compiler: Define NO_RETURN for MSVC.

To prevent warnings such as "Not all control paths return a value",
we should define NO_RETURN for MSVC.

Currently for gcc, we add NO_RETURN at the end of function declaration.
But for MSVC, "__declspec(noreturn)" is needed at the beginning of function
declaration. So this commit moves NO_RETURN to the beginning of the function
declaration as it works with gcc and clang too.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

4 files changed, 31 insertions, 21 deletions

diff --git a/lib/compiler.h b/lib/compiler.h
index 5942c3029..629d09bf8 100644
--- a/lib/compiler.h
+++ b/lib/compiler.h
@@ -24,8 +24,17 @@
   #define __has_extension(x) 0
 #endif
 
+/* To make NO_RETURN portable across gcc/clang and MSVC, it should be
+ * added at the beginning of the function declaration. */
 #if __GNUC__ && !__CHECKER__
 #define NO_RETURN __attribute__((__noreturn__))
+#elif _MSC_VER
+#define NO_RETURN __declspec(noreturn)
+#else
+#define NO_RETURN
+#endif
+
+#if __GNUC__ && !__CHECKER__
 #define OVS_UNUSED __attribute__((__unused__))
 #define PRINTF_FORMAT(FMT, ARG1) __attribute__((__format__(printf, FMT, ARG1)))
 #define SCANF_FORMAT(FMT, ARG1) __attribute__((__format__(scanf, FMT, ARG1)))
@@ -37,7 +46,6 @@
 #define OVS_LIKELY(CONDITION) __builtin_expect(!!(CONDITION), 1)
 #define OVS_UNLIKELY(CONDITION) __builtin_expect(!!(CONDITION), 0)
 #else
-#define NO_RETURN
 #define OVS_UNUSED
 #define PRINTF_FORMAT(FMT, ARG1)
 #define SCANF_FORMAT(FMT, ARG1)
diff --git a/lib/stream-nossl.c b/lib/stream-nossl.c
index 23bc1fbdf..7dc5e0f7c 100644
--- a/lib/stream-nossl.c
+++ b/lib/stream-nossl.c
@@ -28,7 +28,7 @@ stream_ssl_is_configured(void)
     return false;
 }
 
-static void NO_RETURN
+NO_RETURN static void
 nossl_option(const char *detail)
 {
     VLOG_FATAL("%s specified but Open vSwitch was built without SSL support",
diff --git a/lib/util.h b/lib/util.h
index a2c6ee9c5..7da7aa8f0 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -74,7 +74,7 @@
     if (!OVS_LIKELY(CONDITION)) {                                       \
         ovs_assert_failure(SOURCE_LOCATOR, __func__, #CONDITION);       \
     }
-void ovs_assert_failure(const char *, const char *, const char *) NO_RETURN;
+NO_RETURN void ovs_assert_failure(const char *, const char *, const char *);
 
 /* Casts 'pointer' to 'type' and issues a compiler warning if the cast changes
  * anything other than an outermost "const" or "volatile" qualifier.
@@ -275,7 +275,7 @@ void set_subprogram_name(const char *format, ...) PRINTF_FORMAT(1, 2);
 const char *get_program_version(void);
 void ovs_print_version(uint8_t min_ofp, uint8_t max_ofp);
 
-void out_of_memory(void) NO_RETURN;
+NO_RETURN void out_of_memory(void);
 void *xmalloc(size_t) MALLOC_LIKE;
 void *xcalloc(size_t, size_t) MALLOC_LIKE;
 void *xzalloc(size_t) MALLOC_LIKE;
@@ -294,14 +294,14 @@ void free_cacheline(void *);
 void ovs_strlcpy(char *dst, const char *src, size_t size);
 void ovs_strzcpy(char *dst, const char *src, size_t size);
 
-void ovs_abort(int err_no, const char *format, ...)
-    PRINTF_FORMAT(2, 3) NO_RETURN;
-void ovs_abort_valist(int err_no, const char *format, va_list)
-    PRINTF_FORMAT(2, 0) NO_RETURN;
-void ovs_fatal(int err_no, const char *format, ...)
-    PRINTF_FORMAT(2, 3) NO_RETURN;
-void ovs_fatal_valist(int err_no, const char *format, va_list)
-    PRINTF_FORMAT(2, 0) NO_RETURN;
+NO_RETURN void ovs_abort(int err_no, const char *format, ...)
+    PRINTF_FORMAT(2, 3);
+NO_RETURN void ovs_abort_valist(int err_no, const char *format, va_list)
+    PRINTF_FORMAT(2, 0);
+NO_RETURN void ovs_fatal(int err_no, const char *format, ...)
+    PRINTF_FORMAT(2, 3);
+NO_RETURN void ovs_fatal_valist(int err_no, const char *format, va_list)
+    PRINTF_FORMAT(2, 0);
 void ovs_error(int err_no, const char *format, ...) PRINTF_FORMAT(2, 3);
 void ovs_error_valist(int err_no, const char *format, va_list)
     PRINTF_FORMAT(2, 0);
diff --git a/lib/vlog.h b/lib/vlog.h
index e5af21d61..974a30190 100644
--- a/lib/vlog.h
+++ b/lib/vlog.h
@@ -154,15 +154,17 @@ void vlog_valist(const struct vlog_module *, enum vlog_level,
                  const char *, va_list)
     PRINTF_FORMAT (3, 0);
 
-void vlog_fatal(const struct vlog_module *, const char *format, ...)
-    PRINTF_FORMAT (2, 3) NO_RETURN;
-void vlog_fatal_valist(const struct vlog_module *, const char *format, va_list)
-    PRINTF_FORMAT (2, 0) NO_RETURN;
-
-void vlog_abort(const struct vlog_module *, const char *format, ...)
-    PRINTF_FORMAT (2, 3) NO_RETURN;
-void vlog_abort_valist(const struct vlog_module *, const char *format, va_list)
-    PRINTF_FORMAT (2, 0) NO_RETURN;
+NO_RETURN void vlog_fatal(const struct vlog_module *, const char *format, ...)
+    PRINTF_FORMAT (2, 3);
+NO_RETURN void vlog_fatal_valist(const struct vlog_module *,
+                                 const char *format, va_list)
+    PRINTF_FORMAT (2, 0);
+
+NO_RETURN void vlog_abort(const struct vlog_module *, const char *format, ...)
+    PRINTF_FORMAT (2, 3);
+NO_RETURN void vlog_abort_valist(const struct vlog_module *,
+                                 const char *format, va_list)
+    PRINTF_FORMAT (2, 0);
 
 void vlog_rate_limit(const struct vlog_module *, enum vlog_level,
                      struct vlog_rate_limit *, const char *, ...)