diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 10aa711eef5..f7d8a35888b 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2021-12-11  Bruno Larsen  <blarsen@redhat.com>
+
+	PR gdb/28480
+
+	Pushed by Joel Brobecker  <brobecker@adacore.com>
+	* valops.c (struct_field_searcher::update_result): Improve
+	ambiguous member detection.
+
 2021-11-03  Luis Machado  <luis.machado@linaro.org>
 
 	PR gdb/28355
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 54cfd221abb..725f348db9f 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2021-12-11  Bruno Larsen  <blarsen@redhat.com>
+
+	PR gdb/28480
+
+	Pushed by Joel Brobecker  <brobecker@adacore.com>
+	* gdb.cp/ambiguous.cc: Add code to permit ambiguous member testing.
+	* gdb.cp/ambiguous.exp: Add ambiguous member test.
+
 2021-10-22  Tom de Vries  <tdevries@suse.de>
 
 	PR tui/28483
diff --git a/gdb/testsuite/gdb.cp/ambiguous.cc b/gdb/testsuite/gdb.cp/ambiguous.cc
index a55686547f2..af2198dcfbc 100644
--- a/gdb/testsuite/gdb.cp/ambiguous.cc
+++ b/gdb/testsuite/gdb.cp/ambiguous.cc
@@ -1,3 +1,4 @@
+class empty { };
 
 class A1 {
 public:
@@ -17,6 +18,17 @@ public:
   int y;
 };
 
+#if !defined (__GNUC__) || __GNUC__ > 7
+# define NO_UNIQUE_ADDRESS [[no_unique_address]]
+#else
+# define NO_UNIQUE_ADDRESS
+#endif
+
+class A4 {
+public:
+    NO_UNIQUE_ADDRESS empty x;
+};
+
 class X : public A1, public A2 {
 public:
   int z;
@@ -77,6 +89,10 @@ public:
   int jva1v;
 };
 
+class JE : public A1, public A4 {
+public:
+};
+
 int main()
 {
   A1 a1;
@@ -92,6 +108,7 @@ int main()
   JVA1 jva1;
   JVA2 jva2;
   JVA1V jva1v;
+  JE je;
   
   int i;
 
@@ -173,5 +190,7 @@ int main()
   jva1v.i = 4;
   jva1v.jva1v = 5;
 
+  je.A1::x = 1;
+
   return 0; /* set breakpoint here */
 }
diff --git a/gdb/testsuite/gdb.cp/ambiguous.exp b/gdb/testsuite/gdb.cp/ambiguous.exp
index 008898c5818..1e63dc0c5dc 100644
--- a/gdb/testsuite/gdb.cp/ambiguous.exp
+++ b/gdb/testsuite/gdb.cp/ambiguous.exp
@@ -264,3 +264,13 @@ gdb_test "print (A1)(KV)jva1" " = \{x = 3, y = 4\}"
 # JVA1V is derived from A1; A1 is a virtual base indirectly
 # and also directly; must not report ambiguity when a JVA1V is cast to an A1.
 gdb_test "print (A1)jva1v" " = {x = 1, y = 2}"
+
+# C++20 introduced a way to have ambiguous fields with the same byte offset.
+# This class explicitly tests for that.
+# if this is tested with a compiler that can't handle [[no_unique_address]]
+# the code should still correctly identify the ambiguity because of
+# different byte offsets.
+test_ambiguous "je.x" "x" "JE" {
+    "'int A1::x' (JE -> A1)"
+    "'empty A4::x' (JE -> A4)"
+}
diff --git a/gdb/valops.c b/gdb/valops.c
index bd547923496..3769ab9630a 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1969,6 +1969,34 @@ struct_field_searcher::update_result (struct value *v, LONGEST boffset)
 	     space.  */
 	  if (m_fields.empty () || m_last_boffset != boffset)
 	    m_fields.push_back ({m_struct_path, v});
+	  else
+	    {
+	    /*Fields can occupy the same space and have the same name (be
+	      ambiguous).  This can happen when fields in two different base
+	      classes are marked [[no_unique_address]] and have the same name.
+	      The C++ standard says that such fields can only occupy the same
+	      space if they are of different type, but we don't rely on that in
+	      the following code. */
+	      bool ambiguous = false, insert = true;
+	      for (const found_field &field: m_fields)
+		{
+		  if(field.path.back () != m_struct_path.back ())
+		    {
+		    /* Same boffset points to members of different classes.
+		       We have found an ambiguity and should record it.  */
+		      ambiguous = true;
+		    }
+		  else
+		    {
+		    /* We don't need to insert this value again, because a
+		       non-ambiguous path already leads to it.  */
+		      insert = false;
+		      break;
+		    }
+		}
+	      if (ambiguous && insert)
+		m_fields.push_back ({m_struct_path, v});
+	    }
 	}
     }
 }