fixed PY-9466 Wrong current parameter highlighting for the very first parameter in finction

regression, added test

python/src/com/jetbrains/python/PyParameterInfoHandler.java

@@ -178,7 +178,10 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
     // highlight the next parameter to be filled
     if (canOfferNext) {
       int highlightIndex = Integer.MAX_VALUE; // initially beyond reason = no highlight
-      if (lastParamIndex < parameterList.size() - 1) { // lastParamIndex not at end, or no args
+      if (isArgsEmpty) {
+        highlightIndex = marked.getImplicitOffset(); // no args, highlight first (PY-3690)
+      }
+      else if (lastParamIndex < parameterList.size() - 1) { // lastParamIndex not at end, or no args
         if (namedParameters.get(lastParamIndex).isPositionalContainer()) {
           highlightIndex = lastParamIndex; // stick to *arg
         }
@@ -186,9 +189,6 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
           highlightIndex = lastParamIndex + 1; // highlight next
         }
       }
-      else if (isArgsEmpty) {
-        highlightIndex = marked.getImplicitOffset(); // no args, highlight first (PY-3690)
-      }
       else if (lastParamIndex == parameterList.size() - 1) { // we're right after the end of param list
         if (namedParameters.get(lastParamIndex).isPositionalContainer() || namedParameters.get(lastParamIndex).isKeywordContainer()) {
           highlightIndex = lastParamIndex; // stick to *arg

python/testData/paramInfo/NoArgs.py

@@ -0,0 +1,4 @@
+def foo(a, b, c):
+    pass
+
+foo(<arg1>)

python/testSrc/com/jetbrains/python/PyParameterInfoTest.java

@@ -375,6 +375,11 @@ public class PyParameterInfoTest extends LightMarkedTestCase {
     feignCtrlP(marks.get("<arg4>").getTextOffset()).check("*arg, a=1, b=2", new String[]{"a=1, "});
   }
 
+  public void testNoArgs() {
+    Map<String, PsiElement> marks = loadTest(1);
+    feignCtrlP(marks.get("<arg1>").getTextOffset()).check("a, b, c", new String[]{"a, "});
+  }
+
   /**
    * Imitates pressing of Ctrl+P; fails if results are not as expected.
    * @param offset offset of 'cursor' where ^P is pressed.