Add ACE_FALLTHROUGH macro that adjusts to c++17 or earlier

6 files changed, 30 insertions, 10 deletions

diff --git a/ACE/ace/ACE.cpp b/ACE/ace/ACE.cpp
index fc820891251..7d48c80ee69 100644
--- a/ACE/ace/ACE.cpp
+++ b/ACE/ace/ACE.cpp
@@ -2197,11 +2197,11 @@ ACE::handle_ready (ACE_HANDLE handle,
     {
     case 0:  // Timer expired.
       errno = ETIME;
-      /* FALLTHRU */
+      ACE_FALLTHROUGH;
     case -1: // we got here directly - select() returned -1.
       return -1;
     case 1: // Handle has data.
-      /* FALLTHRU */
+      ACE_FALLTHROUGH;
     default: // default is case result > 0; return a
       // ACE_ASSERT (result == 1);
       return result;
@@ -2767,7 +2767,7 @@ ACE::fork (const ACE_TCHAR *program_name,
               return 0;
             case -1: // assumes all errnos are < 256
               ACE_OS::_exit (errno);
-              [[fallthrough]];    // gcc sees this as a fallthrough
+              ACE_FALLTHROUGH;    // gcc sees this as a fallthrough
             default:  // child terminates, orphaning grandchild
               ACE_OS::_exit (0);
             }
diff --git a/ACE/ace/CDR_Base.cpp b/ACE/ace/CDR_Base.cpp
index 0dda825809e..204bcc7ea30 100644
--- a/ACE/ace/CDR_Base.cpp
+++ b/ACE/ace/CDR_Base.cpp
@@ -239,12 +239,12 @@ ACE_CDR::swap_2_array (char const * orig, char* target, size_t n)
     ACE_CDR::swap_2 (orig, target);
     orig += 2;
     target += 2;
-    [[fallthrough]];
+    ACE_FALLTHROUGH;
   case 2:
     ACE_CDR::swap_2 (orig, target);
     orig += 2;
     target += 2;
-    [[fallthrough]];
+    ACE_FALLTHROUGH;
   case 1:
     ACE_CDR::swap_2 (orig, target);
   }
@@ -445,12 +445,12 @@ ACE_CDR::swap_4_array (char const * orig, char* target, size_t n)
     ACE_CDR::swap_4 (orig, target);
     orig += 4;
     target += 4;
-    [[fallthrough]];
+    ACE_FALLTHROUGH;
   case 2:
     ACE_CDR::swap_4 (orig, target);
     orig += 4;
     target += 4;
-    [[fallthrough]];
+    ACE_FALLTHROUGH;
   case 1:
     ACE_CDR::swap_4 (orig, target);
   }
diff --git a/ACE/ace/Name_Proxy.cpp b/ACE/ace/Name_Proxy.cpp
index 94cd1c9b584..3e4a676e4b0 100644
--- a/ACE/ace/Name_Proxy.cpp
+++ b/ACE/ace/Name_Proxy.cpp
@@ -151,14 +151,14 @@ ACE_Name_Proxy::recv_reply (ACE_Name_Request &reply)
     case -1:
       ACELIB_DEBUG ((LM_DEBUG,
                   ACE_TEXT ("****************** recv_reply returned -1\n")));
-      [[fallthrough]];
+      ACE_FALLTHROUGH;
     default:
       ACELIB_ERROR ((LM_ERROR,
                   ACE_TEXT ("%p got %d bytes, expected %d bytes\n"),
                   ACE_TEXT ("recv failed"),
                   n,
                   sizeof (ACE_UINT32)));
-      [[fallthrough]];
+      ACE_FALLTHROUGH;
     case 0:
       // We've shutdown unexpectedly
       return -1;
diff --git a/ACE/ace/OS_NS_unistd.cpp b/ACE/ace/OS_NS_unistd.cpp
index 4dc8ea1663d..b2ff267171a 100644
--- a/ACE/ace/OS_NS_unistd.cpp
+++ b/ACE/ace/OS_NS_unistd.cpp
@@ -350,7 +350,7 @@ ACE_OS::fork_exec (ACE_TCHAR *argv[])
               // If the execv fails, this child needs to exit.
               ACE_OS::exit (errno);
             }
-          [[ fallthrough ]];
+          ACE_FALLTHROUGH;
 #   endif /* ACE_HAS_WCHAR */
 
         default:
diff --git a/ACE/ace/config-g++-common.h b/ACE/ace/config-g++-common.h
index c01b73f70c6..be8714daf15 100644
--- a/ACE/ace/config-g++-common.h
+++ b/ACE/ace/config-g++-common.h
@@ -38,6 +38,15 @@
 # if __cplusplus > 199711L
 #  define ACE_HAS_CPP11
 # endif
+# if __cplusplus >= 201402L
+#  define ACE_HAS_CPP14
+# endif
+# if __cplusplus >= 201703L
+#  define ACE_HAS_CPP17
+# endif
+# if __cplusplus >= 202002L
+#  define ACE_HAS_CPP20
+# endif
 #endif
 
 #if (defined (i386) || defined (__i386__)) && !defined (ACE_SIZEOF_LONG_DOUBLE)
diff --git a/ACE/ace/config-macros.h b/ACE/ace/config-macros.h
index 22b544286ca..5f948b679ed 100644
--- a/ACE/ace/config-macros.h
+++ b/ACE/ace/config-macros.h
@@ -246,6 +246,17 @@
 # define ACE_NOTREACHED(a) a
 #endif /* ghs || ..... */
 
+
+// Compiler-specific configs can define ACE_FALLTHROUGH but if not,
+// and it's a C++17 or hgher compiler, use the defined mechanism.
+#if !defined ACE_FALLTHROUGH
+#  if defined ACE_HAS_CPP17
+#    define ACE_FALLTHROUGH [[fallthrough]]
+#  else
+#    define ACE_FALLTHROUGH
+#  endif /* ACE_HAS_CPP17 */
+#endif /* ACE_FALLTHROUGH */
+
 // ============================================================================
 // ACE_ALLOC_HOOK* macros
 //