Bug - Leading Whitespace On Stream In

[jnhyatt]

There is an issue where leading whitespace in an input stream buffer causes a path to be invalid.

To reproduce:

fs::path path;
std::istringstream ss("line text.txt");
std::string directive;
ss >> directive >> path;

std::ifstream fileIn(path); // tries to open " text.txt" (leading space, nonexistent file)
assert (fileIn); // assertion fails when using ghc::filesystem

See a compiling example here. This was tested using MSVC 16.4.5 and g++ 9.1.0. In both configurations, std::filesystem behaves as expected (run std-fs in the root directory) where ghc::filesystem returns a path with a leading space and fails to properly parse when handed to std::ifstream (run alt-fs in the root directory).

The fix simply streams in the first character when testing for a quote character. This causes the operation to respect the current skipws flag. Using std::basic_istream::get() will ignore the skipws flag and simply read in the first character (if there is leading whitespace, a whitespace character). If the skipws flag is set in the istream, both std::filesystem and ghc::filesystem read in the whitespace character and fail the assertion.

[gulrak]

Nice catch, thank you!