[Sema] A flexible array member must not be the only named member

We didn't correctly detect situations where a flexible array member was
the only named member in a record.

This fixes PR28407.

llvm-svn: 274477

2 files changed, 8 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 0567a59f8da..7797ff1efc4 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -13952,14 +13952,12 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
                      : getLangOpts().CPlusPlus
                            ? diag::ext_flexible_array_union_gnu
                            : diag::err_flexible_array_union;
-      else if (Fields.size() == 1)
+      else if (NumNamedMembers < 1)
         DiagID = getLangOpts().MicrosoftExt
                      ? diag::ext_flexible_array_empty_aggregate_ms
                      : getLangOpts().CPlusPlus
                            ? diag::ext_flexible_array_empty_aggregate_gnu
-                           : NumNamedMembers < 1
-                                 ? diag::err_flexible_array_empty_aggregate
-                                 : 0;
+                           : diag::err_flexible_array_empty_aggregate;
 
       if (DiagID)
         Diag(FD->getLocation(), DiagID) << FD->getDeclName()
diff --git a/clang/test/Sema/MicrosoftExtensions.c b/clang/test/Sema/MicrosoftExtensions.c
index cdef5dc309d..62e5285970a 100644
--- a/clang/test/Sema/MicrosoftExtensions.c
+++ b/clang/test/Sema/MicrosoftExtensions.c
@@ -6,6 +6,12 @@ struct A
    int a[];  /* expected-warning {{flexible array member 'a' in otherwise empty struct is a Microsoft extension}} */
 };
 
+struct PR28407
+{
+  int : 1;
+  int a[]; /* expected-warning {{flexible array member 'a' in otherwise empty struct is a Microsoft extension}} */
+};
+
 struct C {
    int l;
    union {