https://bugs.llvm.org/show_bug.cgi?id=41683
Bug ID: 41683
Summary: std::filesystem::create_directory and
std::filesystem::create_directories have inconsistent
error handling
Product: libc++
Version: 8.0
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: All Bugs
Assignee: unassignedclangb...@nondot.org
Reporter: s...@pobox.com
CC: llvm-bugs@lists.llvm.org, mclow.li...@gmail.com
std::filesystem::create_directories and std::filesystem::create_directory
behave differently in case there is a regular file with the name of the
directory to create.
While implementing a std::filesystem compatible library myself I found this
while running my tests against the libc++ implementation:
std::filesystem::create_directories(p) throws filesystem_error wir "File
exists"
std::filesystem::create_directories(p,ec) sets the ec to a corresponding error
and returns false
std::filesystem::create_directory(p) reports false
std::filesystem::create_directory(p,ec) reports false and no error in ec
So for this code:
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
int main()
{
std::error_code ec;
std::cout << fs::create_directory("foo.txt", ec);
std::cout << (ec ? " error" : " no error") << std::endl;
ec.clear();
std::cout << fs::create_directories("foo.txt", ec);
std::cout << (ec ? " error" : " no error") << std::endl;
}
with an existing text file "foo.txt" the current result is:
0 no error
0 error
(see runnable example here https://wandbox.org/permlink/Wa0Ie40k24rBwGmY)
No matter which of these two behaviours is the correct one, they should behave
the same, in regard to this situation.
I know there is LWG issue 2935 (https://cplusplus.github.io/LWG/issue2935) that
requested a change to handling this situation as no error, but I'm with Nicolai
Josuttis, claiming this is not a good idea (see WG21 P1164R1, approved in Kona
and adopted with https://github.com/cplusplus/draft/issues/2703).
So in the end, all four operations should handle the case as an error.
(As additional information: GCCs libstdc++ had this behaviour swapped but
inconsistent too, and adopted the P1164R1 solution.)
Thanks for your work!
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