Merge #6879: fix: compilation error with newer clang-20

b396f98 fix: compilation error with newer clang-20 (Konstantin Akimov)

Pull request description:

  ## Issue being fixed or feature implemented

  `hana` still uses spaces before literal operator, while newer clang enforces C++23 requirement

      In file included from ./evo/dmnstate.h:19:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/for_each.hpp:15:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/concept/foldable.hpp:19:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/fold_left.hpp:20:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/unpack.hpp:16:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/at.hpp:16:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/concept/iterable.hpp:20:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/drop_front.hpp:20:
      In file included from DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/integral_constant.hpp:13:
      DASH/depends/x86_64-pc-linux-gnu/include/boost/hana/bool.hpp:198:35: error: identifier '_c' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
        198 |         constexpr auto operator"" _c() {
            |                        ~~~~~~~~~~~^~
            |                        operator""_c

  ## What was done?
  Adds `-Wno-error=deprecated-literal-operator` for clang

  ## How Has This Been Tested?
  Build locally successfully

  ## Breaking Changes
  N/A

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone

ACKs for top commit:
  UdjinM6:
    utACK b396f98
  kwvg:
    utACK b396f98

Tree-SHA512: a30c0dbd113a64f13d48f448e15cca1271b5b33865ad2445ed49f4f65b1e47fd6d8ccdbdae30b1c43d2fcd01f1cceef8a89edc123cb447aa241055e5d2866289

Author: PastaPastaPasta

configure.ac

@@ -453,6 +453,15 @@ if test "$enable_werror" = "yes"; then
   fi
   ERROR_CXXFLAGS=$CXXFLAG_WERROR
 
+  dnl -Wdeprecated-literal-operator cause problems with clang 20. Do not treat these warnings as errors.
+  dnl TODO: remove it once we update hana
+  AX_CHECK_COMPILE_FLAG([-Wdeprecated-literal-operator], [NOWARN_CXXFLAGS="$NOWARN_CXXFLAGS -Wno-error=deprecated-literal-operator"], [], [$CXXFLAG_WERROR], [AC_LANG_SOURCE([
+    #if !defined(__clang__) || defined(__INTEL_COMPILER)
+      #error Non-clang compiler detected, not setting flag
+    #endif
+    int main(void) { return 0; }
+  ])])
+
   dnl -Wattributes cause problems with some versions of GCC. Do not treat these warnings as errors.
   AX_CHECK_COMPILE_FLAG([-Wattributes], [NOWARN_CXXFLAGS="$NOWARN_CXXFLAGS -Wno-error=attributes"], [], [$CXXFLAG_WERROR], [AC_LANG_SOURCE([
     #if defined(__clang__) || defined(__INTEL_COMPILER) || !defined(__GNUC__)