path::operator / does not remove redundant separators

[neo_in_matrix@…]

The following code produces path3 as \abc
def\, which is not expected.

filesystem::path path1("\\abc\\");
filesystem::path path2("\\def\\");
filesystem::path path3 = path1 / path2;

Though the OS level API can handle duplicate path seps correctly, but it is not considered good practice to return path strings like this.

[neo_in_matrix@…]

BTW, I have #define BOOST_FILESYSTEM_VERSION 3 so that I am using the newer version 3 of filesystem.hpp.

[neo_in_matrix@…]

Yeah... my first message is garbled by this bug system.

Let's say the code is like this:

filesystem::path path1("\\abc\\");
filesystem::path path2("\\xyz\\");
filesystem::path path3 = path1 / path2;
//path3 will be \abc\\xyz\, which has redundant path seps.

[Beman Dawes]

See ​http://cplusplus.github.io/filesystem-ts/working-draft.html#path-appends

The ISO C++ filesystem TS says:

Appends path::preferred_separator to pathname unless:

• an added separator would be redundant, or
• would change a relative path to an absolute path [Note: An empty path is relative. — end note], or
• p.empty(), or
• *p.native().cbegin() is a directory separator.

Then appends p.native() to pathname.

Boost.Filesystem follows the TS here. The TS does not add a separator if it would be redundant, but if native() ends with a separator and the append argument begins with a separator, both are retained.

You are free to report this to the C++ committee as defect, and if they decide to change the spec then Boost.Filesystem will follow their lead. But I'm not aware of any reason for adding a gratuitous difference between Boost and other implementation.

Thanks for your interest in Boost.Filesystem,

--Beman

PS: Test case added to verify the library works as expected per your test case.