KT-19390: Fix char + String in Java is converted to code with multiple type errors in Kotlin (#1235)

#KT-19390 Fixed

j2k/src/org/jetbrains/kotlin/j2k/CodeConverter.kt

@@ -17,7 +17,6 @@
 package org.jetbrains.kotlin.j2k
 
 import com.intellij.psi.*
-import com.intellij.psi.CommonClassNames.*
 import org.jetbrains.kotlin.j2k.ast.*
 
 class CodeConverter(
@@ -112,10 +111,15 @@ class CodeConverter(
             convertedExpression = BangBangExpression.surroundIfNullable(convertedExpression)
         }
 
-        if (needConversion(actualType, expectedType)) {
+        if (actualType.needTypeConversion(expectedType)) {
             val expectedTypeStr = expectedType.canonicalText
             if (expression is PsiLiteralExpression) {
-                if (expectedTypeStr == "float" || expectedTypeStr == "double") {
+                if (actualType.canonicalText == "char" && expression.parent !is PsiExpressionList) {
+                    expression.getTypeConversionMethod(expectedType)?.also {
+                        convertedExpression = MethodCallExpression.buildNonNull(convertedExpression, it)
+                    }
+                }
+                else if (expectedTypeStr == "float" || expectedTypeStr == "double") {
                     var text = convertedExpression.canonicalCode()
                     if (text.last() in setOf('f', 'L')) {
                         text = text.substring(0, text.length - 1)
@@ -165,7 +169,7 @@ class CodeConverter(
                 resultType = resultType.toNotNullType()
             }
 
-            if (needConversion(actualType, expectedType)) {
+            if (actualType.needTypeConversion(expectedType)) {
                 val expectedTypeStr = expectedType.canonicalText
 
                 val willConvert = if (convertedExpression is LiteralExpression
@@ -186,21 +190,4 @@ class CodeConverter(
     private fun PsiPrefixExpression.isLiteralWithSign()
             = operand is PsiLiteralExpression && operationTokenType in setOf(JavaTokenType.PLUS, JavaTokenType.MINUS)
 
-    private fun needConversion(actual: PsiType, expected: PsiType): Boolean {
-        val expectedStr = expected.canonicalText
-        val actualStr = actual.canonicalText
-        return expectedStr != actualStr &&
-               expectedStr != typeConversionMap[actualStr] &&
-               actualStr != typeConversionMap[expectedStr]
-    }
-
-    private val typeConversionMap: Map<String, String> = mapOf(
-            JAVA_LANG_BYTE to "byte",
-            JAVA_LANG_SHORT to "short",
-            JAVA_LANG_INTEGER to "int",
-            JAVA_LANG_LONG to "long",
-            JAVA_LANG_FLOAT to "float",
-            JAVA_LANG_DOUBLE to "double",
-            JAVA_LANG_CHARACTER to "char"
-    )
 }

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

@@ -486,3 +486,37 @@ class TypeConverter(val converter: Converter) {
         private val mutableKotlinClasses = toKotlinMutableTypesMap.values.toSet()
     }
 }
+
+fun PsiExpression.getTypeConversionMethod(expectedType: PsiType): String? {
+    val actualType = this.type ?: return null
+    if (actualType == expectedType) return null
+    if (expectedType.canonicalText == CommonClassNames.JAVA_LANG_STRING) return "toString"
+    return when (expectedType) {
+        PsiType.BYTE -> "toByte"
+        PsiType.SHORT -> "toShort"
+        PsiType.INT -> "toInt"
+        PsiType.LONG -> "toLong"
+        PsiType.FLOAT -> "toFloat"
+        PsiType.DOUBLE -> "toDouble"
+        PsiType.CHAR -> "toChar"
+        else -> null
+    }
+}
+
+fun PsiType.needTypeConversion(expected: PsiType): Boolean {
+    val expectedStr = expected.canonicalText
+    val actualStr = canonicalText
+    return expectedStr != actualStr &&
+           expectedStr != typeConversionMap[actualStr] &&
+           actualStr != typeConversionMap[expectedStr]
+}
+
+private val typeConversionMap: Map<String, String> = mapOf(
+        CommonClassNames.JAVA_LANG_BYTE to "byte",
+        CommonClassNames.JAVA_LANG_SHORT to "short",
+        CommonClassNames.JAVA_LANG_INTEGER to "int",
+        CommonClassNames.JAVA_LANG_LONG to "long",
+        CommonClassNames.JAVA_LANG_FLOAT to "float",
+        CommonClassNames.JAVA_LANG_DOUBLE to "double",
+        CommonClassNames.JAVA_LANG_CHARACTER to "char"
+)

j2k/testData/fileOrElement/literalExpression/charToNumber.java

@@ -0,0 +1,8 @@
+public class CharToNumber {
+    private byte b = 'c';
+    private short s = 'c';
+    private int i = 'c';
+    private long l = 'c';
+    private float f = 'c';
+    private double d = 'c';
+}

j2k/testData/fileOrElement/literalExpression/charToNumber.kt

@@ -0,0 +1,8 @@
+class CharToNumber {
+    private val b: Byte = 'c'.toByte()
+    private val s: Short = 'c'.toShort()
+    private val i: Int = 'c'.toInt()
+    private val l: Long = 'c'.toLong()
+    private val f = 'c'.toFloat()
+    private val d = 'c'.toDouble()
+}

j2k/testData/fileOrElement/literalExpression/charToString.java

@@ -0,0 +1,7 @@
+public class CharToString {
+    private String value;
+
+    public String test() {
+        return '"' + value + '"';
+    }
+}

j2k/testData/fileOrElement/literalExpression/charToString.kt

@@ -0,0 +1,7 @@
+class CharToString {
+    private val value: String? = null
+
+    fun test(): String {
+        return '"'.toString() + value + '"'.toString()
+    }
+}

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -3359,6 +3359,18 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("charToNumber.java")
+        public void testCharToNumber() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/charToNumber.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("charToString.java")
+        public void testCharToString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/charToString.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("dollarInsideString.java")
         public void testDollarInsideString() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/dollarInsideString.java");

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -3359,6 +3359,18 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("charToNumber.java")
+        public void testCharToNumber() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/charToNumber.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("charToString.java")
+        public void testCharToString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/charToString.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("dollarInsideString.java")
         public void testDollarInsideString() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("j2k/testData/fileOrElement/literalExpression/dollarInsideString.java");