macOS: libxml2 not found

[WuMingIT]

My first usage of meson in a long long time. I am trying to build libxkbcommon, either v1.3.1 or the latest v1.13.2, on an old macos 10.13. Meson latest v1.11.2.

libxml2 is installed:

$ ls /usr/lib/libxml2.*
/usr/lib/libxml2.2.dylib	/usr/lib/libxml2.dylib

$ ls /usr/include/libxml2/
libxml			module.modulemap

but not matter which version of libxkbcommon I try to build it always end as follows:

$ meson setup build
The Meson build system
Version: 1.11.2
Source dir: /Users/xyz/Downloads/libxkbcommon-1.3.1
Build dir: /Users/xyz/Downloads/libxkbcommon-1.3.1/build
Build type: native build
Project name: libxkbcommon
Project version: 1.3.1
C compiler for the host machine: cc (clang 10.0.0 "Apple LLVM version 10.0.0 (clang-1000.10.44.4)")
C linker for the host machine: cc ld64 409.12
Host machine cpu family: x86_64
Host machine cpu: x86_64
Compiler for C supports arguments -fno-strict-aliasing: YES 
Compiler for C supports arguments -fsanitize-undefined-trap-on-error: YES 
Compiler for C supports arguments -Wno-unused-parameter: YES 
Compiler for C supports arguments -Wno-missing-field-initializers: YES 
Compiler for C supports arguments -Wpointer-arith: YES 
Compiler for C supports arguments -Wmissing-declarations: YES 
Compiler for C supports arguments -Wformat=2: YES 
Compiler for C supports arguments -Wstrict-prototypes: YES 
Compiler for C supports arguments -Wmissing-prototypes: YES 
Compiler for C supports arguments -Wnested-externs: YES 
Compiler for C supports arguments -Wbad-function-cast: YES 
Compiler for C supports arguments -Wshadow: YES 
Compiler for C supports arguments -Wlogical-op: NO 
Compiler for C supports arguments -Wdate-time: YES 
Compiler for C supports arguments -Wwrite-strings: YES 
Compiler for C supports arguments -Wno-documentation-deprecated-sync: YES 
Found pkg-config: YES (/usr/local/bin/pkg-config) 0.29.2
Found CMake: /usr/local/bin/cmake (3.28.1)
Run-time dependency xkeyboard-config found: NO  (tried pkg-config, framework and cmake)
Has header "unistd.h" : YES 
Checking if "__builtin_expect" links: YES 
Header "unistd.h" has symbol "eaccess" : NO 
Header "unistd.h" has symbol "euidaccess" : NO 
Header "sys/mman.h" has symbol "mmap" : YES 
Header "stdlib.h" has symbol "mkostemp" : NO 
Header "fcntl.h" has symbol "posix_fallocate" : NO 
Header "string.h" has symbol "strndup" : YES 
Header "stdio.h" has symbol "asprintf" : YES 
Header "stdlib.h" has symbol "secure_getenv" : NO 
Header "stdlib.h" has symbol "__secure_getenv" : NO 
Message: C library does not support secure_getenv, using getenv instead
Header "getopt.h" has symbol "getopt_long" : YES 
Header "limits.h" has symbol "PATH_MAX" : YES 
Checking if "-Wl,--version-script" links: NO 
Program scripts/map-to-def found: YES (/Users/xyz/Downloads/libxkbcommon-1.3.1/scripts/map-to-def)
Program bison found: YES (/usr/local/bin/bison)
Found pkg-config: YES (/usr/local/bin/pkg-config) 0.29.2
Run-time dependency xcb found: YES 1.14
Run-time dependency xcb-xkb found: YES 1.14
Run-time dependency libxml-2.0 found: NO  (tried pkg-config, framework and cmake)

meson.build:353:17: ERROR: Dependency "libxml-2.0" not found (tried pkg-config, framework and cmake)

also:

$ meson introspect build -i --compilers --dependencies --machines
Introspection file build/meson-info/intro-compilers.json does not exist.

Logfile reports:

Run-time dependency xcb-xkb found: YES 1.14
Determining dependency 'libxml-2.0' with pkg-config executable '/usr/local/bin/pkg-config'
env[PKG_CONFIG_PATH]: /usr/local/opt/curl/lib/pkgconfig
env[PKG_CONFIG]: /usr/local/bin/pkg-config
-----------
Called: `/usr/local/bin/pkg-config --modversion libxml-2.0` -> 1
stderr:
Package libxml-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libxml-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libxml-2.0' found
-----------
Finding framework path by running:  cc -v -E - -I/usr/local/opt/curl/include -I/usr/local/opt/ruby/include 

Looking for framework libxml-2.0 in /System/Library/Frameworks
Looking for framework libxml-2.0 in /Library/Frameworks
CMake binary for host machine is cached.
Preliminary CMake check failed. Aborting.

For some reason

$ echo $PKG_CONFIG_PATH
/usr/local/opt/curl/lib/pkgconfig

Perhaps a missing option to cc is the culprit? Please advise.

Thanks.

[eli-schwartz]

Logfile reports:

Called: `/usr/local/bin/pkg-config --modversion libxml-2.0` -> 1
stderr:
Package libxml-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `libxml-2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libxml-2.0' found

so perhaps absence of libxml-2.0.pc is the culprit? Please advise.

This original question was correct. It is the absence of libxml-2.0.pc that is the problem.

For some reason

$ echo $PKG_CONFIG_PATH
/usr/local/opt/curl/lib/pkgconfig

This is entirely normal. That variable refers to "additional directories to augment the builtin system locations", and homewbrew etc often augment that variable.

Perhaps a missing option to cc is the culprit? Please advise.

The compiler is totally uninvolved in looking up dependencies.

[eli-schwartz]

This works no different from e.g. autotools as well. If you want to build software against other software, you need the other software to be available, both as runtime dylibs and as development headers / pkgconfig files.

On macOS, typically the former will be installed but not the latter. This is because...

macOS isn't really intended to be a developer platform, the libraries that ship with the OS are intended just for the OS itself to use. That is basically why homebrew exists... so you can install developer libraries via homebrew and build all your software against homebrew instead of against the macOS system libraries. Same basic logic applies to macports, etc.

Attempting to build software without using homebrew is... challenging.

[WuMingIT]

Looking for framework libxml-2.0 in /System/Library/Frameworks
Looking for framework libxml-2.0 in /Library/Frameworks

refers to looking for libxml-2.0.pc then?

[bonzini]

No, frameworks are a different Apple-specific concept that doesn't need the pc file. Meson tries it because it's running on macOS.

[WuMingIT]

I am confused. If macOS is granted an additional search procedure - and is not necessarily relying on a .pc file - could I instruct meson to look in /usr/lib/ for the actual library and /usr/include/libxml2/libxml for header files?

[bonzini]

No the extra search procedure is specific to libraries found via the -F and -framework compiler options that are available on macOS; it's not for any path.

[WuMingIT]

I understand now. Thanks for explaining.