[gcc r15-4708] libstdc++: Fix std::vector::emplace to forward parameter

[Jonathan Wakely via Gcc-cvs]

https://gcc.gnu.org/g:f1c844be5202f4be446f165d9a7625eb7ec4c5b4

commit r15-4708-gf1c844be5202f4be446f165d9a7625eb7ec4c5b4
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Sat Oct 26 21:24:58 2024 +0100

    libstdc++: Fix std::vector<bool>::emplace to forward parameter
    
    If the parameter is not lvalue-convertible to bool then the current code
    will fail to compile. The parameter should be forwarded to restore the
    original value category.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/stl_bvector.h (emplace_back, emplace): Forward
            parameter pack to preserve value category.
            * testsuite/23_containers/vector/bool/emplace_rvalue.cc: New
            test.

Diff:
---
 libstdc++-v3/include/bits/stl_bvector.h            |  4 ++--
 .../23_containers/vector/bool/emplace_rvalue.cc    | 24 ++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/bits/stl_bvector.h 
b/libstdc++-v3/include/bits/stl_bvector.h
index 42261ac5915f..70f69b5b5b55 100644
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -1343,7 +1343,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 #endif
        emplace_back(_Args&&... __args)
        {
-         push_back(bool(__args...));
+         push_back(bool(std::forward<_Args>(__args)...));
 #if __cplusplus > 201402L
          return back();
 #endif
@@ -1353,7 +1353,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
        _GLIBCXX20_CONSTEXPR
        iterator
        emplace(const_iterator __pos, _Args&&... __args)
-       { return insert(__pos, bool(__args...)); }
+       { return insert(__pos, bool(std::forward<_Args>(__args)...)); }
 #endif
 
     protected:
diff --git a/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_rvalue.cc 
b/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_rvalue.cc
new file mode 100644
index 000000000000..5dea2426d602
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_rvalue.cc
@@ -0,0 +1,24 @@
+// { dg-do compile { target c++11 } }
+
+#include <vector>
+
+struct S
+{
+  explicit operator bool() &&;
+};
+
+void
+test_emplace_back()
+{
+  S s;
+  std::vector<bool> v;
+  v.emplace_back(std::move(s));
+}
+
+void
+test_emplace()
+{
+  S s;
+  std::vector<bool> v;
+  v.emplace(v.begin(), std::move(s));
+}