Fix function converters and plural arguments when single expected (Sk…

…riptLang#4896)

* Make functions error for incorrect argument plurality (single expected, multiple provided)

src/main/java/ch/njol/skript/lang/function/ExprFunctionCall.java

@@ -18,54 +18,55 @@
  */
 package ch.njol.skript.lang.function;
 
-import org.bukkit.event.Event;
-import org.eclipse.jdt.annotation.Nullable;
-
 import ch.njol.skript.lang.Expression;
 import ch.njol.skript.lang.SkriptParser.ParseResult;
 import ch.njol.skript.lang.util.SimpleExpression;
+import ch.njol.skript.registrations.Converters;
+import ch.njol.skript.util.Utils;
 import ch.njol.util.Kleenean;
+import org.bukkit.event.Event;
+import org.eclipse.jdt.annotation.Nullable;
 
-/**
- * @author Peter Güttinger
- */
 public class ExprFunctionCall<T> extends SimpleExpression<T> {
 
-	private final FunctionReference<T> function;
-
-	public ExprFunctionCall(final FunctionReference<T> function) {
+	private final FunctionReference<?> function;
+	private final Class<? extends T>[] returnTypes;
+	private final Class<T> returnType;
+
+	@SuppressWarnings("unchecked")
+	public ExprFunctionCall(FunctionReference<T> function) {
 		this.function = function;
+		this.returnTypes = function.returnTypes;
+		this.returnType = (Class<T>) Utils.getSuperType(returnTypes);
 	}
-	
+
 	@Override
 	@Nullable
-	protected T[] get(final Event e) {
-		T[] returnValue = function.execute(e);
+	protected T[] get(Event e) {
+		Object[] returnValue = function.execute(e);
 		function.resetReturnValue();
-		return returnValue;
+		return Converters.convertArray(returnValue, returnTypes, returnType);
 	}
-	
+
 	@Override
 	public boolean isSingle() {
 		return function.isSingle();
 	}
-	
+
 	@Override
 	public Class<? extends T> getReturnType() {
-		Class<? extends T> type = function.getReturnType();
-		assert type != null : "validateFunction() let invalid reference pass";
-		return type;
+		return returnType;
 	}
-	
+
 	@Override
-	public String toString(@Nullable final Event e, final boolean debug) {
+	public String toString(@Nullable Event e, boolean debug) {
 		return function.toString(e, debug);
 	}
-	
+
 	@Override
-	public boolean init(final Expression<?>[] exprs, final int matchedPattern, final Kleenean isDelayed, final ParseResult parseResult) {
+	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parseResult) {
 		assert false;
 		return false;
 	}
-	
+
 }

src/main/java/ch/njol/skript/lang/function/FunctionReference.java

@@ -29,6 +29,7 @@
 import ch.njol.skript.log.RetainingLogHandler;
 import ch.njol.skript.log.SkriptLogger;
 import ch.njol.skript.registrations.Classes;
+import ch.njol.skript.registrations.Converters;
 import ch.njol.skript.util.LiteralUtils;
 import ch.njol.util.StringUtils;
 import ch.njol.util.coll.CollectionUtils;
@@ -84,7 +85,7 @@ public class FunctionReference<T> {
 	 * of the function signature.
 	 */
 	@Nullable
-	private final Class<? extends T>[] returnTypes;
+	final Class<? extends T>[] returnTypes;
 
 	/**
 	 * Node for {@link #validateFunction(boolean)} to use for logging.
@@ -147,7 +148,7 @@ public boolean validateFunction(boolean first) {
 				}
 				return false;
 			}
-			if (!CollectionUtils.containsAnySuperclass(returnTypes, rt.getC())) {
+			if (!Converters.converterExists(rt.getC(), returnTypes)) {
 				if (first) {
 					Skript.error("The returned value of the function '" + functionName + "', " + sign.returnType + ", is " + SkriptParser.notOfType(returnTypes) + ".");
 				} else {
@@ -224,6 +225,16 @@ public boolean validateFunction(boolean first) {
 						function = previousFunction;
 					}
 					return false;
+				} else if (p.single && !e.isSingle()) {
+					if (first) {
+						Skript.error("The " + StringUtils.fancyOrderNumber(i + 1) + " argument given to the function '" + functionName + "' is plural, "
+							+ "but a single argument was expected");
+					} else {
+						Skript.error("The function '" + functionName + "' was redefined with different, incompatible arguments, but is still used in other script(s)."
+							+ " These will continue to use the old version of the function until Skript restarts.");
+						function = previousFunction;
+					}
+					return false;
 				}
 				parameters[i] = e;
 			} finally {

src/test/skript/tests/regressions/4524-function call conversion.sk

@@ -0,0 +1,5 @@
+function functionCallConversion() :: item:
+	return stone named "abc"
+
+test "function call conversion":
+	assert name of functionCallConversion() is "abc" with "Name of item from function call failed"

src/test/skript/tests/regressions/4859-function error with plural argument for single parameter.sk

@@ -0,0 +1,5 @@
+function pluralArgSingleParam(a: string, b: number) :: number:
+	return 1
+
+test "function error with plural argument for single parameter":
+	assert pluralArgSingleParam(("abc", "def"), 1) is 1 to fail with "function call didn't error with plural argument when single expected"