Basic support of partially specified type arguments though a new underscore operator for type arguments

^KT-13394

compiler/frontend/src/org/jetbrains/kotlin/checkers/utils/DebugInfoUtil.kt

@@ -150,7 +150,7 @@ object DebugInfoUtil {
                         target = "[" + labelTargets.size + " elements]"
                     }
                 }
-                if (MAY_BE_UNRESOLVED.contains(referencedNameElementType)) {
+                if (MAY_BE_UNRESOLVED.contains(referencedNameElementType) || (expression is KtNameReferenceExpression && expression.isPlaceholder)) {
                     return
                 }
                 val resolved = target != null

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/NewCallArguments.kt

@@ -286,16 +286,24 @@ private fun resolveParametersTypes(
     }
 }
 
+@JvmName("resolveTypeWithGivenTypeReference")
+internal fun resolveType(
+    context: BasicCallResolutionContext,
+    typeReference: KtTypeReference,
+    typeResolver: TypeResolver
+): UnwrappedType {
+    val type = typeResolver.resolveType(context.scope, typeReference, context.trace, checkBounds = true)
+    ForceResolveUtil.forceResolveAllContents(type)
+    return type.unwrap()
+}
+
 internal fun resolveType(
     context: BasicCallResolutionContext,
     typeReference: KtTypeReference?,
     typeResolver: TypeResolver
 ): UnwrappedType? {
     if (typeReference == null) return null
-
-    val type = typeResolver.resolveType(context.scope, typeReference, context.trace, checkBounds = true)
-    ForceResolveUtil.forceResolveAllContents(type)
-    return type.unwrap()
+    return resolveType(context, typeReference, typeResolver)
 }
 
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/PSICallResolver.kt

@@ -687,8 +687,11 @@ class PSICallResolver(
             }
             ModifierCheckerCore.check(projection, context.trace, null, languageVersionSettings)
 
-            resolveType(context, projection.typeReference, typeResolver)?.let { SimpleTypeArgumentImpl(projection, it) }
-                ?: TypeArgumentPlaceholder
+            val typeReference = projection.typeReference
+
+            if (typeReference == null || typeReference.isPlaceholder) return@map TypeArgumentPlaceholder
+
+            SimpleTypeArgumentImpl(projection, resolveType(context, typeReference, typeResolver))
         }
 
     private fun resolveArgumentsInParenthesis(