Lambda to anonymous function: use callable builder (KT-7710)

idea/src/org/jetbrains/kotlin/idea/intentions/LambdaToAnonymousFunctionIntention.kt

@@ -42,22 +42,32 @@ class LambdaToAnonymousFunctionIntention : SelfTargetingIntention<KtLambdaExpres
             if (it.getTargetFunctionDescriptor(context) == descriptor) it.labeledExpression?.delete()
         }
 
-        val extension = descriptor.extensionReceiverParameter?.type?.let { "$it." } ?: ""
-        val params = descriptor.valueParameters.joinToString { "${it.name}: ${it.type}" }
-        val returnType = descriptor.returnType?.let { if (it.isUnit()) "" else ": $it" } ?: ""
-        if (returnType.isNotEmpty()) {
-            val lastStatement = bodyExpression.statements.lastOrNull()
-            if (lastStatement != null && lastStatement !is KtReturnExpression) {
-                val foldableReturns = BranchedFoldingUtils.getFoldableReturns(lastStatement)
-                if (foldableReturns == null || foldableReturns.isEmpty()) {
-                    lastStatement.replace(psiFactory.createExpressionByPattern("return $0", lastStatement))
+        // TODO: check type rendering (!!!)
+        val anonymousFunction = psiFactory.createFunction(
+            KtPsiFactory.CallableBuilder(KtPsiFactory.CallableBuilder.Target.FUNCTION).apply {
+                typeParams()
+                descriptor.extensionReceiverParameter?.type?.let {
+                    receiver(it.toString())
                 }
-            }
-        }
-        val anonymousFunction = element.replaced(
-            psiFactory.createExpressionByPattern("fun $0($1)$2 { $3 }", extension, params, returnType, bodyExpression, reformat = false)
-        ) as KtNamedFunction
+                name("")
+                for (parameter in descriptor.valueParameters) {
+                    param(parameter.name.asString(), parameter.type.toString())
+                }
+                descriptor.returnType?.takeIf { !it.isUnit() }?.let {
+                    val lastStatement = bodyExpression.statements.lastOrNull()
+                    if (lastStatement != null && lastStatement !is KtReturnExpression) {
+                        val foldableReturns = BranchedFoldingUtils.getFoldableReturns(lastStatement)
+                        if (foldableReturns == null || foldableReturns.isEmpty()) {
+                            lastStatement.replace(psiFactory.createExpressionByPattern("return $0", lastStatement))
+                        }
+                    }
+                    returnType(it.toString())
+                } ?: noReturnType()
+                blockBody(" " + bodyExpression.text)
+            }.asString()
+        )
 
-        (anonymousFunction.parent as? KtLambdaArgument)?.also { it.moveInsideParentheses(it.analyze(BodyResolveMode.PARTIAL)) }
+        val resultingFunction = element.replaced(anonymousFunction)
+        (resultingFunction.parent as? KtLambdaArgument)?.also { it.moveInsideParentheses(it.analyze(BodyResolveMode.PARTIAL)) }
     }
 }

idea/testData/intentions/lambdaToAnonymousFunction/argument.kt.after

@@ -1,5 +1,7 @@
 fun foo(f: (Int) -> String) {}
 
 fun test() {
-    foo(fun(it: Int): String { return "" })
+    foo(fun(it: Int): String {
+        return ""
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/explicitParameterName.kt.after

@@ -1,5 +1,7 @@
 fun bar(f: (Int, Int) -> String) {}
 
 fun test() {
-    bar(fun(i: Int, j: Int): String { return "$i$j" })
+    bar(fun(i: Int, j: Int): String {
+        return "$i$j"
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/extention1.kt.after

@@ -2,5 +2,7 @@ class Foo
 fun bar(f: Foo.() -> Unit) {}
 
 fun main(args: Array<String>) {
-    bar(fun Foo.() {})
+    bar(fun Foo.() {
+
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/extention2.kt.after

@@ -2,5 +2,7 @@ class Foo
 fun baz(f: Foo.(i: Int, j: Int) -> Int) {}
 
 fun main(args: Array<String>) {
-    baz(fun Foo.(i: Int, j: Int): Int { return i + j })
+    baz(fun Foo.(i: Int, j: Int): Int {
+        return i + j
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/hasReturn1.kt.after

@@ -1,5 +1,7 @@
 fun foo(f: (Int) -> String) {}
 
 fun test() {
-    foo(fun(it: Int): String { return "$it" })
+    foo(fun(it: Int): String {
+        return "$it"
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/implicitParameterName.kt.after

@@ -1,5 +1,7 @@
 fun foo(f: (Int) -> String) {}
 
 fun test() {
-    foo(fun(it: Int): String { return "$it" })
+    foo(fun(it: Int): String {
+        return "$it"
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/namedArgument.kt.after

@@ -1,5 +1,7 @@
 fun baz(name: String, f: (Int) -> String) {}
 
 fun test() {
-    baz(name = "", f = fun(it: Int): String { return "$it" })
+    baz(name = "", f = fun(it: Int): String {
+        return "$it"
+    })
 }

idea/testData/intentions/lambdaToAnonymousFunction/noParameter.kt.after

@@ -1,5 +1,7 @@
 fun foo(f: () -> String) {}
 
 fun test() {
-    foo(fun(): String { return "" })
+    foo(fun(): String {
+        return ""
+    })
 }