Add inspection to simplify successive null checks #KT-14799 Fixed

idea/testData/inspectionsLocal/nullChecksToSafeCall/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.NullChecksToSafeCallInspection

idea/testData/inspectionsLocal/nullChecksToSafeCall/andCase.kt

@@ -0,0 +1,10 @@
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a<caret> != null && a.a != null && a.a.a != null && a.a.a.a != null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/andCase.kt.after

@@ -0,0 +1,10 @@
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a?.a?.a?.a != null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/function.kt

@@ -0,0 +1,7 @@
+class My {
+    fun foo(): String? = null
+}
+
+fun test(my: My?) {
+    if (<caret>my != null && my.foo() != null) {}
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/function.kt.after

@@ -0,0 +1,7 @@
+class My {
+    fun foo(): String? = null
+}
+
+fun test(my: My?) {
+    if (my?.foo() != null) {}
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/kotlinType.kt

@@ -0,0 +1,10 @@
+// PROBLEM: none
+
+class KotlinType
+class KotlinTypeInfo(val type: KotlinType?) {
+    fun foo(other: KotlinTypeInfo) {
+        if (<caret>type != null && other.type != null) {
+
+        }
+    }
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/longRightExpression.kt

@@ -0,0 +1,13 @@
+// PROBLEM: none
+
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    // Controversial case, better to do nothing here
+    if (a<caret> != null && a.a?.a != null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/orCase.kt

@@ -0,0 +1,10 @@
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a<caret> == null || a.a == null || a.a.a == null || a.a.a.a == null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/orCase.kt.after

@@ -0,0 +1,10 @@
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a?.a?.a?.a == null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/safeCall.kt

@@ -0,0 +1,11 @@
+
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a?.a<caret> != null && a.a.a != null) {
+ 
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/safeCall.kt.after

@@ -0,0 +1,11 @@
+
+fun main(args: Array<String>) {
+    val a: Testtt? = Testtt()
+    if (a?.a?.a != null) {
+
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/unstableChain.kt

@@ -0,0 +1,12 @@
+// PROBLEM: none
+var a: Testtt? = Testtt()
+
+fun main(args: Array<String>) {
+    if (a<caret> != null && a?.a != null) {
+ 
+    }
+}
+
+class Testtt {
+    val a: Testtt? = null
+}

idea/testData/inspectionsLocal/nullChecksToSafeCall/unstableExtensionInChain.kt

@@ -0,0 +1,12 @@
+// PROBLEM: none
+val a: Testtt? = Testtt()
+
+fun main(args: Array<String>) {
+    if (a<caret> != null && a.a != null) {
+
+    }
+}
+
+class Testtt
+
+val Testtt?.a: Testtt? get() = null