change signature from usage fix: varargs processing (IDEA-58449)

java/java-impl/src/com/intellij/codeInsight/daemon/impl/quickfix/ChangeMethodSignatureFromUsageFix.java

@@ -238,6 +238,7 @@ public class ChangeMethodSignatureFromUsageFix implements IntentionAction {
       }
       int ei = 0;
       int pi = 0;
+      PsiParameter varargParam = targetMethod.isVarArgs() ? parameters[parameters.length - 1] : null;
       while (ei < expressions.length || pi < parameters.length) {
         PsiExpression expression = ei < expressions.length ? expressions[ei] : null;
         PsiParameter parameter = pi < parameters.length ? parameters[pi] : null;
@@ -248,7 +249,16 @@ public class ChangeMethodSignatureFromUsageFix implements IntentionAction {
           pi++;
           ei++;
         }
+        else if (isArgumentInVarargPosition(expressions, ei, varargParam, substitutor)) {
+          if (pi == parameters.length - 1) {
+            assert varargParam != null;
+            result.add(new ParameterInfoImpl(pi, varargParam.getName(), varargParam.getType()));
+          }
+          pi++;
+          ei++;
+        }
         else if (expression != null) {
+          if (varargParam != null && pi >= parameters.length) return null;
           PsiType exprType = RefactoringUtil.getTypeByExpression(expression);
           if (exprType == null) return null;
           JavaCodeStyleManager codeStyleManager = JavaCodeStyleManager.getInstance(expression.getProject());
@@ -257,7 +267,7 @@ public class ChangeMethodSignatureFromUsageFix implements IntentionAction {
           ei++;
         }
       }
-      if (result.size() != expressions.length) return null;
+      if (result.size() != expressions.length && varargParam == null) return null;
     }
     else {
       //parameter type changed
@@ -291,6 +301,17 @@ public class ChangeMethodSignatureFromUsageFix implements IntentionAction {
     return result.toArray(new ParameterInfoImpl[result.size()]);
   }
 
+  private static boolean isArgumentInVarargPosition(PsiExpression[] expressions, int ei, PsiParameter varargParam, PsiSubstitutor substitutor) {
+    if (varargParam == null) return false;
+    final PsiExpression expression = expressions[ei];
+    if (expression == null || TypeConversionUtil.areTypesAssignmentCompatible(substitutor.substitute(((PsiEllipsisType)varargParam.getType()).getComponentType()), expression)) {
+      final int lastExprIdx = expressions.length - 1;
+      if (ei == lastExprIdx) return true;
+      return expressions[lastExprIdx].getType() != PsiType.NULL;
+    }
+    return false;
+  }
+
   private static String suggestUniqueParameterName(JavaCodeStyleManager codeStyleManager,
                                                               PsiExpression expression,
                                                               PsiType exprType,

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeMethodSignatureFromUsage/afterVarargs1.java

@@ -0,0 +1,6 @@
+// "Change signature of 'f(int...)' to 'f(String, int...)'" "true"
+ public class S {
+     void f(String s, int... args) {
+     f("",1,1);
+     }
+ }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeMethodSignatureFromUsage/afterVarargs2.java

@@ -0,0 +1,6 @@
+// "Change signature of 'f(int...)' to 'f(String, int...)'" "true"
+ public class S {
+     void f(String s, int... args) {
+     f("",null);
+     }
+ }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeMethodSignatureFromUsage/beforeVarargs1.java

@@ -0,0 +1,6 @@
+// "Change signature of 'f(int...)' to 'f(String, int...)'" "true"
+ public class S {
+     void f(int... args) {
+     f("",1,1)<caret>;
+     }
+ }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeMethodSignatureFromUsage/beforeVarargs2.java

@@ -0,0 +1,6 @@
+// "Change signature of 'f(int...)' to 'f(String, int...)'" "true"
+ public class S {
+     void f(int... args) {
+     f("",null)<caret>;
+     }
+ }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/changeMethodSignatureFromUsage/beforeVarargs2Array.java

@@ -0,0 +1,6 @@
+// "Change signature of 'f(int...)' to 'f(int..., String)'" "false"
+ public class S {
+     void f(int... args) {
+     f(1,1, "")<caret>;
+     }
+ }