Test that unsafe extern defines unsafe fns

Author: spastorino

tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2021.stderr

@@ -0,0 +1,11 @@
+error[E0133]: call to unsafe function `test1` is unsafe and requires unsafe function or block
+  --> $DIR/extern-items-unsafe.rs:11:5
+   |
+LL |     test1(i);
+   |     ^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0133`.

tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.edition2024.stderr

@@ -0,0 +1,11 @@
+error[E0133]: call to unsafe function `test1` is unsafe and requires unsafe block
+  --> $DIR/extern-items-unsafe.rs:11:5
+   |
+LL |     test1(i);
+   |     ^^^^^^^^ call to unsafe function
+   |
+   = note: consult the function's documentation for information on how to avoid undefined behavior
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0133`.

tests/ui/rust-2024/unsafe-extern-blocks/extern-items-unsafe.rs

@@ -0,0 +1,21 @@
+//@ revisions: edition2021 edition2024
+//@[edition2021] edition:2021
+//@[edition2024] edition:2024
+//@[edition2024] compile-flags: -Zunstable-options
+
+unsafe extern "C" {
+    fn test1(i: i32);
+}
+
+fn test2(i: i32) {
+    test1(i);
+    //~^ ERROR: call to unsafe function `test1` is unsafe
+}
+
+fn test3(i: i32) {
+    unsafe {
+        test1(i);
+    }
+}
+
+fn main() {}