Update clang comments.

Author: evoskuil

include/bitcoin/system/have.hpp

@@ -204,9 +204,6 @@
     #endif
 #endif
 
-/// C++20: parenthesized initialization of aggregates requires clang16/xcode16.
-/// We don't have macro treatment for that, just ad-hoc HAVE_CLANG conditions.
-
 /// None on xcode.
 /// Requires link with -ltbb on gcc (v9).
 /// Experimental on clang (libcxx.llvm.org/Status/PSTL.html), requires:

include/bitcoin/system/literals.hpp

@@ -35,7 +35,7 @@ namespace libbitcoin {
 /// not be subject to regressions in other code, as a break here causes a large
 /// number of test and other failures. See tests for usage and detailed info.
 /// ---------------------------------------------------------------------------
-/// These should be consteval for safety, but waiting on clang++20 to catch up.
+/// These should be consteval for safety, but waiting on clang++ v17.
 
 // Functions are consteval where available (bogus warning).
 BC_PUSH_WARNING(USE_CONSTEXPR_FOR_FUNCTION)

test/allocator.cpp

@@ -26,10 +26,6 @@ BC_PUSH_WARNING(NO_UNGUARDED_POINTERS)
 BC_PUSH_WARNING(NO_DELETE_RAW_POINTER)
 BC_PUSH_WARNING(NO_UNCLEARED_OWNER_POINTER)
 
-// Clang is not yet C++20 compliant in terms of aggregate initialization.
-// See [reviews.llvm.org/D140327] for details. So vectors provide constructors.
-///////////////////////////////////////////////////////////////////////////////
-
 struct simple
 {
     simple(size_t arg={}) NOEXCEPT