[illumos-gate merge]HEADmaster

commit f4d2cf74960df993f48d42d323f16867fc6b9bdf
    15253 14993 broke test-runner -l option
commit fb2301db8e408458b542c1f5fa07b5b8a3a95395
    15258 libsmb: tautological-pointer-compare
commit abd30308264aa9ca2b1c71565b841fc94256d07b
    15211 smbtorture failures in smb2.delete-on-close-perms.READONLY
commit 0663b557d8c7575927b005cab08d9f19c8b98c25
    15200 libdladm: error: '&&' within '||'
commit bf7adeeaefd6f9806398f446e4b87af240a6770e
    15199 libdladm: unused label
commit 92f549282aaface1e6f92329085e28edcf24054f
    15207 libfmd_agent: memory leak in fmd_agent_nvl_ioctl
commit 7b5987898994d86cd20e00dbf8c305dfbfbb8bea
    15135 stdalign.h is very C11-y, but perhaps disrespectful of C++

1 files changed, 18 insertions, 5 deletions

diff --git a/usr/src/head/stdalign.h b/usr/src/head/stdalign.h
index 2577a8de92..15160d660e 100644
--- a/usr/src/head/stdalign.h
+++ b/usr/src/head/stdalign.h
@@ -11,30 +11,43 @@
 
 /*
  * Copyright 2016 Joyent, Inc.
+ * Copyright 2022 Oxide Computer Company
  */
 
 #ifndef _STDALIGN_H
 #define	_STDALIGN_H
 
 /*
- * ISO/IEC C11 stdalign.h
+ * ISO/IEC C11 stdalign.h. This header is meant to provide definitions for the
+ * alignas and alignof 'keywords' into the underlying compiler-understood value.
+ * In addition, there are two macros that are meant to define that this process
+ * has happened. C++11 added alignas/alignof as keywords and including this
+ * header is meant to cause us to still have the _is_defined macros, but not
+ * define this overall.
+ *
+ * Unlike other cases we don't use any symbol guards here (other than C++) and
+ * just allow the implementation to either have _Alignas and _Alignof or not
+ * have it and lead to a compiler error for the user. The main justification of
+ * this is that this header is only defined in C11 (and newer). It's not defined
+ * in other standards and just as if you include a non-standard header, in this
+ * case we don't try to stop that (same as if you included something like
+ * libdevinfo.h).
  */
-#include <sys/feature_tests.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#if !defined(_STRICT_SYMBOLS) || defined(_STDC_C11)
+#ifndef	__cplusplus
 
 #define	alignas	_Alignas
 #define	alignof	_Alignof
 
+#endif	/* !__cplusplus */
+
 #define	__alignas_is_defined	1
 #define	__alignof_is_defined	1
 
-#endif	/* !_STRICT_SYMBOLS || _STDC_C11 */
-
 #ifdef __cplusplus
 }
 #endif