Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".
Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:
In utils/libcxx/test/config.py add:
self.cxx.compile_flags += ['-ffreestanding']
Run the tests and they all fail.
Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).
Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.
The former was done with The Magic Of Sed.
The later was done with a (not quite correct but decent) clang tool:
https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed
This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.
Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.
<rdar://problem/47754795>
Reviewers: ldionne, mclow.lists, EricWF
Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits
Differential Revision: https://reviews.llvm.org/D57624
llvm-svn: 353086
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351648
The clang assertion causing these tests failing with sanitizer is fixed
in r295794. All the bots running libcxx tests should be upgraded and
running the compiler with the fix.
llvm-svn: 296385
Summary:
This patch fixes http://llvm.org/PR31938. The description below is copy/pasted from the bug:
The standard says:
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT>>
class basic_string {
using value_type = typename traits::char_type;
// ...
basic_string(const charT* s, const Allocator& a = Allocator());
};
libc++ actually chooses to declare the constructor as
basic_string(const value_type* s, const Allocator& a = Allocator());
The implicit deduction guides from class template argument deduction make what was previously an implementation detail visible:
std::basic_string s = "foo"; // error, can't deduce charT.
The constructor in question is in the libc++ DSO, but fortunately it looks like fixing this will not result in an ABI break.
@rsmith How does this look? I did more than just the constructors mentioned in the PR, but IDK how far to take it.
Reviewers: mclow.lists, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits, rsmith
Differential Revision: https://reviews.llvm.org/D29863
llvm-svn: 295393
JF Bastien