add regression test for issue #143987

tests/ui/attributes/align-on-fields-143987.rs

@@ -0,0 +1,30 @@
+// Regression test for issue https://github.com/rust-lang/rust/issues/143987
+// Ensure that using `#[align]` on struct fields produces an error
+// instead of causing an ICE (Internal Compiler Error)
+
+// FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
+#![feature(rustc_attrs)]
+#![feature(fn_align)]
+
+struct Data {
+    #[rustc_align(8)] //~ ERROR `#[rustc_align]` attribute cannot be used on struct fields
+    x: usize,
+}
+
+// Test with invalid type to match the original issue more closely
+struct DataInvalid {
+    #[rustc_align(8)] //~ ERROR `#[rustc_align]` attribute cannot be used on struct fields
+    x: usize8, //~ ERROR cannot find type `usize8` in this scope
+}
+
+// Test with tuple struct
+struct TupleData(
+    #[rustc_align(32)] //~ ERROR `#[rustc_align]` attribute cannot be used on struct fields
+    u32
+);
+
+// Test that it works correctly on functions (no error)
+#[rustc_align(16)]
+fn aligned_function() {}
+
+fn main() {}

tests/ui/attributes/align-on-fields-143987.stderr

@@ -0,0 +1,33 @@
+error[E0412]: cannot find type `usize8` in this scope
+  --> $DIR/align-on-fields-143987.rs:17:8
+   |
+LL |     x: usize8,
+   |        ^^^^^^ help: a builtin type with a similar name exists: `usize`
+
+error: `#[rustc_align]` attribute cannot be used on struct fields
+  --> $DIR/align-on-fields-143987.rs:10:5
+   |
+LL |     #[rustc_align(8)]
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = help: `#[rustc_align]` can only be applied to functions
+
+error: `#[rustc_align]` attribute cannot be used on struct fields
+  --> $DIR/align-on-fields-143987.rs:16:5
+   |
+LL |     #[rustc_align(8)]
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = help: `#[rustc_align]` can only be applied to functions
+
+error: `#[rustc_align]` attribute cannot be used on struct fields
+  --> $DIR/align-on-fields-143987.rs:22:5
+   |
+LL |     #[rustc_align(32)]
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = help: `#[rustc_align]` can only be applied to functions
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0412`.