apple-gcc42 is not supported on OS X versions newer than El Capitan.

[pshabunia-at-epam]

Cannot install virtualbox onto OSX Mojave

$ sudo port install virtualbox
--->  Computing dependencies for virtualbox
The following dependencies will be installed:
 apple-gcc42
 autoconf
 automake
 db48
 dbus
 lcms2
 libidl
 libmng
 libsdl
 libtool
 python27
 python2_select
 python_select
 qt4-mac
 sqlite3
 tiff
 vde2
 xorg-libX11
 xorg-libXau
 xorg-libXdmcp
 xorg-libXext
 xorg-libXrandr
 xorg-libpthread-stubs
 xorg-libxcb
 xorg-xcb-proto
 xorg-xorgproto
 xrender
Continue? [Y/n]:
--->  Fetching distfiles for apple-gcc42
Error: apple-gcc42 is not supported on OS X versions newer than El Capitan.
Error: Failed to fetch apple-gcc42: unsupported platform
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_lang_apple-gcc42/apple-gcc42/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port virtualbox failed

$ port version
Version: 2.5.4
$ port installed
The following ports are currently installed:
  bzip2 @1.0.6_0 (active)
  cctools @921_1+llvm70 (active)
  cmake @3.14.0_0 (active)
  curl @7.64.0_0+ssl (active)
  curl-ca-bundle @7.64.0_0 (active)
  cyrus-sasl2 @2.1.27_1+kerberos (active)
  expat @2.2.6_1 (active)
  gdbm @1.18.1_1 (active)
  gettext @0.19.8.1_0 (active)
  glib2 @2.58.3_0+x11 (active)
  gmp @6.1.2_1 (active)
  gnutls @3.6.6_1+doc (active)
  icu @58.2_2 (active)
  jpeg @9c_0 (active)
  kerberos5 @1.17_0 (active)
  kubectl @1.13.4_0 (active)
  ld64 @3_1+ld64_xcode (active)
  ld64-xcode @2_1 (active)
  libarchive @3.3.3_1 (active)
  libcomerr @1.44.5_0 (active)
  libcxx @5.0.1_4 (active)
  libedit @20181209-3.1_0 (active)
  libevent @2.1.8_0 (active)
  libffi @3.2.1_0 (active)
  libgcrypt @1.8.4_0 (active)
  libgpg-error @1.36_0 (active)
  libiconv @1.15_0 (active)
  libidn2 @2.1.1_0 (active)
  libpng @1.6.36_0 (active)
  libpsl @0.20.2-20190205_0 (active)
  libtasn1 @4.13_0 (active)
  libunistring @0.9.10_0 (active)
  libuv @1.27.0_0 (active)
  LibVNCServer @0.9.12_0 (active)
  libxml2 @2.9.9_0 (active)
  libxslt @1.1.33_1 (active)
  llvm-7.0 @7.0.1_1 (active)
  llvm_select @2_0 (active)
  lz4 @1.8.3_0 (active)
  lzo2 @2.10_0 (active)
  minikube @0.35.0_0+hyperkit (active)
  ncurses @6.1_0 (active)
  nettle @3.4.1_0 (active)
  openssl @1.0.2r_0 (active)
  p11-kit @0.23.15_0 (active)
  pcre @8.42_0 (active)
  pkgconfig @0.29.2_0 (active)
  readline @8.0.000_0 (active)
  tmux @2.8_0 (active)
  xar @1.6.1_0 (active)
  xz @5.2.4_0 (active)
  zlib @1.2.11_0 (active)
  zstd @1.3.8_0 (active)

[ryandesign (Ryan Carsten Schmidt)]

That's correct. There's no plan to change this. apple-gcc42 is ancient. If you need it, use an ancient version of Mac OS X that it runs on.

The virtualbox port needs to be updated so that it works with newer compilers and no longer requires apple-gcc42. There are existing tickets about that.

[yan12125 (Chih-Hsuan Yen)]

Yes, currently the issue is tracked in ​https://trac.macports.org/ticket/50622.