[MacPorts] #61450: GSL @2.6: build fails after Mac OS Big Sur update

[MacPorts]

#61450: GSL @2.6: build fails after Mac OS Big Sur update
--------------------+--------------------
 Reporter:  mmphys  |      Owner:  (none)
     Type:  defect  |     Status:  new
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:  2.6.4
 Keywords:  bigsur  |       Port:  gsl
--------------------+--------------------
 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)}}}

-- 
Ticket URL: <https://trac.macports.org/ticket/61450>
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