[libcap] Build error on arm-linux

[igorkofman]

Package: libcap:arm-linux -> 2.69#2

Host Environment

• Host: arm-linux
• Compiler: GNU 10.2.1
• vcpkg-tool version: 2999-12-31-unknownhash
  vcpkg-scripts version: 3f3d8b0 2023-12-12 (22 hours ago)

To Reproduce

vcpkg install
Failure logs

-- Using cached libpcap-2.69.tar.gz.
-- Cleaning sources at /home/igor/drawme/src/vcpkg/buildtrees/libcap/src/libpcap-2-fe0a022327.clean. Use --editable to skip cleaning for the packages you specify.
-- Extracting source /home/igor/drawme/src/vcpkg/downloads/libpcap-2.69.tar.gz
-- Using source at /home/igor/drawme/src/vcpkg/buildtrees/libcap/src/libpcap-2-fe0a022327.clean
-- Getting CMake variables for arm-linux-dbg
-- Getting CMake variables for arm-linux-rel
-- Configuring arm-linux-dbg
-- Configuring arm-linux-rel
-- Building arm-linux-dbg
CMake Error at scripts/cmake/vcpkg_execute_build_process.cmake:134 (message):
    Command failed: /usr/bin/make V=1 -j 5 -f Makefile.vcpkg all
    Working Directory: /home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/
    See logs for more information:
      /home/igor/drawme/src/vcpkg/buildtrees/libcap/build-arm-linux-dbg-out.log
      /home/igor/drawme/src/vcpkg/buildtrees/libcap/build-arm-linux-dbg-err.log

Call Stack (most recent call first):
  scripts/cmake/vcpkg_build_make.cmake:151 (vcpkg_execute_build_process)
  scripts/cmake/vcpkg_install_make.cmake:2 (vcpkg_build_make)
  ports/libcap/portfile.cmake:25 (vcpkg_install_make)
  scripts/ports.cmake:170 (include)

/home/igor/drawme/src/vcpkg/buildtrees/libcap/build-arm-linux-dbg-err.log

/bin/sh: 1: ./_makenames: not found
make[1]: *** [Makefile:82: cap_names.h] Error 127
make: *** [Makefile.vcpkg:16: libcap/cap_names.h] Error 2

/home/igor/drawme/src/vcpkg/buildtrees/libcap/build-arm-linux-dbg-out.log

/usr/bin/make -C libcap cap_names.h "AR=/usr/bin/arm-linux-gnueabihf-ar"     "BUILD_CC=touch a.out | touch conftest | true"     "CC=/usr/bin/arm-linux-gnueabihf-gcc"     "RANLIB=/usr/bin/arm-linux-gnueabihf-ranlib"     "lib=lib"     "prefix=/home/igor/drawme/src/vcpkg_installed/arm-linux/debug" SHARED=no
make[1]: Entering directory '/home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/libcap'
=> making cap_names.list.h from /home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/libcap/../libcap/include/uapi/linux/capability.h
grep -E '^#define\s+CAP_([^\s]+)\s+[0-9]+\s*$' include/uapi/linux/capability.h | sed -e 's/^#define\s\+/{"/' -e 's/\s*$/},/' -e 's/\s\+/",/' -e 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/' > cap_names.list.h
touch a.out | touch conftest | true -O2 -Dlinux -Wall -Wwrite-strings -Wpointer-arith -Wcast-qual -Wcast-align -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs -Winline -Wshadow -Wunreachable-code  -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I/home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/libcap/../libcap/include/uapi -I/home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/libcap/../libcap/include _makenames.c -o _makenames
./_makenames > cap_names.h
make[1]: Leaving directory '/home/igor/drawme/src/vcpkg/buildtrees/libcap/arm-linux-dbg/libcap'

Additional context

vcpkg.json

{
  "name": "your-project-name",
  "version-string": "0.1.0",
  "dependencies": [
    "boost-json",
    {
      "name": "google-cloud-cpp",
      "features": [
        "speech"
      ]
    },
    "curl",
    "sdl2",
    "sdl2-image",
    "sdl2-ttf"
  ]
}

[igorkofman]

"BUILD_CC=touch a.out | touch conftest | true" seems weird and predictably doesn't output anything useful

[dg0yt]

"BUILD_CC=touch a.out | touch conftest | true" seems weird and predictably doesn't output anything useful

This is intentional. Ports are not allow to build host binaries while building for another target triplet.
OTOH BUILD_CC shall be identical to CC (and working) when the target triplet is identical to the host triplet.

