Only initialize the streams cout/wcout/cerr/wcerr etc once, rather than any time Init::Init is called. Fixes PR#43300

llvm-svn: 371864

2 files changed, 49 insertions, 2 deletions

diff --git a/libcxx/src/iostream.cpp b/libcxx/src/iostream.cpp
index 0a5d6e8d226..ad1920abc65 100644
--- a/libcxx/src/iostream.cpp
+++ b/libcxx/src/iostream.cpp
@@ -97,7 +97,13 @@ static void force_locale_initialization() {
 #endif
 }
 
-ios_base::Init::Init()
+class DoIOSInit {
+public:
+	DoIOSInit();
+	~DoIOSInit();
+};
+
+DoIOSInit::DoIOSInit()
 {
     force_locale_initialization();
 
@@ -126,7 +132,7 @@ ios_base::Init::Init()
 #endif
 }
 
-ios_base::Init::~Init()
+DoIOSInit::~DoIOSInit()
 {
 #ifndef _LIBCPP_HAS_NO_STDOUT
     ostream* cout_ptr = reinterpret_cast<ostream*>(cout);
@@ -141,4 +147,13 @@ ios_base::Init::~Init()
     wclog_ptr->flush();
 }
 
+ios_base::Init::Init()
+{
+    static DoIOSInit init_the_streams; // gets initialized once
+}
+
+ios_base::Init::~Init()
+{
+}
+
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/ios_Init.multiple.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/ios_Init.multiple.pass.cpp
new file mode 100644
index 00000000000..37b4de9def5
--- /dev/null
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/ios_Init.multiple.pass.cpp
@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <iostream>
+#include <cassert>
+
+#include "test_macros.h"
+
+// Test to make sure that the streams only get initialized once
+// Taken from https://bugs.llvm.org/show_bug.cgi?id=43300
+
+int main(int, char**)
+{
+
+    std::cout << "Hello!";
+    std::ios_base::fmtflags stock_flags = std::cout.flags();
+
+    std::cout << std::boolalpha << true;
+    std::ios_base::fmtflags ba_flags = std::cout.flags();
+    assert(stock_flags != ba_flags);
+
+    std::ios_base::Init init_streams;
+    std::ios_base::fmtflags after_init = std::cout.flags();
+    assert(after_init == ba_flags);
+
+    return 0;
+}