[CodeComplete] Avoid using an unresolved contextual type

This can occur for e.g multi-statement closure
returns (and soon for singe-expression closures
too), so fall back to evaluating the expression
type if it's not fully resolved.

Author: hamishknight

lib/IDE/TypeCheckCompletionCallback.cpp

@@ -47,8 +47,11 @@ void TypeCheckCompletionCallback::fallbackTypeCheck(DeclContext *DC) {
 
 Type swift::ide::getTypeForCompletion(const constraints::Solution &S,
                                       ASTNode Node) {
+  // Use the contextual type, unless it is still unresolved, in which case fall
+  // back to getting the type from the expression.
   if (auto ContextualType = S.getContextualType(Node)) {
-    return ContextualType;
+    if (!ContextualType->hasUnresolvedType())
+      return ContextualType;
   }
 
   if (!S.hasType(Node)) {

test/IDE/complete_issue-55711.swift

@@ -1,6 +1,4 @@
-// RUN: %swift-ide-test -code-completion -source-filename=%s -code-completion-token=A | %FileCheck %s --check-prefix=A
-// RUN: %swift-ide-test -code-completion -source-filename=%s -code-completion-token=B | %FileCheck %s --check-prefix=B
-// RUN: %swift-ide-test -code-completion -source-filename=%s -code-completion-token=D | %FileCheck %s --check-prefix=D
+// RUN: %batch-code-completion
 
 // https://github.com/apple/swift/issues/55711
 // https://forums.swift.org/t/code-completion-enhancement-request/38677
@@ -37,6 +35,10 @@ func test() {
   C(.a) {
     .#^A^#
   }
+  C(.a) {
+    ()
+    return .#^A_MULTISTMT?check=A^#
+  }
 // A: Begin completions, 2 items
 // A-DAG: Decl[StaticMethod]/CurrNominal/TypeRelation[Convertible]: foo({#arg: Bool#})[#A<X>#];
 // A-DAG: Decl[StaticMethod]/CurrNominal/TypeRelation[Convertible]: bar({#arg: Int#})[#A<Y>#];