On 2022-8-7 18:29 , Jordan Ellis Coppard via macports-dev wrote:
Hello,
I read in the docs that if MacPorts is installed anywhere other than
/opt/local that precompiled binaries can not be used. I cannot find this
statement again so I am unsure if there was additional explanation for
why; so.. why?
I'd like to be able to use MacPorts at a custom prefix but still also
use precompiled binaries sometimes (particularly those using Rust) due
to the incredibly long compilation times.
/Jordan
You may be remembering <https://trac.macports.org/wiki/FAQ#fromsource>.
Slight technicality, it's not that you can't use precompiled binaries
with prefixes other than /opt/local, but rather you can only use
precompiled binaries that were built for the prefix that you are using,
and the ones on packages.macports.org were built for /opt/local.
The most immediate problem with installing a package built for one
prefix into a different prefix is that simply extracting the package
will give you files in the wrong location. Easily fixable, right? But
then the files themselves can contain references to absolute paths that
are in the wrong prefix, for example mach-o files record what they are
linked with, scripts contain a shebang line that could say something
like "/opt/local/bin/python3.10", paths to config files may be baked
into executables, and so on.
All of this is fixable… given sufficient work. Some of it can be fairly
simply automated, some would require extensive rewriting of upstream
code. What you want is called "relocatable packages", and we currently
have no support for that in MacPorts. If it were added, it could not
automatically apply to all ports; we would have to manually flag which
ports are relocatable, since while some software may build in a way that
supports relocation out of the box, much will not.
- Josh
