Sema: Diagnose missing imports in resolveDeclRefExpr().

Author: tshortli

lib/Sema/PreCheckExpr.cpp

@@ -521,9 +521,14 @@ Expr *TypeChecker::resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE,
     if (inaccessibleResults) {
       // FIXME: What if the unviable candidates have different levels of access?
       const ValueDecl *first = inaccessibleResults.front().getValueDecl();
-      Context.Diags.diagnose(
-          Loc, diag::candidate_inaccessible, first,
-          first->getFormalAccessScope().accessLevelForDiagnostics());
+      auto accessLevel =
+          first->getFormalAccessScope().accessLevelForDiagnostics();
+      if (accessLevel == AccessLevel::Public &&
+          diagnoseMissingImportForMember(first, DC, Loc))
+        return errorResult();
+
+      Context.Diags.diagnose(Loc, diag::candidate_inaccessible, first,
+                             accessLevel);
 
       // FIXME: If any of the candidates (usually just one) are in the same
       // module we could offer a fix-it.

test/NameLookup/Inputs/members_A.swift

@@ -15,6 +15,8 @@ infix operator <>
 extension X {
   public func XinA() { }
 
+  public var propXinA: Bool { return true }
+
   public static func <<<(a: Self, b: Self) -> Self { a }
 }
 

test/NameLookup/Inputs/members_B.swift

@@ -4,6 +4,8 @@ import members_A
 extension X {
   public func XinB() { }
 
+  public var propXinB: Bool { return true }
+
   public static func >>>(a: Self, b: Self) -> Self { b }
 }
 

test/NameLookup/Inputs/members_C.swift

@@ -5,6 +5,8 @@ import members_B
 extension X {
   public func XinC() { }
 
+  public var propXinC: Bool { return true }
+
   public static func <>(a: Self, b: Self) -> Self { a }
 }
 

test/NameLookup/members_transitive.swift

@@ -38,3 +38,12 @@ func testMembersWithContextualBase() {
   takesEnumInC(.caseInC)
 }
 
+extension X {
+  var testProperties: (Bool, Bool, Bool) {
+    return (
+      propXinA,
+      propXinB, // expected-member-visibility-error{{property 'propXinB' is not available due to missing import of defining module 'members_B'}}
+      propXinC
+    )
+  }
+}