Merge pull request #1881 from apple/dl/lldb-Stop-unconditionally-emitting-could-not-resolve-type

[lldb] Stop unconditionally emitting "could not resolve type"

Author: fredriss

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -7923,8 +7923,7 @@ void SwiftASTContext::DumpTypeDescription(opaque_compiler_type_t type,
                                           bool print_help_if_available,
                                           bool print_extensions_if_available,
                                           lldb::DescriptionLevel level) {
-  llvm::SmallVector<char, 1024> buf;
-  llvm::raw_svector_ostream llvm_ostrm(buf);
+  const auto initial_written_bytes = s->GetWrittenBytes();
 
   if (type) {
     swift::CanType swift_can_type(GetCanonicalSwiftType(type));
@@ -8088,12 +8087,10 @@ void SwiftASTContext::DumpTypeDescription(opaque_compiler_type_t type,
       }
     } break;
     }
-
-    if (buf.size() > 0) {
-      s->Write(buf.data(), buf.size());
-    }
   }
-  s->Printf("<could not resolve type>");
+
+  if (s->GetWrittenBytes() == initial_written_bytes)
+    s->Printf("<could not resolve type>");
 }
 
 TypeSP SwiftASTContext::GetCachedType(ConstString mangled) {

lldb/test/API/lang/swift/printdecl/TestSwiftTypeLookup.py

@@ -56,6 +56,12 @@ def test_swift_type_lookup(self):
                 'func bar()',
                 'var b'])
 
+        # Regression test. Ensure "<could not resolve type>" is not output.
+        self.expect(
+            "type lookup String",
+            matching=False,
+            substrs=["<could not resolve type>"])
+
         # check that specifiers are honored
         # self.expect('type lookup class Cla1', substrs=['class Cla1 {'])
         # self.expect('type lookup struct Cla1', substrs=['class Cla1 {'], matching=False, error=True)