testsuite: Fix up g++.dg/cpp2a/concepts-lambda3.C [PR108972]

On Fri, Mar 10, 2023 at 01:49:38PM -0500, Jason Merrill via Gcc-patches wrote:
> gcc/testsuite/ChangeLog:
>
>       * g++.dg/cpp2a/concepts-lambda3.C: Run at lower std levels,
>       but expect errors.

I'm seeing
+UNRESOLVED: g++.dg/cpp2a/concepts-lambda3.C  -std=c++11 compilation failed to produce executable
+UNRESOLVED: g++.dg/cpp2a/concepts-lambda3.C  -std=c++14 compilation failed to produce executable
+UNRESOLVED: g++.dg/cpp2a/concepts-lambda3.C  -std=c++17 compilation failed to produce executable
+UNRESOLVED: g++.dg/cpp2a/concepts-lambda3.C  -std=c++98 compilation failed to produce executable
with this change, and if I test with
GXX_TESTSUITE_STDS=98,11,14,17,20,2b make check-g++ -k RUNTESTFLAGS="--target_board=unix\{-m32,-m64,-m64/-fconcepts\} dg.exp=concepts-lambda3.C"
I see even FAILs for the -fconcepts case, so apparently even -std=c++17
-fconcepts isn't enough to make it compile without errors.

The following patch will expect errors for all of c++17_down and will
make the test dg-do compile for that case too, such that the UNRESOLVED
stuff is gone.

2023-03-14  Jakub Jelinek  <jakub@redhat.com>

	PR c++/108972
	PR testsuite/109129
	* g++.dg/cpp2a/concepts-lambda3.C: Use dg-do run only for c++20,
	for c++17_down dg-do compile.  Expect dg-excess-errors for c++17_down
	rather than ! concepts.

1 files changed, 3 insertions, 2 deletions

diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
index b18e6b6..7a8eea6 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
@@ -1,5 +1,6 @@
-// { dg-do run }
-// { dg-excess-errors "" { target { ! concepts } } } (PR108972)
+// { dg-do run { target c++20 } }
+// { dg-do compile { target c++17_down } }
+// { dg-excess-errors "" { target { c++17_down } } } (PR108972)
 
 template<typename T>
 concept C1 = __is_same_as(T, int)