prevent items from macro expansions triggering lint

Author: jonboh

clippy_lints/src/unnecessary_map_on_constructor.rs

@@ -48,6 +48,9 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMapOnConstructor {
                     && let hir::ExprKind::Path(constructor_path) = constructor.kind
                     && let Some(arg) = constructor_args.get(0)
                 {
+                    if constructor.span.from_expansion() || arg.span.from_expansion() {
+                        return;
+                    }
                     (constructor_path, arg)
                 } else {
                     return;
@@ -69,9 +72,12 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMapOnConstructor {
                 _ => return,
             }
 
-            if let Some(arg) = args.get(0)
-                && let hir::ExprKind::Path(fun) = arg.kind
+            if let Some(map_arg) = args.get(0)
+                && let hir::ExprKind::Path(fun) = map_arg.kind
             {
+                if map_arg.span.from_expansion() {
+                    return;
+                }
                 let mut applicability = Applicability::MachineApplicable;
                 let constructor_snippet =
                     snippet_with_applicability(cx, constructor_path.span(), "_", &mut applicability);