Fixed KT-5434 J2K: incorrect conversion of main method

#KT-5434 Fixed

j2k/src/org/jetbrains/jet/j2k/MainMethodUtils.kt

@@ -16,80 +16,52 @@
 
 package org.jetbrains.jet.j2k
 
-import java.text.MessageFormat
 import com.intellij.psi.PsiMethod
 import com.intellij.psi.PsiClass
 import com.intellij.psi.PsiJavaFile
 import java.util.ArrayList
-import com.intellij.psi.PsiFile
 import com.intellij.psi.PsiAnonymousClass
 import com.intellij.psi.PsiModifier
 import com.intellij.psi.PsiType
 import com.intellij.psi.PsiArrayType
 
-fun createMainFunction(file: PsiFile): String {
+fun createMainFunction(file: PsiJavaFile): String {
     val classNamesWithMains = ArrayList<Pair<String, PsiMethod>>()
-    for (c in (file as PsiJavaFile).getClasses()) {
+    for (c in file.getClasses()) {
         val main = findMainMethod(c)
         val name = c.getName()
         if (name != null && main != null) {
-            classNamesWithMains.add(Pair(name, main))
+            classNamesWithMains.add(name to main)
         }
     }
 
-    if (classNamesWithMains.size() > 0) {
-        var className = classNamesWithMains[0].first
-        return MessageFormat.format("fun main(args : Array<String>) = {0}.main(args as Array<String?>?)", className)
+    if (classNamesWithMains.isNotEmpty()) {
+        var className = classNamesWithMains.first().first
+        return "fun main(args : Array<String>) = $className.main(args)"
     }
 
     return ""
-
 }
 
-private fun findMainMethod(aClass: PsiClass): PsiMethod? {
-    if (isMainClass(aClass)) {
-        return findMainMethod(aClass.findMethodsByName("main", false))
-    }
-    return null
-}
+private fun findMainMethod(aClass: PsiClass): PsiMethod?
+        = if (isMainClass(aClass)) aClass.findMethodsByName("main", false).firstOrNull { it.isMainMethod() } else null
 
-private fun isMainClass(psiClass: PsiClass): Boolean {
-    if (psiClass is PsiAnonymousClass)
-        return false
+private fun isMainClass(psiClass: PsiClass): Boolean
+        = psiClass !is PsiAnonymousClass &&
+            !psiClass.isInterface() &&
+            (psiClass.getContainingClass() == null || psiClass.hasModifierProperty(PsiModifier.STATIC))
 
-    if (psiClass.isInterface())
-        return false
+fun PsiMethod.isMainMethod(): Boolean {
+    if (getReturnType() != PsiType.VOID) return false
+    if (!hasModifierProperty(PsiModifier.STATIC)) return false
+    if (!hasModifierProperty(PsiModifier.PUBLIC)) return false
 
-    return psiClass.getContainingClass() == null || psiClass.hasModifierProperty(PsiModifier.STATIC)
+    val parameters = getParameterList().getParameters()
+    if (parameters.size != 1) return false
 
-}
-
-private fun findMainMethod(mainMethods: Array<PsiMethod>): PsiMethod? {
-    return mainMethods.find { isMainMethod(it) }
-}
-
-fun isMainMethod(method: PsiMethod): Boolean {
-    if (method.getContainingClass() == null)
-        return false
-
-    if (PsiType.VOID != method.getReturnType())
-        return false
-
-    if (!method.hasModifierProperty(PsiModifier.STATIC))
-        return false
-
-    if (!method.hasModifierProperty(PsiModifier.PUBLIC))
-        return false
-
-    val parameters = method.getParameterList().getParameters()
-    if (parameters.size != 1)
-        return false
-
-    val `type` = parameters[0].getType()
-    if (`type` !is PsiArrayType)
-        return false
+    val `type` = parameters.single().getType()
+    if (`type` !is PsiArrayType) return false
 
     val componentType = `type`.getComponentType()
     return componentType.equalsToText("java.lang.String")
 }
-

j2k/src/org/jetbrains/jet/j2k/TypeConverter.kt

@@ -29,6 +29,9 @@ import com.intellij.psi.CommonClassNames.JAVA_LANG_OBJECT
 import org.jetbrains.jet.j2k.ast.assignNoPrototype
 import org.jetbrains.jet.j2k.ast.ErrorType
 import com.intellij.codeInsight.NullableNotNullManager
+import org.jetbrains.jet.j2k.ast.ArrayType
+import org.jetbrains.jet.j2k.ast.ClassType
+import org.jetbrains.jet.j2k.ast.Identifier
 
 class TypeConverter(val settings: ConverterSettings, val conversionScope: ConversionScope) {
     private val nullabilityCache = HashMap<PsiElement, Nullability>()
@@ -59,8 +62,17 @@ class TypeConverter(val settings: ConverterSettings, val conversionScope: Conver
     public fun convertTypes(types: Array<PsiType>): List<Type>
             = types.map { convertType(it) }
 
