fix bernmm compilation

/opt/conda/envs/sage-dev/x86_64-conda-linux-gnu/include/c++/12.3.0/bits/stl_tree.h:772:15: error: static assertion failed: comparison object must be invocable as const
  772 |               is_invocable_v<const _Compare&, const _Key&, const _Key&>,
  /opt/conda/envs/sage-dev/x86_64-conda-linux-gnu/include/c++/12.3.0/bits/stl_tree.h:772:15: note: 'std::is_invocable_v<const bernmm::Item_cmp&, bernmm::Item* const&, bernmm::Item* const&>' evaluates to false

Author: tobiasdiez

src/sage/rings/bernmm/bern_rat.cpp

@@ -87,7 +87,7 @@ struct Item
 */
 struct Item_cmp
 {
-   bool operator()(const Item* x, const Item* y)
+   bool operator()(const Item* x, const Item* y) const
    {
       return mpz_cmp(x->modulus, y->modulus) < 0;
    }
@@ -331,9 +331,9 @@ void bern_rat(mpq_t res, long k, int num_threads)
 #ifdef USE_THREADS
    for (long i = 0; i < num_threads - 1; i++)
       pthread_join(threads[i], NULL);
-#endif
 
    pthread_attr_destroy (&attr);
+#endif
 
    // reconstruct B_k as a rational number
    Item* item = *(state.items.begin());

src/sage/rings/meson.build

@@ -136,7 +136,7 @@ foreach name, pyx : extension_data
 endforeach
 
 extension_data_cpp = {
-    'bernmm': files('bernmm.pyx', 'bernmm/bern_modp.cpp', 'bernmm/bern_modp_util.cpp'),#, 'bernmm/bern_rat.cpp'), - TODO: Compilation error
+    'bernmm': files('bernmm.pyx', 'bernmm/bern_modp.cpp', 'bernmm/bern_modp_util.cpp', 'bernmm/bern_rat.cpp'),
     'bernoulli_mod_p': files('bernoulli_mod_p.pyx'),
     'fraction_field_FpT': files('fraction_field_FpT.pyx'),
     'rational': files('rational.pyx'),
@@ -147,6 +147,7 @@ foreach name, pyx : extension_data_cpp
         sources: pyx,
         subdir: 'sage/rings',
         install: true,
+        cpp_args: ['-DUSE_THREADS=1','-DTHREAD_STACK_SIZE=4096'],
         override_options : ['cython_language=cpp'],
         include_directories: [inc_arb, inc_cpython, inc_ext, inc_flint, inc_gsl, inc_ntl, inc_rings, inc_rings_finite],
         dependencies: [py_dep, cypari2, cysignals, flint, gmp, gmpy2, gsl, m, mpc, mpfi, mpfr, ntl, pari, pthread],