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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - std::filesystem::create_directory and std::filesystem::create_directories have inconsistent error handling"
href="https://bugs.llvm.org/show_bug.cgi?id=41683">41683</a>
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<th>Summary</th>
<td>std::filesystem::create_directory and std::filesystem::create_directories have inconsistent error handling
</td>
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<th>Product</th>
<td>libc++
</td>
</tr>
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<th>Version</th>
<td>8.0
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>All Bugs
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<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ssh@pobox.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<p>
<div>
<pre>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 <a href="https://wandbox.org/permlink/Wa0Ie40k24rBwGmY">https://wandbox.org/permlink/Wa0Ie40k24rBwGmY</a>)
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 (<a href="https://cplusplus.github.io/LWG/issue2935">https://cplusplus.github.io/LWG/issue2935</a>) 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 <a href="https://github.com/cplusplus/draft/issues/2703">https://github.com/cplusplus/draft/issues/2703</a>).
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!</pre>
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