[musl] [C23 feature tests 0/4] Needed by other changes in C23

[musl] [C23 feature tests 0/4] Needed by other changes in C23

[Jens Gustedt]

C23 introduces new attribute syntax and uses some of the attributes in
the header specification of some functions. If musl is not compiled in
C23 mode (which it will be for some time) we have to emulate or ignore
these attributes with some macro tricks.

Other features include support for new integer types, some of them
mandatory such as _BitInt types. musl itself doesn't use these
features for the compilation of the library itself, for example all
functionality for 128 bit types will be emulated.  But feature test
will be needed on the application side to detect full support of
[u]int128_t types such that musl and compilers that support the types
can work together.

Jens Gustedt (4):
  C23: provide fallbacks for the use of C attributes
  C23: add a feature test for the [u]int128_t
  Add a feature test for the _BitInt types.
  C23: add an internal interface for the new unsequenced attribute

 include/features.h | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

-- 
2.34.1

[musl] [C23 feature tests 1/4] C23: provide fallbacks for the use of C attributes

[Jens Gustedt]

---
 include/features.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/features.h b/include/features.h
index 85cfb72a..8e1d84e3 100644
--- a/include/features.h
+++ b/include/features.h
@@ -35,6 +35,26 @@
 #define _Noreturn
 #endif
 
+#ifdef __has_c_attribute
+# if __has_c_attribute(__noreturn__)
+#  define __noreturn [[__noreturn__]]
+# endif
+# if __has_c_attribute(__deprecated__)
+#  define __deprecated [[__deprecated__]]
+# endif
+#endif
+
+#ifndef __noreturn
+# define __noreturn _Noreturn
+#endif
+#ifndef __deprecated
+# if defined(__GNUC__)
+#  define __deprecated __attribute__((__deprecated__))
+# else
+#  define __deprecated
+# endif
+#endif
+
 #define __REDIR(x,y) __typeof__(x) x __asm__(#y)
 
 #endif
-- 
2.34.1

[musl] [C23 feature tests 2/4] C23: add a feature test for the [u]int128_t

[Jens Gustedt]

---
 include/features.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/features.h b/include/features.h
index 8e1d84e3..9d0d3724 100644
--- a/include/features.h
+++ b/include/features.h
@@ -57,4 +57,11 @@
 
 #define __REDIR(x,y) __typeof__(x) x __asm__(#y)
 
+// If the platform supports the 128 integer type and has _BitInt(N)
+// support where N large enough (all C23 compiler should have the
+// latter)
+#if __SIZEOF_INT128__ && (__BITINT_MAXWIDTH__ >= 128)
+#define __has_int128_t 1
+#endif
+
 #endif
-- 
2.34.1

[musl] [C23 feature tests 3/4] Add a feature test for the _BitInt types.

[Jens Gustedt]

This test is not needed for the configuration of musl itself, but only
for the interfaces that are offered through headers.
---
 include/features.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/features.h b/include/features.h
index 9d0d3724..46eca334 100644
--- a/include/features.h
+++ b/include/features.h
@@ -57,10 +57,14 @@
 
 #define __REDIR(x,y) __typeof__(x) x __asm__(#y)
 
-// If the platform supports the 128 integer type and has _BitInt(N)
-// support where N large enough (all C23 compiler should have the
-// latter)
-#if __SIZEOF_INT128__ && (__BITINT_MAXWIDTH__ >= 128)
+// If the platform supports the _BitInt(128) types (all C23 compiler
+// should have that)
+#if __BITINT_MAXWIDTH__ >= 128 || BITINT_MAXWIDTH >= 128
+#define __has_bitint128 1
+#endif
+
+// If the platform supports the 128 integer type and has _BitInt(128)
+#if __SIZEOF_INT128__ && __has_bitint128
 #define __has_int128_t 1
 #endif
 
-- 
2.34.1

[musl] [C23 feature tests 4/4] C23: add an internal interface for the new unsequenced attribute

[Jens Gustedt]

---
 include/features.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/features.h b/include/features.h
index 46eca334..adc41c04 100644
--- a/include/features.h
+++ b/include/features.h
@@ -42,6 +42,9 @@
 # if __has_c_attribute(__deprecated__)
 #  define __deprecated [[__deprecated__]]
 # endif
+# if __has_c_attribute(__unsequenced__)
+#  define __unsequenced [[__unsequenced__]]
+# endif
 #endif
 
 #ifndef __noreturn
@@ -54,6 +57,13 @@
 #  define __deprecated
 # endif
 #endif
+#ifndef __unsequenced
+# if defined(__GNUC__)
+#  define __unsequenced __attribute__((__const__))
+# else
+#  define __unsequenced
+# endif
+#endif
 
 #define __REDIR(x,y) __typeof__(x) x __asm__(#y)
 
-- 
2.34.1