rust: use copy, not system cp -r

[ryandesign (Ryan Carsten Schmidt)]

The rust portfile uses system on several occasions to call cp -r. Why does it do this, rather than use the Tcl copy procedure possibly in combination with glob and the expansion operator ({*})? For example, instead of:

system "cp -r ${workpath}/rustc-${rustc_version}-${rust_platform}/rustc/* ${rust_root}"

Why not (untested):

copy {*}[glob ${workpath}/rustc-${rustc_version}-${rust_platform}/rustc/*] ${rust_root}

[herbygillot (Herby Gillot)]

So I looked at this while looking at Rust 1.50.0 - cp -R works better than copy for this case because the source tarballs are all being extracted to the same destination and have overlapping directory paths, even though the leaf files are different.

TCL copy refuses to copy over existing directories even with -force:

From the TCL file copy documentation:

Trying to overwrite a non-empty directory, overwrite a directory with a file, or overwrite a file with a directory will all result in errors even if -force was specified.

[herbygillot (Herby Gillot)]

Closing as 'wontfix' since TCL copy isn't appropriate here.