[MacPorts] #62018: fltk-config --cxxflags returns invalid value on macOS Big Sur 11.1

[MacPorts]

#62018: fltk-config --cxxflags returns invalid value on macOS Big Sur 11.1
--------------------------------------------------+------------------------
 Reporter:  markuskimius                          |      Owner:  (none)
     Type:  defect                                |     Status:  new
 Priority:  Normal                                |  Milestone:
Component:  ports                                 |    Version:  2.6.4
 Keywords:  fltk-devel, Big Sur, macOS 11.1, SDK  |       Port:  fltk-devel
--------------------------------------------------+------------------------
 On a fresh install of macOS Big Sur 11.1, fltk-config (in fltk-devel
 package) returns a parameter,
 `-isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk` which
 references an SDK that exists in macOS Big Sur 11.0 but not in 11.1. One
 possible result is that attempting to compile a program with this invalid
 parameter can result in the following error:

 {{{
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/stdio.h:107:15:
 fatal error: 'stdio.h' file not found
 }}}

 The parameter in question is returned when `fltk-config` is run with a few
 different possible argument, one of which is `fltk-config --cxxflags`
 whose output is as follows on my system:

 {{{
 -I/opt/local/include -pipe -Os -stdlib=libc++
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk
 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_THREAD_SAFE -D_REENTRANT
 }}}

 Yet, on my freshly installed macOS Big Sur 11.1, these are the SDKs in
 /Library/Developer/CommandLineTools/SDKs, none of which is MacOSX11.0.sdk:

 {{{
 lrwxr-xr-x 1 root wheel  14 Jan  9 12:17 MacOSX.sdk -> MacOSX11.1.sdk/
 drwxr-xr-x 8 root wheel 256 Jul  9  2020 MacOSX10.15.sdk/
 drwxr-xr-x 7 root wheel 224 Nov 30 07:33 MacOSX11.1.sdk/
 }}}

 Upon review, it was found that `/opt/local/bin/fltk-config` has
 `MacOSX11.0.sdk` hard-coded in the script. Modifying it to reference
 `MacOSX.sdk` instead fixed the compilation problems for me.

 This is the version of `fltk-devel` installed on my system:

 {{{
   fltk-devel @20201213-d8635887_0 (active)
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/62018>
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