Fix GetDIE is outside of its CU error from .debug_names

Author: Jeffrey Tan

lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp

@@ -131,8 +131,12 @@ DebugNamesDWARFIndex::GetNonSkeletonUnit(const DebugNames::Entry &entry) const {
     unit_offset = entry.getLocalTUOffset();
   if (unit_offset) {
     if (DWARFUnit *cu = m_debug_info.GetUnitAtOffset(DIERef::Section::DebugInfo,
-                                                     *unit_offset))
-      return &cu->GetNonSkeletonUnit();
+                                                     *unit_offset)) {
+      DWARFUnit &ret = cu->GetNonSkeletonUnit();
+      if (ret.IsSkeletonUnit())
+        return nullptr;
+      return &ret;
+    }
   }
   return nullptr;
 }

lldb/test/Shell/SymbolFile/DWARF/dwo-miss-getdie-ouside-cu-error.c

@@ -0,0 +1,19 @@
+/// Check that LLDB does not emit "GetDIE for DIE {{0x[0-9a-f]+}} is outside of its CU"
+/// error message when user is searching for a matching symbol from .debug_names
+/// and fail to locate the corresponding .dwo file.
+
+/// -gsplit-dwarf is supported only on Linux.
+// REQUIRES: system-linux
+
+// RUN: %clang_host -g -gsplit-dwarf -gpubnames -gdwarf-5 %s -o main
+/// Remove the DWO file away from the expected location so that LLDB won't find the DWO next to the binary.
+// RUN: rm *.dwo
+// RUN: %lldb --no-lldbinit main \
+// RUN:   -o "b main" --batch 2>&1 | FileCheck %s
+
+// CHECK: warning: {{.*}}main unable to locate separate debug file (dwo, dwp). Debugging will be degraded.
+// CHECK-NOT: main GetDIE for DIE {{0x[0-9a-f]+}} is outside of its CU {{0x[0-9a-f]+}}
+
+int num = 5;
+
+int main(void) { return 0; }