[gcc(refs/users/guojiufu/heads/personal-branch)] libstdc++: Compile PR93978 testcase with -Wall

[Jiu Fu Guo]

https://gcc.gnu.org/g:a57aa11191617754c8d43b3eb6a2576e970a0668

commit a57aa11191617754c8d43b3eb6a2576e970a0668
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat May 23 15:25:40 2020 -0400

    libstdc++: Compile PR93978 testcase with -Wall
    
    Now that the frontend issue PR c++/94038 is thoroughly fixed, the
    testcase for PR93978 no longer fails to compile with -O -Wall, so add
    -Wall to the testcase's compile flags to help ensure we don't regress
    here.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/93978
            * testsuite/std/ranges/adaptors/93978.cc: Add -Wall to
            dg-additional-options.  Avoid unused-but-set-variable warning.

Diff:
---
 libstdc++-v3/ChangeLog                              | 6 ++++++
 libstdc++-v3/testsuite/std/ranges/adaptors/93978.cc | 5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 167cb88b592..d899c69940d 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-23  Patrick Palka  <ppalka@redhat.com>
+
+	PR libstdc++/93978
+	* testsuite/std/ranges/adaptors/93978.cc: Add -Wall to
+	dg-additional-options.  Avoid unused-but-set-variable warning.
+
 2020-05-23  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/95289
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/93978.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/93978.cc
index a0152ec0532..82b82b0a5be 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/93978.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/93978.cc
@@ -16,7 +16,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-options "-std=gnu++2a" }
-// { dg-additional-options "-O" }
+// { dg-additional-options "-O -Wall" }
 // { dg-do compile { target c++2a } }
 
 #include <ranges>
@@ -25,11 +25,12 @@
 namespace ranges = std::ranges;
 namespace views = std::views;
 
-void
+auto
 test()
 {
   std::vector<std::string> x = {""};
   auto i = std::counted_iterator(x.begin(), 1);
   auto r = ranges::subrange{i, std::default_sentinel};
   auto v = r | views::join;
+  return v;
 }