function_ref test: Don't take reference of temporaries

When assigning the lambdas directly to a function_ref their lifetime is
limited to that of the expression. Store them on the stack first to
avoid the UB.

Fixes: QTBUG-104419
Change-Id: I3c85ac683b0bd7768b646dc9d0a1ed4dd173e6f3
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit 3d73aa660b5e1af5758ae7207ce1c05d7a0458e1)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 10 insertions, 5 deletions

diff --git a/tests/auto/corelib/global/qxp/function_ref/tst_qxp_function_ref.cpp b/tests/auto/corelib/global/qxp/function_ref/tst_qxp_function_ref.cpp
index be83e76f18..6264e6a5ae 100644
--- a/tests/auto/corelib/global/qxp/function_ref/tst_qxp_function_ref.cpp
+++ b/tests/auto/corelib/global/qxp/function_ref/tst_qxp_function_ref.cpp
@@ -221,16 +221,20 @@ void tst_qxp_function_ref::voidReturning()
 
     bool ok = false; // prevent lambdas from decaying to function pointers
     {
-        Fi fi = [&](int i) noexcept { return i + int(ok); };
+        auto lambda1 = [&](int i) noexcept { return i + int(ok); };
+        Fi fi = lambda1;
         fi(42);
-        Fv fv = [&]() noexcept { return int(ok); };
+        auto lambda2 = [&]() noexcept { return int(ok); };
+        Fv fv = lambda2;
         fv();
     }
 
     {
-        Fi fi = [&](int i) { return i + int(ok); };
+        auto lambda1 = [&](int i) { return i + int(ok); };
+        Fi fi = lambda1;
         fi(42);
-        Fv fv = [&]() { return int(ok); };
+        auto lambda2 = [&]() { return int(ok); };
+        Fv fv = lambda2;
         fv();
     }
 }
@@ -261,7 +265,8 @@ void tst_qxp_function_ref::ctad()
 
 #if 0 // no deduction guides for the non-function-pointer case, so no CTAD for lambdas
     {
-        qxp::function_ref f = [](int i) -> int { return i; };
+        auto lambda = [](int i) -> int { return i; };
+        qxp::function_ref f = lambda;
         static_assert(std::is_same_v<decltype(f),
                                      qxp::function_ref<int(int)>>);
     }