From: Jonathan Wakely <jwakely@redhat.com>
Date: Sat, 26 Oct 2024 20:24:58 +0000 (+0100)
Subject: libstdc++: Fix std::vector<bool>::emplace to forward parameter
X-Git-Tag: basepoints/gcc-16~4845
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1c844be5202f4be446f165d9a7625eb7ec4c5b4;p=thirdparty%2Fgcc.git

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 --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));
+}