8340205: Native linker allows MemoryLayout consisting of only PaddingLayout

test/jdk/java/foreign/TestLinker.java

@@ -180,12 +180,9 @@ public void interwovenPadding() {
         var struct = MemoryLayout.structLayout(JAVA_BYTE, padding1, padding2, JAVA_INT);
 
         var fd = FunctionDescriptor.of(struct, struct, struct);
-        try {
-          linker.downcallHandle(fd);
-        } catch (IllegalArgumentException e) {
-            assertEquals(e.getMessage(),
-                    "The padding layout x2 was preceded by another padding layout x1 in [b1x1x2i4]");
-        }
+        var e = expectThrows(IllegalArgumentException.class, () -> linker.downcallHandle(fd));
+        assertEquals(e.getMessage(),
+                "The padding layout x2 was preceded by another padding layout x1 in [b1x1x2i4]");
     }
 
     @Test
@@ -201,12 +198,9 @@ public void stackedPadding() {
         var union = MemoryLayout.unionLayout(struct32, padding32);
         var struct = MemoryLayout.structLayout(JAVA_BYTE, padding1, padding2, padding4, padding8, padding16, union);
         var fd = FunctionDescriptor.of(struct, struct, struct);
-        try {
-            linker.downcallHandle(fd);
-        } catch (IllegalArgumentException e) {
-            assertEquals(e.getMessage(),
-                    "The padding layout x2 was preceded by another padding layout x1 in [b1x1x2x4x8x16[[[4:j8]]|x32]]");
-        }
+        var e = expectThrows(IllegalArgumentException.class, () -> linker.downcallHandle(fd));
+        assertEquals(e.getMessage(),
+                "The padding layout x2 was preceded by another padding layout x1 in [b1x1x2x4x8x16[[[4:j8]]|x32]]");
     }
 
     @Test