Fixed KT-5020 Smart completion should work at the initializer of a val with no explicit type

#KT-5020 Fixed

idea/src/org/jetbrains/jet/plugin/completion/CompletionSession.java

@@ -144,7 +144,7 @@ class CompletionSession {
                 return isVisibleDescriptor(descriptor);
             }
         };
-        SmartCompletion completion = new SmartCompletion(jetReference.getExpression(), getResolveSession(), visibilityFilter);
+        SmartCompletion completion = new SmartCompletion(jetReference.getExpression(), getResolveSession(), visibilityFilter, (JetFile)parameters.getOriginalFile());
         Collection<LookupElement> elements = completion.buildLookupElements(descriptors);
         if (elements != null) {
             for (LookupElement element : elements) {

idea/src/org/jetbrains/jet/plugin/completion/smart/SmartCompletion.kt

@@ -29,10 +29,13 @@ import org.jetbrains.jet.plugin.completion.*
 import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns
 import org.jetbrains.jet.plugin.util.makeNotNullable
 import org.jetbrains.jet.plugin.util.makeNullable
+import com.intellij.psi.util.PsiTreeUtil
+import org.jetbrains.jet.plugin.caches.resolve.getLazyResolveSession
 
 class SmartCompletion(val expression: JetSimpleNameExpression,
                       val resolveSession: ResolveSessionForBodies,
-                      val visibilityFilter: (DeclarationDescriptor) -> Boolean) {
+                      val visibilityFilter: (DeclarationDescriptor) -> Boolean,
+                      val originalFile: JetFile) {
 
     private val bindingContext = resolveSession.resolveToElement(expression)
     private val moduleDescriptor = resolveSession.getModuleDescriptor()
@@ -73,7 +76,7 @@ class SmartCompletion(val expression: JetSimpleNameExpression,
             receiver = null
         }
 
-        val allExpectedInfos = ExpectedInfos(bindingContext, moduleDescriptor).calculate(expressionWithType) ?: return null
+        val allExpectedInfos = calcExpectedInfos(expressionWithType) ?: return null
         val filteredExpectedInfos = allExpectedInfos.filter { !it.`type`.isError() }
         if (filteredExpectedInfos.isEmpty()) return null
 
@@ -125,6 +128,23 @@ class SmartCompletion(val expression: JetSimpleNameExpression,
         return result
     }
 
+    private fun calcExpectedInfos(expression: JetExpression): Collection<ExpectedInfo>? {
+        // if our expression is initializer of implicitly typed variable - take type of variable from original file
+        val varDeclaration = expression.getParent() as? JetVariableDeclaration
+        if (varDeclaration != null && expression == varDeclaration.getInitializer() && varDeclaration.getTypeRef() == null) {
+            val offset = varDeclaration.getTextRange()!!.getStartOffset()
+            val originalDeclaration = PsiTreeUtil.findElementOfClassAtOffset(originalFile, offset, javaClass<JetVariableDeclaration>(), true)
+            if (originalDeclaration != null) {
+                val variableDescriptor = originalDeclaration.getLazyResolveSession().resolveToDescriptor(originalDeclaration) as? VariableDescriptor
+                if (variableDescriptor != null) {
+                    return listOf(ExpectedInfo(variableDescriptor.getType(), null))
+                }
+            }
+        }
+
+        return ExpectedInfos(bindingContext, moduleDescriptor).calculate(expression)
+    }
+
     private fun calcItemsToSkip(expression: JetExpression): Set<DeclarationDescriptor> {
         val parent = expression.getParent()
         when(parent) {

idea/testData/completion/smart/ImplicitlyTypedValInitializer1.kt

@@ -0,0 +1,6 @@
+fun foo(p1: String, p2: Int) {
+    val v = <caret>"a"
+}
+
+// EXIST: p1
+// ABSENT: p2

idea/testData/completion/smart/ImplicitlyTypedValInitializer2.kt

@@ -0,0 +1,6 @@
+class A(s: String) {
+    val v = s.<caret>length()
+}
+
+// EXIST: size
+// ABSENT: substring

idea/tests/org/jetbrains/jet/completion/JvmSmartCompletionTestGenerated.java

@@ -231,6 +231,16 @@ public class JvmSmartCompletionTestGenerated extends AbstractJvmSmartCompletionT
         doTest("idea/testData/completion/smart/IfValueInBlock2.kt");
     }
     
+    @TestMetadata("ImplicitlyTypedValInitializer1.kt")
+    public void testImplicitlyTypedValInitializer1() throws Exception {
+        doTest("idea/testData/completion/smart/ImplicitlyTypedValInitializer1.kt");
+    }
+    
+    @TestMetadata("ImplicitlyTypedValInitializer2.kt")
+    public void testImplicitlyTypedValInitializer2() throws Exception {
+        doTest("idea/testData/completion/smart/ImplicitlyTypedValInitializer2.kt");
+    }
+    
     @TestMetadata("InElvisOperator1.kt")
     public void testInElvisOperator1() throws Exception {
         doTest("idea/testData/completion/smart/InElvisOperator1.kt");