[MacPorts] #67296: cargo_fetch and rust PG "formal" bug

[MacPorts]

#67296: cargo_fetch and rust PG "formal" bug
-------------------------+--------------------
 Reporter:  RJVB         |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:
 Keywords:               |       Port:
-------------------------+--------------------
 There's what one could call a formal bug in the post-extract sections of
 the `cargo_fetch` and `rust` PortGroups:

 `"${cargo.home}/config.toml` is not re-written but appended to if
 `cargo.crates` nor `cargo.crates_github` are set.

 This is a moot point for normal users, but for port maintainers who do not
 systematically do a `port clean` before attempting another build during
 port maintainance it leads to build failures as `cargo` apparently doesn't
 accept multiple `[build]` sections in that file.

 Adding an else clause with

 {{{
         # make sure config.toml doesn't contain any left-overs in this
 case too
         file delete -force "${cargo.home}/config.toml"
 }}}

 in local copies of the PGs fixed this issue for me.

-- 
Ticket URL: <https://trac.macports.org/ticket/67296>
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