GSL @2.6: build fails after Mac OS Big Sur update

[mmphys]

GSL build fails with undefined symbols for x86_64 after update to Big Sur and Xcode 12.2.

NB: GSL is only port to fail - 141 other ports appear to work fine (list attached, myports_now.txt)

sudo port install gsl starts with the warning:

Warning: The macOS 11.0 SDK does not appear to be installed. Ports may not build correctly. Warning: You can install it as part of the Xcode Command Line Tools package by running `xcode-select --install'.

then fails with:

Error: Failed to build gsl: command execution failed

But SDK seems present:

$ xcrun --sdk macosx11.0 --show-sdk-path /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.0.sdk $ xcode-select -print-path /Applications/Xcode.app/Contents/Developer

Log (attached) shows link failure as follows:

:info:build Undefined symbols for architecture x86_64: :info:build "_cblas_caxpy", referenced from: :info:build _gsl_blas_caxpy in libgslblas.a(blas.o) ... :info:build "_cblas_ztrsv", referenced from: :info:build _gsl_blas_ztrsv in libgslblas.a(blas.o) :info:build ld: symbol(s) not found for architecture x86_64 :info:build clang: error: linker command failed with exit code 1 (use -v to see invocation)

[mmphys]

gsl port log

[mmphys]

List of other, working ports (port -qv installed)

[ryandesign (Ryan Carsten Schmidt)]

You have Xcode 12.2 and its copy of the macOS 11 SDK, but the gsl port is not configured to require Xcode; it uses the command line tools if available, and you apparently do not have a version of the command line tools that includes the macOS 11 SDK. Please update your command line tools to the Xcode 12.2 version.

[mmphys]

Updated log using command line tools and SDK 11.0

[mmphys]

Thank you. Command line tools updated to 12.2.

Warning is now gone, but failure appears to be the same. Updated log attached (main2.log)

[ryandesign (Ryan Carsten Schmidt)]

gsl's build system was generated with a version of libtool that misidentifies OS X 10.10 and later. We added a patch years ago to fix detection of 10.10 and later, but it does not cover macOS 11 and later. We need to update the patch from the one added to the libtool port months ago.

[ryandesign (Ryan Carsten Schmidt)]

In 2d348a95d23e10daec78d6e4c938adf691ad0578/macports-ports (master):

gsl: Fix build on macOS 11 and later

Closes: #61450

[mmphys]

Thank you so much!