;
+
+#[hello]
+//~^ ERROR safety does not match with the definition of`#[hello]`
+static HELLO_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{HELLO_IMPL}");
+
+    // through the alias
+    println!("{}", unsafe { HELLO });
+}

tests/ui/eii/static/mismatch_safety.stderr

@@ -0,0 +1,8 @@
+error: safety does not match with the definition of`#[hello]`
+  --> $DIR/mismatch_safety.rs:10:1
+   |
+LL | #[hello]
+   | ^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/mismatch_static_fn.rs

@@ -0,0 +1,16 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static HELLO: u64;
+
+#[hello]
+//~^ ERROR `#[hello]` must be used on a static
+fn hello_impl() -> u64 {
+    5
+}
+
+fn main() { }

tests/ui/eii/static/mismatch_static_fn.stderr

@@ -0,0 +1,8 @@
+error: `#[hello]` must be used on a static
+  --> $DIR/mismatch_static_fn.rs:10:1
+   |
+LL | #[hello]
+   | ^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/eii/static/multiple_impls.rs

@@ -0,0 +1,21 @@
+//@ run-pass
+//@ check-run-results
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether one function could implement two EIIs.
+#![feature(extern_item_impls)]
+
+#[eii(a)]
+static A: u64;
+
+#[eii(b)]
+static B: u64;
+
+#[a]
+#[b]
+static IMPL: u64 = 5;
+
+fn main() {
+    println!("{A} {B} {IMPL}")
+}

tests/ui/eii/static/multiple_impls.run.stdout

@@ -0,0 +1 @@
+5 5 5

tests/ui/eii/static/mut.rs

@@ -0,0 +1,22 @@
+//@ run-pass
+//@ check-run-results
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static mut HELLO: u64;
+
+#[hello]
+static mut HELLO_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{}", unsafe { HELLO_IMPL });
+
+    // through the alias
+    println!("{}", unsafe { HELLO });
+}

tests/ui/eii/static/mut.run.stdout

@@ -0,0 +1,2 @@
+5
+5

tests/ui/eii/static/same_address.rs

@@ -0,0 +1,21 @@
+//@ run-pass
+//@ check-run-results
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs and their declarations share the same address
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static HELLO: u64;
+
+#[hello]
+static HELLO_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    assert_eq!(
+        &HELLO as *const u64 as usize,
+        &HELLO_IMPL as *const u64 as usize,
+    )
+}

tests/ui/eii/static/simple.rs

@@ -0,0 +1,22 @@
+//@ run-pass
+//@ check-run-results
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests whether EIIs work on statics
+#![feature(extern_item_impls)]
+
+#[eii(hello)]
+static HELLO: u64;
+
+#[hello]
+static HELLO_IMPL: u64 = 5;
+
+// what you would write:
+fn main() {
+    // directly
+    println!("{HELLO_IMPL}");
+
+    // through the alias
+    println!("{HELLO}");
+}

tests/ui/eii/static/simple.run.stdout

@@ -0,0 +1,2 @@
+5
+5

tests/ui/eii/static/subtype.rs

@@ -0,0 +1,18 @@
+//@ check-pass
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests that mismatching types of the declaration and definition are rejected
+#![feature(extern_item_impls)]
+
+use std::ptr;
+
+#[eii(hello)]
+static HELLO: for<'a> fn(&'a u8) -> &'a u8;
+
+#[hello]
+static HELLO_IMPL: for<'a> fn(&'a u8) -> &'static u8 = |_| todo!();
+
+fn main() {
+
+}

tests/ui/eii/static/subtype_wrong.rs

@@ -0,0 +1,17 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests that mismatching types of the declaration and definition are rejected
+#![feature(extern_item_impls)]
+
+use std::ptr;
+
+#[eii(hello)]
+static HELLO: for<'a> fn(&'a u8) -> &'static u8;
+
+#[hello]
+static HELLO_IMPL: for<'a> fn(&'a u8) -> &'a u8 = |_| todo!();
+//~^ ERROR mismatched types
+
+fn main() {
+}

tests/ui/eii/static/subtype_wrong.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/subtype_wrong.rs:13:1
+   |
+LL | static HELLO_IMPL: for<'a> fn(&'a u8) -> &'a u8 = |_| todo!();
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
+   |
+   = note: expected fn pointer `for<'a> fn(&'a _) -> &'static _`
+              found fn pointer `for<'a> fn(&'a _) -> &'a _`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.

tests/ui/eii/static/wrong_ty.rs

@@ -0,0 +1,18 @@
+//@ ignore-backends: gcc
+// FIXME: linking on windows (specifically mingw) not yet supported, see tracking issue #125418
+//@ ignore-windows
+// Tests that mismatching types of the declaration and definition are rejected
+#![feature(extern_item_impls)]
+
+use std::ptr;
+
+#[eii(hello)]
+static HELLO: u64;
+
+#[hello]
+static HELLO_IMPL: bool = true;
+//~^ ERROR static `HELLO_IMPL` has a type that is incompatible with the declaration of `#[hello]` [E0806]
+
+fn main() {
+
+}

tests/ui/eii/static/wrong_ty.stderr

@@ -0,0 +1,15 @@
+error[E0806]: static `HELLO_IMPL` has a type that is incompatible with the declaration of `#[hello]`
+  --> $DIR/wrong_ty.rs:13:1
+   |
+LL | static HELLO_IMPL: bool = true;
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: expected this because of this attribute
+  --> $DIR/wrong_ty.rs:12:1
+   |
+LL | #[hello]
+   | ^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0806`.