[gcc r12-7112] c++: Remove superflous assert [PR104403]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:1755141a9ea0dddabb52776cddc4c9325eed27c6

commit r12-7112-g1755141a9ea0dddabb52776cddc4c9325eed27c6
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Feb 8 20:15:42 2022 +0100

    c++: Remove superflous assert [PR104403]
    
    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.
    
    2022-02-08  Jakub Jelinek  <jakub@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.

Diff:
---
 gcc/cp/constexpr.cc                               | 1 -
 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C | 8 ++++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index fd051172e00..9b8e0eced4b 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -6652,7 +6652,6 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
 	    /* Allow __FUNCTION__ etc.  */
 	    && !DECL_ARTIFICIAL (r))
 	  {
-	    gcc_assert (cxx_dialect >= cxx23);
 	    if (!ctx->quiet)
 	      {
 		if (CP_DECL_THREAD_LOCAL_P (r))
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C
new file mode 100644
index 00000000000..f231d3ea2c9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-104403.C
@@ -0,0 +1,8 @@
+// PR c++/104403
+// { dg-do compile { target c++11 } }
+
+int
+main ()
+{
+  []{ switch (0) { case 0: static int value; return &value; } };
+}