diff --git a/clang-tools-extra/clangd/IncludeFixer.cpp b/clang-tools-extra/clangd/IncludeFixer.cpp
--- a/clang-tools-extra/clangd/IncludeFixer.cpp
+++ b/clang-tools-extra/clangd/IncludeFixer.cpp
@@ -78,6 +78,7 @@
   case diag::err_sizeof_alignof_incomplete_or_sizeless_type:
   case diag::err_for_range_incomplete_type:
   case diag::err_func_def_incomplete_result:
+  case diag::err_field_incomplete_or_sizeless:
     // Incomplete type diagnostics should have a QualType argument for the
     // incomplete type.
     for (unsigned Idx = 0; Idx < Info.getNumArgs(); ++Idx) {
diff --git a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
--- a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
@@ -38,8 +38,9 @@
 using ::testing::Field;
 using ::testing::IsEmpty;
 using ::testing::Pair;
-using testing::SizeIs;
+using ::testing::SizeIs;
 using ::testing::UnorderedElementsAre;
+using testing::UnorderedElementsAreArray;
 
 ::testing::Matcher<const Diag &> WithFix(::testing::Matcher<Fix> FixMatcher) {
   return Field(&Diag::Fixes, ElementsAre(FixMatcher));
@@ -770,6 +771,10 @@
 }
 
 ns::X $return[[func]]() {}
+
+class T {
+  ns::X $field[[x]];
+};
   )cpp");
   auto TU = TestTU::withCode(Test.code());
   TU.ExtraArgs.push_back("-std=c++17");
@@ -779,57 +784,64 @@
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
-      UnorderedElementsAre(
-          AllOf(Diag(Test.range("nested"),
-                     "incomplete type 'ns::X' named in nested name specifier"),
-                DiagName("incomplete_nested_name_spec"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("base"), "base class has incomplete type"),
-                DiagName("incomplete_base_class"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("access"),
-                     "member access into incomplete type 'ns::X'"),
-                DiagName("incomplete_member_access"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(
-              Diag(Test.range("type"),
+      UnorderedElementsAreArray(
+          {AllOf(Diag(Test.range("nested"),
+                      "incomplete type 'ns::X' named in nested name specifier"),
+                 DiagName("incomplete_nested_name_spec"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("base"), "base class has incomplete type"),
+                 DiagName("incomplete_base_class"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("access"),
+                      "member access into incomplete type 'ns::X'"),
+                 DiagName("incomplete_member_access"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(
+               Diag(
+                   Test.range("type"),
                    "incomplete type 'ns::X' where a complete type is required"),
-              DiagName("incomplete_type"),
-              WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                          "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("incomplete"),
-                     "variable has incomplete type 'ns::X'"),
-                DiagName("typecheck_decl_incomplete_type"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(
-              Diag(Test.range("tag"), "incomplete definition of type 'ns::X'"),
-              DiagName("typecheck_incomplete_tag"),
-              WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                          "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(
-              Diag(Test.range("use"), "invalid use of incomplete type 'ns::X'"),
-              DiagName("invalid_incomplete_type_use"),
-              WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                          "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("sizeof"), "invalid application of 'sizeof' to "
-                                           "an incomplete type 'ns::X'"),
-                DiagName("sizeof_alignof_incomplete_or_sizeless_type"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("for"),
-                     "cannot use incomplete type 'ns::X' as a range"),
-                DiagName("for_range_incomplete_type"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X"))),
-          AllOf(Diag(Test.range("return"),
-                     "incomplete result type 'ns::X' in function definition"),
-                DiagName("func_def_incomplete_result"),
-                WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
-                            "Add include \"x.h\" for symbol ns::X")))));
+               DiagName("incomplete_type"),
+               WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                           "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("incomplete"),
+                      "variable has incomplete type 'ns::X'"),
+                 DiagName("typecheck_decl_incomplete_type"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(
+               Diag(Test.range("tag"), "incomplete definition of type 'ns::X'"),
+               DiagName("typecheck_incomplete_tag"),
+               WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                           "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("use"),
+                      "invalid use of incomplete type 'ns::X'"),
+                 DiagName("invalid_incomplete_type_use"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("sizeof"),
+                      "invalid application of 'sizeof' to "
+                      "an incomplete type 'ns::X'"),
+                 DiagName("sizeof_alignof_incomplete_or_sizeless_type"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("for"),
+                      "cannot use incomplete type 'ns::X' as a range"),
+                 DiagName("for_range_incomplete_type"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("return"),
+                      "incomplete result type 'ns::X' in function definition"),
+                 DiagName("func_def_incomplete_result"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X"))),
+           AllOf(Diag(Test.range("field"), "field has incomplete type 'ns::X'"),
+                 DiagName("field_incomplete_or_sizeless"),
+                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
+                             "Add include \"x.h\" for symbol ns::X")))}))
+      << Test.code();
 }
 
 TEST(IncludeFixerTest, NoSuggestIncludeWhenNoDefinitionInHeader) {