[bug] -rpath flag separator depends on build OS instead of host OS

[Erlkoenig90]

Environment Details (include every applicable attribute)

• Operating System+version: Linux Mint 20 Ulyana
• Compiler+version: clang version 10.0.0, Target: x86_64-apple-darwin19
• Conan version: 1.29.0 with PR Fix #7694, translate settings.os value 'Macos' to 'Darwin' for CMAKE_… #7695 applied
• Python version: 3.8.2

Steps to reproduce (Include if Applicable)

Install osxcross on Linux, create a profile with os=Macos and attempt to build glib with this PR applied, like this:

Logs (Executed commands with output) (Include/Attach if Applicable)

conan create . -pr:h x86_64-apple-darwin19-macosx-clang -pr:b default -o glib:with_elf=False

results in

[111/398] Linking target glib/libglib-2.0.0.dylib
FAILED: glib/libglib-2.0.0.dylib 
x86_64-apple-darwin19-clang  -o glib/libglib-2.0.0.dylib ... lots of stuff ... -Wl,-rpath=/home/niklas.guertler/.conan/data/pcre/8.41/_/_/package/ddd42dd21f101343926e8ee9dff966bdba84b078/lib /home/niklas.guertler/.conan/data/bzip2/1.0.8/_/_/package/d81a2c40ef3ca9d7c9333cd75ac1bcdef9183a77/lib/libbz2.a -Wl,-rpath=/home/niklas.guertler/.conan/data/bzip2/1.0.8/_/_/package/d81a2c40ef3ca9d7c9333cd75ac1bcdef9183a77/lib /home/niklas.guertler/.conan/data/zlib/1.2.11/_/_/package/099680e166ebfb4e7a7b9e0126a86c3d8bf1e7a7/lib/libz.a -Wl,-rpath=/home/niklas.guertler/.conan/data/zlib/1.2.11/_/_/package/099680e166ebfb4e7a7b9e0126a86c3d8bf1e7a7/lib -lgnuintl -liconv -liconv
ld: unknown option: -rpath=/home/niklas.guertler/.conan/data/pcre/8.41/_/_/package/ddd42dd21f101343926e8ee9dff966bdba84b078/lib
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)

The libpcre.pc file created by the pkg_config generator looks like this:

prefix=/home/niklas.guertler/.conan/data/pcre/8.41/_/_/package/ddd42dd21f101343926e8ee9dff966bdba84b078
libdir=${prefix}/lib
includedir=${prefix}/include

Name: pcre-libpcre
Description: Conan package: pcre-libpcre
Version: 8.41
Libs: -L${libdir} -lpcre  -Wl,-rpath="${libdir}"
Cflags: -I${includedir} -DPCRE_STATIC=1
Requires: bzip2 zlib

The ld64 linker used by Clang to (cross-)compile for Mac OS doesn't understand rpath flags with a = separator, which is why the rpath_flags function uses , instead of = when compiling on Mac OS. However, this does not work when cross-compiling on Linux for Mac OS, resulting in the malformed .pc files.

I would suggest changing the rpath_flags function to take the host (instead of build) OS as parameter and use that to determine the rpath_separator. I will submit a PR that does that.

[jgsogo]

Hi, I'm afraid this change will work for this scenario because "The ld64 linker used by Clang to (cross-)compile for Mac OS doesn't understand rpath flags with a = separator", but it might be broken for other scenarios where the linker used by other compilers to cross-compile expect those files in the format natural for the machine where the compiler is running (the build machine).

I'm not an expert on this topic, maybe @SSE4 has more sound opinion.

[Erlkoenig90]

Right, well it works for Cross-Compiling from Linux to Mac OS via osxcross and to Windows via MinGW32. I just noticed it's silly to pass os_host to rpath_flags because it's already in settings, so I reverted that. I added some logic to only set the -rpath to , when compiling for Mac OS from Linux or Mac OS via a GCC_LIKE-compiler (but left the other solution as a comment, so we can decide). That should fix this issue without influencing other use cases.