John;
It’s usually a good thing to read the release notes for each version of Xcode. The Xcode 10 release notes directly mention the issue you are facing:
Building with libstdc++ was deprecated with Xcode 8 and is not supported in Xcode 10
when targeting iOS. C++ projects must now migrate to libc++ and are recommended to set
a deployment target of macOS 10.9 or later, or iOS 7 or later. Besides changing the C++
Standard Library build setting, developers should audit hard-coded linker flags and target
dependencies to remove references to libstdc++ (including -lstdc++, -lstdc++.6.0.9,
libstdc++.6.0.9.tbd, and libstdc++.6.0.9.dylib). Project dependencies such as static
archives that were built against libstdc++ will also need to be rebuilt against libc++.
(40885260)
Libgcc is obsoleted. Xcode 10 can no longer build apps with deployment targets of macOS
10.4 and 10.5. (42818150, 38035243)
It looks like they really want you to change libraries to use libc++.
Jack
I discovered one thing that is a bug in Xcode. In the section Apple Clang - Language - C++, if you set the C++ Standard Library to the option libstdc++ (GNU C++ Standard Library), it generates the -std=libstdc++. When it fails to find it, it generates the erroneous warning. Anyway, it looks as though the issue is that the C++ library that I rely on is built with the GNU C++ Standard Library in mind, and that is not present on my machine. I assume that it disappeared at some point in the past, possibly between Xcode 9.2 (which was the last version I was using) and Xcode 10.0. Is there a way to get it back? John Alex Zavatone via Groups.Io wrote on 20/9/18 21:24: Did you change your linked library to the new C++ one?
On Sep 20, 2018, at 2:32 AM, John Brownie <john_brownie@...> wrote:
After a hiatus of some months, I'm back to programming, and just got Xcode 10 installed. When I go to build, I get all kinds of changes suggested. I make some, but then I get stuck some that I cannot work out. My project is a mixture of Objective-C, Objective-C++, C++, and a little Swift (in a separate target).
When I start to build the first target, clang gives the the warning:
warning: include path for stdlibc++ headers not found; pass '-std=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
OK, so I add a compiler flag as suggested, and I get the following warnings:
error: invalid value 'libc++' in '-std=libc++'
note: use 'c++98' or 'c++03' for 'ISO C++ 1998 with amendments' standard
note: use 'gnu++98' or 'gnu++03' for 'ISO C++ 1998 with amendments and GNU extensions' standard
note: use 'c++11' for 'ISO C++ 2011 with amendments' standard
note: use 'gnu++11' for 'ISO C++ 2011 with amendments and GNU extensions' standard
note: use 'c++14' for 'ISO C++ 2014 with amendments' standard
note: use 'gnu++14' for 'ISO C++ 2014 with amendments and GNU extensions' standard
note: use 'c++17' for 'ISO C++ 2017 with amendments' standard
note: use 'gnu++17' for 'ISO C++ 2017 with amendments and GNU extensions' standard
note: use 'c++2a' for 'Working draft for ISO C++ 2020' standard
note: use 'gnu++2a' for 'Working draft for ISO C++ 2020 with GNU extensions' standard
Using one of those (c++11), brings me back to the first warning. And then the compiler can't find the standard library headers (e.g. <algorithm>), anyway.
One of the suggested changes was "Update C++ Standard Library", so I reverted to pre-changes and didn't make that change, which got me to the second set of warnings.
Anyone have an idea how to break out of this cycle?
John
--
John Brownie
Mussau-Emira language, New Ireland Province, Papua New Guinea
Kouvola, Finland
-- John Brownie Mussau-Emira language, New Ireland Province, Papua New Guinea Kouvola, Finland
|
