[PATCH] c++: Remove superflous assert [PR104403]

[Jakub Jelinek via Gcc-patches]

Hi!

I've added the assert because start_decl diagnoses such vars for C++20 and
earlier:
  if (current_function_decl && VAR_P (decl)
      && DECL_DECLARED_CONSTEXPR_P (current_function_decl)
      && cxx_dialect < cxx23)
but as can be seen, we cam trigger the assert in older standards e.g. during
non-manifestly constant evaluation.  Rather than refining the assert that
DECL_EXPRs for such vars don't appear for C++20 and older if they are inside
of functions declared constexpr this patch just removes the assert, the
code rejects encountering those vars in constant expressions anyway.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2022-02-08  Jakub Jelinek  <ja...@redhat.com>

        PR c++/104403
        * constexpr.cc (cxx_eval_constant_expression): Don't assert DECL_EXPRs
        of TREE_STATIC vars may only appear in -std=c++23.

        * g++.dg/cpp0x/lambda/lambda-104403.C: New test.

--- gcc/cp/constexpr.cc.jj      2022-02-06 11:16:22.353814431 +0100
+++ gcc/cp/constexpr.cc 2022-02-07 11:38:59.131165171 +0100
@@ -6652,7 +6652,6 @@ cxx_eval_constant_expression (const cons
            /* Allow __FUNCTION__ etc.  */
            && !DECL_ARTIFICIAL (r))
          {
-           gcc_assert (cxx_dialect >= cxx23);
            if (!ctx->quiet)
              {
                if (CP_DECL_THREAD_LOCAL_P (r))
--- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C.jj        2022-02-07 
11:40:32.760847269 +0100
+++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C   2022-02-07 
11:40:06.109223079 +0100
@@ -0,0 +1,8 @@
+// PR c++/104403
+// { dg-do compile { target c++11 } }
+
+int
+main ()
+{
+  []{ switch (0) { case 0: static int value; return &value; } };
+}

        Jakub