[FIX] Recursive function items: Typing. Closes #2314

basex-core/src/main/java/org/basex/query/QueryContext.java

@@ -99,9 +99,9 @@ public final class QueryContext extends Job implements Closeable {
   public boolean tco;
 
   /** Function for the next tail call. */
-  private XQFunction tcFunc;
+  public XQFunction tcFunc;
   /** Arguments for the next tail call. */
-  private Value[] tcArgs;
+  public Value[] tcArgs;
   /** Counter for variable IDs. */
   public int varIDs;
 
@@ -544,36 +544,6 @@ public void set(final Var var, final Value value) throws QueryException {
     stack.set(var, value, this);
   }
 
-  /**
-   * Registers a tail-called function and its arguments to this query context.
-   * @param fn function to call
-   * @param args arguments to pass to {@code fn}
-   */
-  public void registerTailCall(final XQFunction fn, final Value[] args) {
-    tcFunc = fn;
-    tcArgs = args;
-  }
-
-  /**
-   * Returns and clears the currently registered tail-call function.
-   * @return function to call if present, {@code null} otherwise
-   */
-  public XQFunction pollTailCall() {
-    final XQFunction fn = tcFunc;
-    tcFunc = null;
-    return fn;
-  }
-
-  /**
-   * Returns and clears registered arguments of a tail-called function.
-   * @return argument values if a tail call was registered, {@code null} otherwise
-   */
-  public Value[] pollTailArgs() {
-    final Value[] args = tcArgs;
-    tcArgs = null;
-    return args;
-  }
-
   /**
    * Initializes the static date and time context of a query if not done yet.
    * @return self reference

basex-core/src/main/java/org/basex/query/expr/TypeCheck.java

@@ -114,7 +114,8 @@ public Value value(final QueryContext qc) throws QueryException {
       if(!st.occ.check(value.size())) throw typeError(value, st, info);
       return value;
     }
-    return st.coerce(value, null, qc, null, info);
+    // ignore type of result returned by tail call function
+    return qc.tcFunc != null ? value : st.coerce(value, null, qc, null, info);
   }
 
   @Override

basex-core/src/main/java/org/basex/query/func/XQFunction.java

@@ -31,9 +31,12 @@ default Value invoke(final QueryContext qc, final InputInfo info, final Value...
       while(true) {
         qc.checkStop();
         final Value value = fn.invokeInternal(qc, info, values);
-        fn = qc.pollTailCall();
-        if(fn == null) return value;
-        values = qc.pollTailArgs();
+        if(qc.tcFunc == null) return value;
+        // call registered tail call function
+        fn = qc.tcFunc;
+        qc.tcFunc = null;
+        values = qc.tcArgs;
+        qc.tcArgs = null;
         qc.stack.reuseFrame(fn.stackFrameSize());
       }
     } catch(final QueryException ex) {
@@ -58,8 +61,9 @@ default Value invokeTail(final QueryContext qc, final InputInfo info, final Valu
     qc.checkStop();
     final int size = stackFrameSize();
     if(qc.tco && qc.stack.tco(size)) {
-      // too many tail calls on the stack, eliminate them
-      qc.registerTailCall(this, args);
+      // stack is full: register tail call function
+      qc.tcFunc = this;
+      qc.tcArgs = args;
       return Empty.VALUE;
     }
 

basex-core/src/test/java/org/basex/query/ast/RewritingsTest.java

@@ -3341,4 +3341,16 @@ private static String gh1852(final String query) {
     execute(new Add("4.xml", "<d/>"));
     query("db:get('" + NAME + "1'), db:get('" + NAME + "2')", "<a/>\n<b/>\n<c/>\n<d/>");
   }
+
+  /** Recursive function items: Typing. */
+  @Test public void gh2314() {
+    query("declare function local:f($p) as xs:integer {"
+        + " if($p < 100000) then local:f($p + 1) else $p"
+        + "};"
+        + "local:f(1)", 100000);
+     query("let $f := fn($p, $self) as xs:integer {"
+        + " if($p < 100000) then $self($p + 1, $self) else $p"
+        + "}"
+        + "return $f(1, $f)", 100000);
+  }
 }