@Override
			void check(PcodeParser parser, String name) {
				// TODO: Also check the type is compatible?
				SleighSymbol symbol = parser.findSymbol(name);
				if (symbol == null) {
					throw new SleighException("Missing symbol '" + name + "'");
				}
			}
The name must already be defined by the language so it can be imported
Ghidra/Features/SystemEmulation/src/main/java/ghidra/pcode/struct/DefaultVar.java