[03/25] sys/types.h: Don’t define u_intN_t or register_t unless __USE_MISC.

Message ID 20190626174954.8009-4-zackw@panix.com
State Superseded

Commit Message

Zack Weinberg June 26, 2019, 5:49 p.m. UTC
  sys/types.h unconditionally defines u_int8_t, u_int16_t, u_int32_t,
u_int64_t, and register_t.  These are not part of any standard.  The
u_intXX_t types are superseded by C99’s uintXX_t types (defined in
stdint.h).  I’m not aware of a standardized exact equivalent of
register_t, but also I’ve never seen anyone use it for anything.
I could be persuaded to leave that one alone.

sys/types.h also unconditionally defines int8_t, int16_t, int32_t, and
int64_t, which are the same as the C99 exact-width signed types in
stdint.h.  POSIX doesn’t require these to appear in sys/types.h, so in
principle they ought to be brought under __USE_MISC also.  But, when I
tried that it broke about two dozen files just in our own source tree,
and POSIX doesn’t *forbid* sys/types.h to define these types, so I
think we should leave them alone.

	* posix/sys/types.h (u_int8_t, u_int16_t, u_int32_t, u_int64_t)
        (register_t): Move under #ifdef __USE_MISC.
        Consolidate adjacent #ifdef __USE_MISC blocks.
        * scripts/check_obsolete_constructs.py: Add register_t to the
        set of obsolete typedefs that our headers should not use
        (but sys/types.h may still define).
 NEWS                                 |  8 ++++++++
 posix/sys/types.h                    | 16 ++++++++--------
 scripts/check-obsolete-constructs.py |  1 +
 3 files changed, 17 insertions(+), 8 deletions(-)


diff --git a/NEWS b/NEWS
index 8a2fecef47..edf7739293 100644
--- a/NEWS
+++ b/NEWS
@@ -45,6 +45,14 @@  Deprecated and removed features, and other changes affecting compatibility:
 * The obsolete and never-implemented XSI STREAMS header files <stropts.h>
   and <sys/stropts.h> have been removed.
+* The typedefs u_int8_t, u_int16_t, u_int32_t, u_int64_t, and register_t
+  are no longer defined by <sys/types.h> in strict conformance modes.
+  These types were historically provided by <sys/types.h> on BSD systems,
+  but are not part of the POSIX specification for that header.  Applications
+  requiring fixed-width unsigned integer types should use the similarly
+  named uint8_t, uint16_t, etc. from <stdint.h>.  There is no standardized
+  replacement for register_t.
 * Support for the "inet6" option in /etc/resolv.conf and the RES_USE_INET6
   resolver flag (deprecated in glibc 2.25) have been removed.
diff --git a/posix/sys/types.h b/posix/sys/types.h
index 1bbd896ad4..7327904346 100644
--- a/posix/sys/types.h
+++ b/posix/sys/types.h
@@ -143,18 +143,20 @@  typedef __suseconds_t suseconds_t;
 #define	__need_size_t
 #include <stddef.h>
+/* POSIX does not require intN_t to be defined in this header, so
+   technically this ought to be under __USE_MISC, but it doesn't
+   forbid them to be defined here either, and much existing code
+   expects them to be defined here.  */
+#include <bits/stdint-intn.h>
 #ifdef __USE_MISC
 /* Old compatibility names for C types.  */
 typedef unsigned long int ulong;
 typedef unsigned short int ushort;
 typedef unsigned int uint;
-/* These size-specific names are used by some of the inet code.  */
-#include <bits/stdint-intn.h>
-/* These were defined by ISO C without the first `_'.  */
+/* These size-specific names are used by some of the inet code.
+   They were defined by ISO C without the first `_'.  */
 typedef __uint8_t u_int8_t;
 typedef __uint16_t u_int16_t;
 typedef __uint32_t u_int32_t;
@@ -167,8 +169,6 @@  typedef __register_t register_t;
    defined.  */
 #define __BIT_TYPES_DEFINED__	1
-#ifdef	__USE_MISC
 /* In BSD <sys/types.h> is expected to define BYTE_ORDER.  */
 # include <endian.h>
diff --git a/scripts/check-obsolete-constructs.py b/scripts/check-obsolete-constructs.py
index 89d21dea6e..4dc52761c5 100755
--- a/scripts/check-obsolete-constructs.py
+++ b/scripts/check-obsolete-constructs.py
@@ -254,6 +254,7 @@  class NoCheck(ConstructChecker):
 OBSOLETE_TYPE_RE_ = re.compile(r"""\A
   (   quad_t
+    | register_t
     | u(?: short | int | long
          | _(?: char | short | int(?:[0-9]+_t)? | long | quad_t )))
 \Z""", re.VERBOSE)