testsuite: std_list handling for { target c++26 }

As with c++23, we want to run { target c++26 } tests even though it isn't
part of the default std_list.

C++17 with Concepts TS is no longer an interesting target configuration.

And bump the impcx target to use C++26 mode instead of 23.

gcc/testsuite/ChangeLog:

	* lib/g++-dg.exp (g++-dg-runtest): Update for C++26.

diff --git a/gcc/testsuite/lib/g++-dg.exp b/gcc/testsuite/lib/g++-dg.exp
index 08185a8987e00e3ffa198b6e0337ed70ff983ef9..046d63170c8c85419fea40a3c58579feb9aaed71 100644 (file)
--- a/gcc/testsuite/lib/g++-dg.exp
+++ b/gcc/testsuite/lib/g++-dg.exp
@@ -58,17 +58,17 @@ proc g++-dg-runtest { testcases flags default-extra-flags } {
                # single test.  This should be updated or commented
                # out whenever the default std_list is updated or newer
                # C++ effective target is added.
-               if [search_for $test "{ dg-do * { target c++23 } }"] {
-                   set std_list { 23 }
+               if [search_for $test "\{ dg-do * \{ target c++23"] {
+                   set std_list { 23 26 }
+               } elseif [search_for $test "\{ dg-do * \{ target c++26"] {
+                   set std_list { 26 }
                } else {
                    set std_list { 98 14 17 20 }
                }
            }
            set option_list { }
            foreach x $std_list {
-               # Handle "concepts" as C++17 plus Concepts TS.
-               if { $x eq "concepts" } then { set x "17 -fconcepts"
-               } elseif { $x eq "impcx" } then { set x "23 -fimplicit-constexpr" }
+               if { $x eq "impcx" } then { set x "26 -fimplicit-constexpr" }
                lappend option_list "${std_prefix}$x"
            }
        } else {