Introduce inspection for safe cast + return #KT-26230 Fixed

idea/testData/inspectionsLocal/safeCastWithReturn/.inspection

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

idea/testData/inspectionsLocal/safeCastWithReturn/castNeverSucceeds.kt

@@ -0,0 +1,4 @@
+// PROBLEM: none
+fun test(x: Int) {
+    <caret>x as? String ?: return
+}

idea/testData/inspectionsLocal/safeCastWithReturn/hasParenthesize.kt

@@ -0,0 +1,6 @@
+fun test(x: Any): Int? {
+    <caret>(x as? String) ?: (return null)
+    return foo(x)
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/hasParenthesize.kt.after

@@ -0,0 +1,6 @@
+fun test(x: Any): Int? {
+    if (x !is String) return null
+    return foo(x)
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/labeledReturn.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+fun test(list: List<Any>) {
+    list.mapNotNull {
+        it as? String ?: return@mapNotNull null<caret>
+        foo(it)
+    }
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/labeledReturn.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+fun test(list: List<Any>) {
+    list.mapNotNull {
+        if (it !is String) return@mapNotNull null
+        foo(it)
+    }
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/simple.kt

@@ -0,0 +1,6 @@
+fun test(x: Any): Int? {
+    <caret>x as? String ?: return null
+    return foo(x)
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/simple.kt.after

@@ -0,0 +1,6 @@
+fun test(x: Any): Int? {
+    if (x !is String) return null
+    return foo(x)
+}
+
+fun foo(x: String) = 1

idea/testData/inspectionsLocal/safeCastWithReturn/usedAsExpression.kt

@@ -0,0 +1,7 @@
+// PROBLEM: none
+fun test(x: Any): Int? {
+    val s = <caret>x as? String ?: return null
+    return foo(s)
+}
+
+fun foo(x: String) = 1