Extended Description

I have a simple program that should show the problem. - with libc++ the stream is still good after closing and further operation. Since also the file content was not updated - at least the stream operation fails on the closed stream and should set either failbit or badbit to reflect the situation.

#include
#include

int main(int argc, const char * argv[])
{
std::fstream ofs("test.txt", std::ios::out | std::ios::trunc);
ofs << "Hello, World!\n";
ofs.close();
ofs << "Hello, World!\n";
std::cout << "good(): " << ofs.good()
<< " fail(): " << ofs.fail()
<< " bad(): " << ofs.bad()
<< " eof(): " << ofs.eof() << std::endl;
return 0;
}

// http://coliru.stacked-crooked.com/a/cfaeb32849c9cfad

With libc++ I get
good(): 1 fail(): 0 bad(): 0 eof(): 0

Expected (or with libstdc++):
good(): 0 fail(): 1 bad(): 1 eof(): 0

I have tested on OSX with Xcode 9.4.1
Apple LLVM version 9.1.0 (clang-902.0.39.2)

or on Linux:
clang version 3.8.0