[libcxx] Remove static inline and make use of _LIBCPP_HIDE_FROM_ABI in __support headers

[brad]

Summary

After some feedback in https://reviews.llvm.org/D122861, I am wondering if this makes sense for the respective headers for AIX, z/OS, Solaris and musl libc.

[Mordante]

Thanks for the followup patch! SGTM, but I like to see the feedback of the maintainers of the affected systems before approving.

[brad]

In D124227#3470042, @Mordante wrote:

but I like to see the feedback of the maintainers of the affected systems before approving.

Oh for sure. That's what I want.

[ldionne]

Looking at this and D122861 again, it strikes me that perhaps the goal was for these to be valid when compiling as C. However, I think that might be a non-goal since one should simply not have libc++ in the header search paths when compiling as C.

So this LGTM, but pinging vendors for awareness. I suggest you ship this if nobody objects within a week or so, just to avoid stalling.

[daltenty]

This change seems ok in principal, but these functions are extern 'C", so now that they're no longer internal linkage they'll provide the same symbol as the real thing. Adding such functions with linkable POSIX reserved names into user program seems like we are asking for trouble. Can we get these moved into some kind of namespace or at least with some kind of double underscore prefix?

(As a side note, _LIBCPP_HIDE_FROM_ABI doesn't exactly work as intend on AIX yet either, as we don't have complete visibility support in clang at the moment. That's something we're actively working on though)

[brad]

Any guidance as to how I should proceed?

[daltenty]

Any guidance as to how I should proceed?

I'm ok if this goes ahead as is from the AIX perspective (sorry didn't mean to stall this if it's waiting from my earlier comment). I can take a todo to revisit my earlier suggestion if we run into problems.

libcxx/include/__support/ibm/gettod_zos.h

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _LIBCPP_SUPPORT_IBM_GETTOD_ZOS_H
 #define _LIBCPP_SUPPORT_IBM_GETTOD_ZOS_H
 
 #include <time.h>
 
-static inline int gettimeofdayMonotonic(struct timespec64* Output) {
+inline _LIBCPP_HIDE_FROM_ABI int
+gettimeofdayMonotonic(struct timespec64* Output) {
 
   // The POSIX gettimeofday() function is not available on z/OS. Therefore,
   // we will call stcke and other hardware instructions in implement equivalent.
   // Note that nanoseconds alone will overflow when reaching new epoch in 2042.
 
   struct _t {
     uint64_t Hi;
     uint64_t Lo;

libcxx/include/__support/ibm/xlocale.h

private:
   locale_t __stored = (locale_t)0;
   locale_t __cloc = (locale_t)0;
 };
 
 } // namespace
 
 // The following are not POSIX routines.  These are quick-and-dirty hacks
 // to make things pretend to work
-static inline
-long long strtoll_l(const char *__nptr, char **__endptr,
-    int __base, locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI long long
+strtoll_l(const char *__nptr, char **__endptr, int __base, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtoll(__nptr, __endptr, __base);
+  return ::strtoll(__nptr, __endptr, __base);
 }
 
-static inline
-long strtol_l(const char *__nptr, char **__endptr,
-    int __base, locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI long
+strtol_l(const char *__nptr, char **__endptr, int __base, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtol(__nptr, __endptr, __base);
+  return ::strtol(__nptr, __endptr, __base);
 }
 
-static inline
-double strtod_l(const char *__nptr, char **__endptr,
-    locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI double
+strtod_l(const char *__nptr, char **__endptr, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtod(__nptr, __endptr);
+  return ::strtod(__nptr, __endptr);
 }
 
-static inline
-float strtof_l(const char *__nptr, char **__endptr,
-    locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI float
+strtof_l(const char *__nptr, char **__endptr, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtof(__nptr, __endptr);
+  return ::strtof(__nptr, __endptr);
 }
 
-static inline
-long double strtold_l(const char *__nptr, char **__endptr,
-    locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI long double
+strtold_l(const char *__nptr, char **__endptr, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtold(__nptr, __endptr);
+  return ::strtold(__nptr, __endptr);
 }
 
-static inline
-unsigned long long strtoull_l(const char *__nptr, char **__endptr,
-    int __base, locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI unsigned long long
+strtoull_l(const char *__nptr, char **__endptr, int __base, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtoull(__nptr, __endptr, __base);
+  return ::strtoull(__nptr, __endptr, __base);
 }
 
-static inline
-unsigned long strtoul_l(const char *__nptr, char **__endptr,
-    int __base, locale_t locale) {
+inline _LIBCPP_HIDE_FROM_ABI unsigned long
+strtoul_l(const char *__nptr, char **__endptr, int __base, locale_t locale) {
   __setAndRestore __newloc(locale);
-  return strtoul(__nptr, __endptr, __base);
+  return ::strtoul(__nptr, __endptr, __base);
 }
 