Based on this pattern, the port is designed to not need to build and run _makenames when the target triplet is different from the host triplet, by re-using cap_names.h from the host triplet. Now the question is why it doesn't work in your case.

• What is the host triplet?
• It the host triplet is different from arm-linux, does the vcpkg host libcap installation have the file?
• Do the logs indicate whether copying the file fails?

[trolgar]

This is a side effect of the change made to linux.cmake file in the scripts/toolchains folder. It now assumes that all arm or arm64 builds are cross-compile builds, even on arm or arm64 hosts. Adding the x86_64 check back fixes this issue.

Would adding a test for ARM, instead of x86_64, in both the arm and arm64 conditions work?

if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Linux" AND NOT CMAKE_HOST_SYSTEM_PROCESSOR MATCHES "^(arm|aarch64)")

[dg0yt]

Simple question again:
What is the host triplet?

[dg0yt]

"BUILD_CC=touch a.out | touch conftest | true" seems weird and predictably doesn't output anything useful

This is intentional. Ports are not allow to build host binaries while building for another target triplet. OTOH BUILD_CC shall be identical to CC (and working) when the target triplet is identical to the host triplet.

I notice that the last sentence doesn't match the actual behavior of vcpkg_configure_make. It just looks for --host instead:

vcpkg/scripts/cmake/vcpkg_configure_make.cmake

Lines 378 to 386 in 0e47c19

	if(NOT arg_BUILD_TRIPLET MATCHES "--host")
	z_vcpkg_append_to_configure_environment(configure_env CC_FOR_BUILD "${VCPKG_DETECTED_CMAKE_C_COMPILER}")
	z_vcpkg_append_to_configure_environment(configure_env CPP_FOR_BUILD "${VCPKG_DETECTED_CMAKE_C_COMPILER} -E")
	z_vcpkg_append_to_configure_environment(configure_env CXX_FOR_BUILD "${VCPKG_DETECTED_CMAKE_CXX_COMPILER}")
	else()
	z_vcpkg_append_to_configure_environment(configure_env CC_FOR_BUILD "touch a.out | touch conftest${VCPKG_HOST_EXECUTABLE_SUFFIX} | true")
	z_vcpkg_append_to_configure_environment(configure_env CPP_FOR_BUILD "touch a.out | touch conftest${VCPKG_HOST_EXECUTABLE_SUFFIX} | true")
	z_vcpkg_append_to_configure_environment(configure_env CXX_FOR_BUILD "touch a.out | touch conftest${VCPKG_HOST_EXECUTABLE_SUFFIX} | true")
	endif()

#35084 only made this visible. I see the proper fix in updating vcpkg_configure_make:
(also) use the host tool as <tool>_FOR_BUILD when not VCPKG_CROSSCOMPILING. CC @Neumann-A

[dg0yt]

As immediate workaround, you can try replacing CC_FOR_BUILD with CC in ports/libcap/configure.

[trolgar]

For me, both the host triplet and target triplet are arm64-linux. I am compiling on a Raspberry PI 4 running Ubuntu 22.04.

[dg0yt]

Thanks - Can you also try the proposed workaround?

[trolgar]

It does work. That is what I originally did to get by. But with the current linux.cmake, the compiler choice is aarch64-linux-gnu-gcc and not cc. In my case that is fine because they point to the same compiler. But would there be some instances that would not be the case?

[dg0yt]

But with the current linux.cmake, the compiler choice is aarch64-linux-gnu-gcc and not cc. In my case that is fine because they point to the same compiler. But would there be some instances that would not be the case?

There might be the situation that the prefixed variant doesn't exist for the native cc.