Check if the C standard for this C version is C23.
That is, check whether the C version is C23, with or without GCC extensions.
Function:
(defun version-std-c23p (version) (declare (xargs :guard (versionp version))) (or (version-case version :c23) (version-case version :c23+gcc)))
Theorem:
(defthm booleanp-of-version-std-c23p (b* ((yes/no (version-std-c23p version))) (booleanp yes/no)) :rule-classes :rewrite)
Theorem:
(defthm version-std-c23p-of-version-fix-version (equal (version-std-c23p (version-fix version)) (version-std-c23p version)))
Theorem:
(defthm version-std-c23p-version-equiv-congruence-on-version (implies (version-equiv version version-equiv) (equal (version-std-c23p version) (version-std-c23p version-equiv))) :rule-classes :congruence)