feat(overload): add errors caused by overloads

src/decaf/error/AmbiguousNewDeclarationError.java

+package decaf.error;
+
+import java.util.Iterator;
+import java.util.List;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.type.Type;
+import decaf.utils.FuncUtils;
+
+public class AmbiguousNewDeclarationError extends DecafError {
+
+	Function func;
+	Function prev;
+
+	public AmbiguousNewDeclarationError (Function func, Function prev, Location location) {
+		super(location);
+
+		this.func = func;
+		this.prev = prev;
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "ambiguous new declaration of '" + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "' :\n";
+		msg += "        *** note  : previous declaration at " + prev.getLocation() + " : " + prev.getReturnType() +  " " + FuncUtils.getArgListString(prev.getName(), prev.getType().getArgList(), prev.isStatik()) + "\n";
+		return msg.trim();
+	}
+
+}

src/decaf/error/ConflictMainError.java

+package decaf.error;
+
+import java.util.List;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.utils.CommonUtils;
+import decaf.utils.FuncUtils;
+
+public class ConflictMainError extends DecafError {
+
+	Function func;
+	List<Function> prevList;
+
+	public ConflictMainError (Function func, List<Function> prevList, Location location) {
+		super(location);
+
+		this.func = func;
+		this.prevList = CommonUtils.copyList(prevList);
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "conflicting declaration of main function '" + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "' :\n";
+		for (Function prev : prevList) {
+			msg += "        *** note  : previous declaration at " + prev.getLocation() + " : " + prev.getReturnType() + " " + FuncUtils.getArgListString(prev.getName(), prev.getType().getArgList(), prev.isStatik()) + "\n";
+		}
+		return msg.trim();
+	}
+
+}

src/decaf/error/MethodCallAmbiguousError.java

+package decaf.error;
+
+import java.util.List;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.type.Type;
+import decaf.utils.CommonUtils;
+import decaf.utils.FuncUtils;
+
+public class MethodCallAmbiguousError extends DecafError {
+
+	String name;
+	List<Type> argList;
+	List<Function> functions;
+
+	public MethodCallAmbiguousError (String name, List<Type> argList, List<Function> functions, Location location) {
+		super(location);
+
+		this.name = name;
+		this.argList = CommonUtils.copyList(argList);
+		this.functions = CommonUtils.copyList(functions);
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "call of overloaded " + FuncUtils.getArgListString(name, argList, true) + " is ambiguous, candidates are :\n";
+		for (Function func : functions) {
+			msg += "        *** note  : candidate at " + func.getLocation() + " : " + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "\n";
+		}
+		return msg.trim();
+	}
+
+}

src/decaf/error/NoMatchMethodError.java

+package decaf.error;
+
+import java.util.Iterator;
+import java.util.List;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.type.Type;
+import decaf.utils.CommonUtils;
+import decaf.utils.FuncUtils;
+
+public class NoMatchMethodError extends DecafError {
+
+	String name;
+	List<Type> argList;
+	List<Function> functions;
+	List<DecafError> errors;
+
+	public NoMatchMethodError(String name, List<Type> argList, List<Function> functions, List<DecafError> errors, Location location) {
+		super(location);
+
+		this.name = name;
+		this.argList = CommonUtils.copyList(argList);
+		this.functions = CommonUtils.copyList(functions);
+		this.errors = CommonUtils.copyList(errors);
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "no match function for call to " + FuncUtils.getArgListString(name, argList, true) + ", candidates are :\n";
+		Iterator<DecafError> iter = errors.iterator();
+		for (Function func : functions) {
+			DecafError error = iter.next();
+			msg += "        *** note  : candidate at " + func.getLocation() + " : " + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "\n";
+			msg += "            error : " + error.getErrMsg() + "\n";
+		}
+		return msg.trim();
+	}
+
+}

src/decaf/error/RedefinitionError.java

+package decaf.error;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.utils.FuncUtils;
+
+public class RedefinitionError extends DecafError {
+
+	Function func;
+	Function prev;
+
+	public RedefinitionError (Function func, Function prev, Location location) {
+		super(location);
+
+		this.func = func;
+		this.prev = prev;
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "redefinition of '" + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "' :\n";
+		msg += "        *** note  : previous declaration at " + prev.getLocation() + " : " + prev.getReturnType() + " " + FuncUtils.getArgListString(prev.getName(), prev.getType().getArgList(), prev.isStatik()) + "\n";
+		return msg.trim();
+	}
+
+}

src/decaf/error/VarOverrideMethodError.java

+package decaf.error;
+
+import java.util.List;
+
+import decaf.Location;
+import decaf.symbol.Function;
+import decaf.type.Type;
+import decaf.utils.CommonUtils;
+import decaf.utils.FuncUtils;
+
+public class VarOverrideMethodError extends DecafError {
+
+	String name;
+	List<Function> functions;
+
+	public VarOverrideMethodError (String name, List<Function> functions, Location location) {
+		super(location);
+
+		this.name = name;
+		this.functions = CommonUtils.copyList(functions);
+	}
+
+	@Override
+	protected String getErrMsg() {
+		String msg = "declaration of '" + name
+			+ "' here conflicts with earlier declarations : \n";
+		for (Function func : functions) {
+			msg += "        *** note  : previously declared at " + func.getLocation() + " : " + func.getReturnType() + " " + FuncUtils.getArgListString(func.getName(), func.getType().getArgList(), func.isStatik()) + "\n";
+		}
+		return msg.trim();
+	}
+
+}

src/decaf/utils/CommonUtils.java

+package decaf.utils;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public final class CommonUtils
+{
+	public static final <T> List<T> copyList (List<T> list)
+	{
+		List<T> result = new ArrayList<>();
+		result.addAll(list);
+		return result;
+	}
+}
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