[PATCH] testsuite: fix allocator-opt1.C FAIL with old ABI

[Marek Polacek <polacek@redhat.com>]

Running
$ make check-g++ RUNTESTFLAGS='--target_board=unix\{-D_GLIBCXX_USE_CXX11_ABI=0,\} dg.exp=allocator-opt1.C'
yields:

FAIL: g++.dg/tree-ssa/allocator-opt1.C  -std=c++98  scan-tree-dump-times gimple "struct allocator D" 1
FAIL: g++.dg/tree-ssa/allocator-opt1.C  -std=c++14  scan-tree-dump-times gimple "struct allocator D" 1
FAIL: g++.dg/tree-ssa/allocator-opt1.C  -std=c++17  scan-tree-dump-times gimple "struct allocator D" 1
FAIL: g++.dg/tree-ssa/allocator-opt1.C  -std=c++20  scan-tree-dump-times gimple "struct allocator D" 1

		=== g++ Summary for unix/-D_GLIBCXX_USE_CXX11_ABI=0 ===

		=== g++ Summary for unix ===

because in the old ABI we get two "struct allocator D".  This patch
follows r14-658 although I'm not quite sure I follow the logic there.

Tested on x86_64-pc-linux-gnu, ok for trunk?

gcc/testsuite/ChangeLog:

	* g++.dg/tree-ssa/allocator-opt1.C: Force _GLIBCXX_USE_CXX11_ABI to 1.
---
 gcc/testsuite/g++.dg/tree-ssa/allocator-opt1.C | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gcc/testsuite/g++.dg/tree-ssa/allocator-opt1.C b/gcc/testsuite/g++.dg/tree-ssa/allocator-opt1.C
index e8394c7ad70..9f13eedb604 100644
--- a/gcc/testsuite/g++.dg/tree-ssa/allocator-opt1.C
+++ b/gcc/testsuite/g++.dg/tree-ssa/allocator-opt1.C
@@ -5,8 +5,18 @@
 // Currently the dump doesn't print the allocator template arg in this context.
 // { dg-final { scan-tree-dump-times "struct allocator D" 1 "gimple" } }
 
+// In the pre-C++11 ABI we get two allocator variables.
+#undef _GLIBCXX_USE_CXX11_ABI
+#define _GLIBCXX_USE_CXX11_ABI 1
+
+// When the library is not dual-ABI and defaults to old just compile
+// an empty TU
+#if _GLIBCXX_USE_CXX11_ABI
+
 #include <string>
 void f (const char *p)
 {
   std::string lst[] = { p, p, p, p };
 }
+
+#endif

base-commit: 2d7c95e31431a297060c94697af84f498abf97a2
-- 
2.41.0