Clang 10 fails to link C++ application with CMake on macOS 10.12

Question

I have a Jenkins build server running macOS 10.12.

I am compiling a C++ application using the latest Clang 10 (not AppleClang) with CMake 3.17.

The error I get is:

The C++ compiler

"/Users/XXX/llvm/bin/clang++"

is not able to compile a simple test program.

It fails with the following output:

ld: unknown option: -platform_version
clang-10: error: linker failed with exit code 1

This works fine with Clang 9 on the same server and Clang 10 works fine on macOS 10.15 with all other build tools and source files the same (Jenkins runs a clean build each time). It seems to be the combination of Clang 10 and macOS 10.12. Has anything changed between Clang 9 and Clang 10 that would cause this?

I'm invoking CMake like so:

cmake -DCMAKE_OSX_SYSROOT="${macos_sdk}" \
      -DCMAKE_C_COMPILER="${llvm_bin}/clang" \
      -DCMAKE_CXX_COMPILER="${llvm_bin}/clang++" \
      -DCMAKE_OSX_ARCHITECTURES=${architectures} \
      -DCMAKE_BUILD_TYPE=${make_build_type} ..

@Richard Barber `lld` from the LLVM 10 bin diectory where Clang 10 resides. Passed to CMake via `-DCMAKE_LINKER="${llvm_bin}/lld"` where `llvm_bin` is where LLVM 10 is located on my build server — keith, Mar 30 '20 at 18:18
Also what version ld. I suspect you are using a pre-520 binary. — Richard Barber, Mar 30 '20 at 18:25
@Richard Barber - `ld -v` gives `ld64-305 ... LTO support using: LLVM version 9.0.0 (clang-900.0.39.2) ...` — keith, Mar 30 '20 at 18:29
@Richard Barber, using `DCMAKE_CXX_LINK_EXECUTABLE` does not seem to fix the issue - based on this line of thinking it might be that CMake is ignoring the linker I want to use? — keith, Mar 30 '20 at 18:53
Since cmake uses the compiler to call `ld` make sure you specify the compiler (by passing variables to cmake). I usually say `CC=/path/to/clang CXX=/path/to/clang++ cmake …` etc. — Richard Barber, Mar 30 '20 at 19:35
@Richard Barber, I already am specifying the compiler - I've updated the information. — keith, Mar 30 '20 at 19:50
@Richard Barber, i have resolved this issue by manually specifying the linker version - I suspect this is a bug in Clang. — keith, Mar 31 '20 at 19:34

keith · Accepted Answer · 2020-04-01T18:57:29.283

7

Passing the linker version to Clang via -mlinker-version=305 resolved the issue.

For CMake this can be done like so:

-DCMAKE_CXX_FLAGS="-mlinker-version=305"

Can't help but feel this is a bug.

The linker verison can be obtained via ld -v on macOS 10.12 where the problem occurs.

A handy bash function to get the ld version for passing to Clang:

#!/bin/bash

function get_ld_version() {
  local info=$( ld -v 2>&1 > /dev/null )

  echo "${info}" | perl -wne '/.ld64-(.*?)[^0-9]/ and print "$1\n"'
}

edited Apr 01 '20 at 18:57

answered Mar 31 '20 at 19:31

keith

5,122
3
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50

Have you considered adding this as an answer to your [other question](https://stackoverflow.com/questions/60944732/using-fuse-ld-lld-with-clang-on-macos)? I think the current accepted answer there is somewhat misleading. – fakedad Jan 03 '21 at 00:35
@fakedad, the accepted answer to [my other question](https://stackoverflow.com/questions/60944732/using-fuse-ld-lld-with-clang-on-macos) does answer the other question. My other question was the wrong question to have asked to solve the problem here. – keith Jan 03 '21 at 17:10

score 2 · Answer 2 · answered May 01 '20 at 11:14

Just in case someone is using CMAKE with CLion IDE which tests both C and C++ compilers, adding -DCMAKE_CXX_FLAGS="-mlinker-version=405"isn't enough you also need to add "-DCMAKE_C_FLAGS="-mlinker-version=405", of course as what @keith mentioned you should use your own linker version

Clang 10 fails to link C++ application with CMake on macOS 10.12

2 Answers2

Linked