[PATCH BZ#19239] Improve deprecation warnings

[Zack Weinberg <zackw at panix dot com>]

By using __glibc_macro_warning instead of __attribute_deprecated__,
we get the deprecation warnings whenever the macros are expanded, not
just when they compile to a function call.  This is important for
unintentional uses like the test case in #19239.  It's also simpler,
because __REDIRECT is no longer required.

__SYSMACROS_DM(1) is tricksy: by writing the full text of the
deprecation message directly inside the call to __SYSMACROS_DM1,
we prevent all those bare identifiers from being macro-expanded
(because they're the immediate subject of stringification) while
still being able to substitute ‘symbol’.  (Neither _Pragma itself
nor #pragma GCC warning permits string-literal concatenation.)

OK?

zw
-- 

	BZ#19239
        * misc/sys/cdefs.h (__glibc_macro_warning):
        Use #pragma GCC warning for clang >=3.5 as well.
        * misc/sys/sysmacros.h: Use __glibc_macro_warning instead of
        __attribute_deprecated_msg__ to diagnose deprecated definitions via
        sys/types.h.

diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 50e00e6..49b0956 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -474,7 +474,7 @@

 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
    intended for use in preprocessor macros.  */
-#if __GNUC_PREREQ (4,8)
+#if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 # define __glibc_macro_warning1(message) _Pragma (#message)
 # define __glibc_macro_warning(message) \
   __glibc_macro_warning1 (GCC warning message)
diff --git a/misc/sys/sysmacros.h b/misc/sys/sysmacros.h
index 086e9af..5600672 100644
--- a/misc/sys/sysmacros.h
+++ b/misc/sys/sysmacros.h
@@ -40,54 +40,39 @@
 #include <bits/types.h>
 #include <bits/sysmacros.h>

-/* The extra "\n " moves gcc's [-Wdeprecated-declarations] annotation
-   onto the next line.  */
-#define __SYSMACROS_DEPRECATION_MSG(symbol)				     \
-  "\n  In the GNU C Library, `" #symbol "' is defined by
<sys/sysmacros.h>." \
-  "\n  For historical compatibility, it is currently defined by"	     \
-  "\n  <sys/types.h> as well, but we plan to remove this soon."		     \
-  "\n  To use `" #symbol "', include <sys/sysmacros.h> directly."	     \
-  "\n  If you did not intend to use a system-defined macro `" #symbol
"',"   \
-  "\n  you should #undef it after including <sys/types.h>."		     \
-  "\n "
+/* Caution: if you change the whitespace in and around this macro,
+   it may malfunction.  Newline placement is tuned for GCC 6.  */
+#define __SYSMACROS_DM(symbol) __SYSMACROS_DM1 \
+ (In the GNU C Library, #symbol is defined\n\
+  by <sys/sysmacros.h>. For historical compatibility, it is\n\
+  currently defined by <sys/types.h> as well, but we plan to\n\
+  remove this soon.  To use #symbol, include <sys/sysmacros.h>\n\
+  directly.  If you did not intend to use a system-defined macro\n\
+  #symbol, you should undefine it after including <sys/types.h>.)
+
+/* This macro is variadic because the deprecation message above
+   contains commas.  */
+#define __SYSMACROS_DM1(...) __glibc_macro_warning (#__VA_ARGS__)

 #define __SYSMACROS_DECL_TEMPL(rtype, name, proto)			     \
   extern rtype gnu_dev_##name proto __THROW __attribute_const__;

-#define __SYSMACROS_FST_DECL_TEMPL(rtype, name, proto)			     \
-  extern rtype __REDIRECT_NTH (__##name##_from_sys_types, proto,	     \
-			       gnu_dev_##name)				     \
-       __attribute_const__						     \
-       __attribute_deprecated_msg__ (__SYSMACROS_DEPRECATION_MSG (name));
-
 #define __SYSMACROS_IMPL_TEMPL(rtype, name, proto)			     \
   __extension__ __extern_inline __attribute_const__ rtype		     \
   __NTH (gnu_dev_##name proto)

-#define __SYSMACROS_FST_IMPL_TEMPL(rtype, name, proto)			     \
-  __extension__ __extern_inline __attribute_const__ rtype		     \
-  __NTH (__##name##_from_sys_types proto)
-
 __BEGIN_DECLS

 __SYSMACROS_DECLARE_MAJOR (__SYSMACROS_DECL_TEMPL)
 __SYSMACROS_DECLARE_MINOR (__SYSMACROS_DECL_TEMPL)
 __SYSMACROS_DECLARE_MAKEDEV (__SYSMACROS_DECL_TEMPL)

-__SYSMACROS_DECLARE_MAJOR (__SYSMACROS_FST_DECL_TEMPL)
-__SYSMACROS_DECLARE_MINOR (__SYSMACROS_FST_DECL_TEMPL)
-__SYSMACROS_DECLARE_MAKEDEV (__SYSMACROS_FST_DECL_TEMPL)
-
 #ifdef __USE_EXTERN_INLINES

 __SYSMACROS_DEFINE_MAJOR (__SYSMACROS_IMPL_TEMPL)
 __SYSMACROS_DEFINE_MINOR (__SYSMACROS_IMPL_TEMPL)
 __SYSMACROS_DEFINE_MAKEDEV (__SYSMACROS_IMPL_TEMPL)

-__SYSMACROS_DEFINE_MAJOR (__SYSMACROS_FST_IMPL_TEMPL)
-__SYSMACROS_DEFINE_MINOR (__SYSMACROS_FST_IMPL_TEMPL)
-__SYSMACROS_DEFINE_MAKEDEV (__SYSMACROS_FST_IMPL_TEMPL)
-
 #endif

 __END_DECLS
@@ -96,9 +81,7 @@ __END_DECLS

 #ifndef __SYSMACROS_NEED_IMPLEMENTATION
 # undef __SYSMACROS_DECL_TEMPL
-# undef __SYSMACROS_FST_DECL_TEMPL
 # undef __SYSMACROS_IMPL_TEMPL
-# undef __SYSMACROS_FST_IMPL_TEMPL
 # undef __SYSMACROS_DECLARE_MAJOR
 # undef __SYSMACROS_DECLARE_MINOR
 # undef __SYSMACROS_DECLARE_MAKEDEV
@@ -108,9 +91,9 @@ __END_DECLS
 #endif

 #ifdef __SYSMACROS_DEPRECATED_INCLUSION
-# define major(dev) __major_from_sys_types (dev)
-# define minor(dev) __minor_from_sys_types (dev)
-# define makedev(maj, min) __makedev_from_sys_types (maj, min)
+# define major(dev) __SYSMACROS_DM (major) gnu_dev_major (dev)
+# define minor(dev) __SYSMACROS_DM (minor) gnu_dev_minor (dev)
+# define makedev(maj, min) __SYSMACROS_DM (makedev) gnu_dev_makedev
(maj, min)
 #else
 # define major(dev) gnu_dev_major (dev)
 # define minor(dev) gnu_dev_minor (dev)