add rustc_abi debugging attribute

compiler/rustc_passes/src/errors.rs

@@ -913,6 +913,15 @@ pub struct LayoutOf {
     pub ty_layout: String,
 }
 
+#[derive(Diagnostic)]
+#[diag(passes_abi_of)]
+pub struct AbiOf {
+    #[primary_span]
+    pub span: Span,
+    pub fn_name: Symbol,
+    pub fn_abi: String,
+}
+
 #[derive(Diagnostic)]
 #[diag(passes_unrecognized_field)]
 pub struct UnrecognizedField {