-    public fun convertVariableType(variable: PsiVariable): Type
-            = convertType(variable.getType(), variableNullability(variable)).assignPrototype(variable.getTypeElement())
+    public fun convertVariableType(variable: PsiVariable): Type {
+        val result = if (variable.isMainMethodParameter()) {
+            ArrayType(ClassType(Identifier("String").assignNoPrototype(), listOf(), Nullability.NotNull, settings).assignNoPrototype(),
+                      Nullability.NotNull,
+                      settings)
+        }
+        else {
+            convertType(variable.getType(), variableNullability(variable))
+        }
+        return result.assignPrototype(variable.getTypeElement())
+    }
 
     public fun variableNullability(variable: PsiVariable): Nullability {
         val cached = nullabilityCache[variable]
@@ -108,6 +120,10 @@ class TypeConverter(val settings: ConverterSettings, val conversionScope: Conver
             return Nullability.Nullable
         }
 
+        if (nullability == Nullability.Default && variable.isMainMethodParameter() ) {
+            return Nullability.NotNull
+        }
+
         if (!conversionScope.contains(variable)) { // do not analyze usages out of our conversion scope
             if (variable is PsiParameter) {
                 // Object.equals corresponds to Any.equals which has nullable parameter:
@@ -158,6 +174,8 @@ class TypeConverter(val settings: ConverterSettings, val conversionScope: Conver
         return nullability
     }
 
+    private fun PsiVariable.isMainMethodParameter() = this is PsiParameter && (getDeclarationScope() as? PsiMethod)?.isMainMethod() ?: false
+
     public fun convertMethodReturnType(method: PsiMethod): Type
             = convertType(method.getReturnType(), methodNullability(method)).assignPrototype(method.getReturnTypeElement())
 

j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java

@@ -1391,6 +1391,16 @@ public class JavaToKotlinConverterTestGenerated extends AbstractJavaToKotlinConv
             doTest("j2k/tests/testData/ast/function/main.java");
         }
         
+        @TestMetadata("main2.java")
+        public void testMain2() throws Exception {
+            doTest("j2k/tests/testData/ast/function/main2.java");
+        }
+        
+        @TestMetadata("mainAndNullabilitySetting.java")
+        public void testMainAndNullabilitySetting() throws Exception {
+            doTest("j2k/tests/testData/ast/function/mainAndNullabilitySetting.java");
+        }
+        
         @TestMetadata("methodClassType.java")
         public void testMethodClassType() throws Exception {
             doTest("j2k/tests/testData/ast/function/methodClassType.java");

j2k/tests/testData/ast/function/main2.java

@@ -0,0 +1,5 @@
+//file
+public class A {
+    public static void main(String[] args) {
+    }
+}

j2k/tests/testData/ast/function/main2.kt

@@ -0,0 +1,7 @@
+public class A {
+    class object {
+        public fun main(args: Array<String>) {
+        }
+    }
+}
+fun main(args: Array<String>) = A.main(args)

j2k/tests/testData/ast/function/mainAndNullabilitySetting.java

@@ -0,0 +1,6 @@
+// !forceNotNullTypes: false
+//file
+public class A {
+    public static void main(String[] args) {
+    }
+}

j2k/tests/testData/ast/function/mainAndNullabilitySetting.kt

@@ -0,0 +1,8 @@
+// !forceNotNullTypes: false
+public class A {
+    class object {
+        public fun main(args: Array<String>) {
+        }
+    }
+}
+fun main(args: Array<String>) = A.main(args)

j2k/tests/testData/ast/issues/kt-638.kt

@@ -31,4 +31,4 @@ public class User {
         }
     }
 }
-fun main(args: Array<String>) = User.main(args as Array<String?>?)
+fun main(args: Array<String>) = User.main(args)

j2k/tests/testData/ast/issues/kt-871.kt

@@ -7,4 +7,4 @@ class Program {
         }
     }
 }
-fun main(args: Array<String>) = Program.main(args as Array<String?>?)
+fun main(args: Array<String>) = Program.main(args)

j2k/tests/testData/ast/switch/comlicatedFallDown.kt

@@ -83,4 +83,4 @@ public class SwitchDemo {
         }
     }
 }
-fun main(args: Array<String>) = SwitchDemo.main(args as Array<String?>?)
+fun main(args: Array<String>) = SwitchDemo.main(args)

j2k/tests/testData/ast/switch/emptySwitch.kt

@@ -11,4 +11,4 @@ public class NonDefault {
         }
     }
 }
-fun main(args: Array<String>) = NonDefault.main(args as Array<String?>?)
+fun main(args: Array<String>) = NonDefault.main(args)

j2k/tests/testData/ast/switch/fallDown.kt

@@ -13,4 +13,4 @@ public class SwitchDemo {
         }
     }
 }
-fun main(args: Array<String>) = SwitchDemo.main(args as Array<String?>?)
+fun main(args: Array<String>) = SwitchDemo.main(args)

j2k/tests/testData/ast/switch/kt-539.kt

@@ -25,4 +25,4 @@ public class SwitchDemo {
         }
     }
 }
-fun main(args: Array<String>) = SwitchDemo.main(args as Array<String?>?)
+fun main(args: Array<String>) = SwitchDemo.main(args)

j2k/tests/testData/ast/switch/nondefault.kt

@@ -13,4 +13,4 @@ public class NonDefault {
         }
     }
 }
-fun main(args: Array<String>) = NonDefault.main(args as Array<String?>?)
+fun main(args: Array<String>) = NonDefault.main(args)