-static inline
-int vasprintf(char **strp, const char *fmt, va_list ap) {
+inline _LIBCPP_HIDE_FROM_ABI int
+vasprintf(char **strp, const char *fmt, va_list ap) {
   const size_t buff_size = 256;
   if ((*strp = (char *)malloc(buff_size)) == NULL) {
     return -1;
   }
 
   va_list ap_copy;
   // va_copy may not be provided by the C library in C++ 03 mode.
 #if defined(_LIBCPP_CXX03_LANG) && __has_builtin(__builtin_va_copy)

libcxx/include/__support/musl/xlocale.h

 
 #include <cstdlib>
 #include <cwchar>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-static inline long long strtoll_l(const char *nptr, char **endptr, int base,
-                                  locale_t) {
-  return strtoll(nptr, endptr, base);
+inline _LIBCPP_HIDE_FROM_ABI long long
+strtoll_l(const char *nptr, char **endptr, int base, locale_t) {
+  return ::strtoll(nptr, endptr, base);
 }
 
-static inline unsigned long long strtoull_l(const char *nptr, char **endptr,
-                                            int base, locale_t) {
-  return strtoull(nptr, endptr, base);
+inline _LIBCPP_HIDE_FROM_ABI unsigned long long
+strtoull_l(const char *nptr, char **endptr, int base, locale_t) {
+  return ::strtoull(nptr, endptr, base);
 }
 
-static inline long long wcstoll_l(const wchar_t *nptr, wchar_t **endptr,
-                                  int base, locale_t) {
-  return wcstoll(nptr, endptr, base);
+inline _LIBCPP_HIDE_FROM_ABI long long
+wcstoll_l(const wchar_t *nptr, wchar_t **endptr, int base, locale_t) {
+  return ::wcstoll(nptr, endptr, base);
 }
 
-static inline unsigned long long wcstoull_l(const wchar_t *nptr,
-                                            wchar_t **endptr, int base,
-                                            locale_t) {
-  return wcstoull(nptr, endptr, base);
+inline _LIBCPP_HIDE_FROM_ABI long long
+wcstoull_l(const wchar_t *nptr, wchar_t **endptr, int base, locale_t) {
+  return ::wcstoull(nptr, endptr, base);
 }
 
-static inline long double wcstold_l(const wchar_t *nptr, wchar_t **endptr,
-                                    locale_t) {
-  return wcstold(nptr, endptr);
+inline _LIBCPP_HIDE_FROM_ABI long double
+wcstold_l(const wchar_t *nptr, wchar_t **endptr, locale_t) {
+  return ::wcstold(nptr, endptr);
 }
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // _LIBCPP_SUPPORT_MUSL_XLOCALE_H

libcxx/include/__support/solaris/xlocale.h

 
 int toupper_l(int __c, locale_t __l);
 int tolower_l(int __c, locale_t __l);
 
 struct lconv *localeconv(void);
 struct lconv *localeconv_l(locale_t __l);
 
 // FIXME: These are quick-and-dirty hacks to make things pretend to work
-static inline
-long long strtoll_l(const char *__nptr, char **__endptr,
-    int __base, locale_t __loc) {
-  return strtoll(__nptr, __endptr, __base);
-}
-static inline
-long strtol_l(const char *__nptr, char **__endptr,
-    int __base, locale_t __loc) {
-  return strtol(__nptr, __endptr, __base);
-}
-static inline
-unsigned long long strtoull_l(const char *__nptr, char **__endptr,
-    int __base, locale_t __loc) {
-  return strtoull(__nptr, __endptr, __base);
-}
-static inline
-unsigned long strtoul_l(const char *__nptr, char **__endptr,
-    int __base, locale_t __loc) {
-  return strtoul(__nptr, __endptr, __base);
-}
-static inline
-float strtof_l(const char *__nptr, char **__endptr,
-    locale_t __loc) {
-  return strtof(__nptr, __endptr);
-}
-static inline
-double strtod_l(const char *__nptr, char **__endptr,
-    locale_t __loc) {
-  return strtod(__nptr, __endptr);
-}
-static inline
-long double strtold_l(const char *__nptr, char **__endptr,
-    locale_t __loc) {
-  return strtold(__nptr, __endptr);
+inline _LIBCPP_HIDE_FROM_ABI long long
+strtoll_l(const char *__nptr, char **__endptr, int __base, locale_t __loc) {
+  return ::strtoll(__nptr, __endptr, __base);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI long
+strtol_l(const char *__nptr, char **__endptr, int __base, locale_t __loc) {
+  return ::strtol(__nptr, __endptr, __base);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI unsigned long long
+strtoull_l(const char *__nptr, char **__endptr, int __base, locale_t __loc) 
+  return ::strtoull(__nptr, __endptr, __base);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI unsigned long
+strtoul_l(const char *__nptr, char **__endptr, int __base, locale_t __loc) {
+  return ::strtoul(__nptr, __endptr, __base);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI float
+strtof_l(const char *__nptr, char **__endptr, locale_t __loc) {
+  return ::strtof(__nptr, __endptr);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI double
+strtod_l(const char *__nptr, char **__endptr, locale_t __loc) {
+  return ::strtod(__nptr, __endptr);
+}
+
+inline _LIBCPP_HIDE_FROM_ABI long double
+strtold_l(const char *__nptr, char **__endptr, locale_t __loc) {
+  return ::strtold(__nptr, __endptr);
 }
 
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif