[MacPorts] #65683: darktable: link failure for darktable-curve-tool, on 10.15

[MacPorts]

#65683: darktable: link failure for darktable-curve-tool, on 10.15
---------------------+-----------------------
 Reporter:  mascguy  |      Owner:  mascguy
     Type:  defect   |     Status:  assigned
 Priority:  Normal   |  Milestone:
Component:  ports    |    Version:  2.7.2
 Keywords:           |       Port:  darktable
---------------------+-----------------------
 While the previous build of this port succeeded on our 10.15 buildbot, the
 latest fails with a link error for the curve-tool utility:

 {{{
 Undefined symbols for architecture x86_64:
   "___kmpc_for_static_fini", referenced from:
       _.omp_outlined. in darktable-curve-tool.c.o
       _.omp_outlined..66 in darktable-curve-tool.c.o
   "___kmpc_for_static_init_4", referenced from:
       _.omp_outlined. in darktable-curve-tool.c.o
       _.omp_outlined..66 in darktable-curve-tool.c.o
   "___kmpc_fork_call", referenced from:
       _linearize_16bit in darktable-curve-tool.c.o
       _linearize_8bit in darktable-curve-tool.c.o
 ld: symbol(s) not found for architecture x86_64
 clang: error: linker command failed with exit code 1 (use -v to see
 invocation)
 make[2]: *** [share/darktable/tools/basecurve/darktable-curve-tool] Error
 1
 }}}

 Two changes have been made since the last successful build:
 * Blacklisting Xcode Clang < 1200
 * A `GraphicsMagick`-related patch, to disable signal handler registration
 by that library; issue:64252

 The link command for the previous successful build, is:

 {{{
 /usr/bin/clang++ -pipe -DNDEBUG -I/opt/local/include -stdlib=libc++
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
 -D_DARWIN_C_SOURCE -Wall -Wformat -Wformat-security -Wshadow -Wtype-limits
 -Wvla -Wthread-safety -Wno-unknown-pragmas -Wno-error=varargs
 -Wno-error=address-of-packed-member -O3 -DNDEBUG -arch x86_64 -mmacosx-
 version-min=10.15 -Wl,-search_paths_first -Wl,-headerpad_max_install_names
 -L/opt/local/lib
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
 -L/usr/lib
 "CMakeFiles/darktable-curve-tool.dir/darktable-curve-tool.c.o" "CMakeFiles
 /darktable-curve-tool.dir/exif-wrapper.cpp.o"
 -o darktable-curve-tool -Wl,-rpath,/opt/local/lib
 /opt/local/lib/libexiv2.dylib -lm
 }}}

 While the latest, is as follows. As expected, the only difference relates
 to Clang:

 {{{
 /opt/local/bin/clang++-mp-13 -pipe -DNDEBUG -I/opt/local/include
 -stdlib=libc++
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
 -D_DARWIN_C_SOURCE -Wall -Wformat -Wformat-security -Wshadow -Wtype-limits
 -Wvla -Wthread-safety -Wno-unknown-pragmas -Wno-error=varargs
 -Wno-error=address-of-packed-member -O3 -DNDEBUG -arch x86_64 -mmacosx-
 version-min=10.15 -Wl,-search_paths_first -Wl,-headerpad_max_install_names
 -L/opt/local/lib
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk
 -L/usr/lib
 "CMakeFiles/darktable-curve-tool.dir/darktable-curve-tool.c.o" "CMakeFiles
 /darktable-curve-tool.dir/exif-wrapper.cpp.o"
 -o darktable-curve-tool  -Wl,-rpath,/opt/local/lib
 /opt/local/lib/libexiv2.dylib -lm
 }}}

 Of note, when building locally on 10.15, I'm not able to reproduce the
 link error.

 Are the undefined symbols related to `libomp`, or something similar...?

-- 
Ticket URL: <https://trac.macports.org/ticket/65683>
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