clang-5.0 depends on gcc6 instead of gcc7

[mouse07410 (Mouse)]

Both clang-5.0 and gcc7 support C++17, which is the main reason I need these ports now.

However clang-5.0 shows gcc6 as its library dependency - thus forcing me to spend almost 1GB on the already pretty much filled-up disk.

Coud you please update clang-5.0 dependencies in such a way that it would accept both gcc6 and gcc7 (i.e., won't install gcc6 is gcc7 is already installed), or just require gcc7?

Thanks!

$ port info clang-5.0
clang-5.0 @5.0.0_2 (lang)
Variants:             [+]analyzer, assertions, debug, [+]libstdcxx, universal

Description:          Clang is an LLVM native C/C++/Objective-C compiler, which aims to deliver amazingly fast compiles
                      (e.g. about 3x faster than GCC when compiling Objective-C code in a debug configuration),
                      extremely useful error and warning messages and to provide a platform for building great source
                      level tools. The included Clang Static Analyzer is a tool that automatically finds bugs in your
                      code, and is a great example of the sort of tool that can be built using the Clang frontend as a
                      library to parse C/C++ code.
Homepage:             http://clang.llvm.org/

Extract Dependencies: xz
Build Dependencies:   cmake
Library Dependencies: libxml2, libomp, llvm-5.0, python27, libedit, libffi, ncurses, zlib, libcxx, gcc6
Runtime Dependencies: clang_select, ld64, perl5
Platforms:            darwin
License:              NCSA
Maintainers:          Email: jeremyhu@macports.org, GitHub: jeremyhu
                      Email: larryv@macports.org
$

[jeremyhu (Jeremy Huddleston Sequoia)]

#54773 is tracking changes here.

[jeremyhu (Jeremy Huddleston Sequoia)]

Or rather #54766