[MacPorts] #65183: rust: Portfile can fail to parse depending on build_arch

[MacPorts]

#65183: rust: Portfile can fail to parse depending on build_arch
---------------------+---------------------------------
  Reporter:  jmroot  |      Owner:  MarcusCalhoun-Lopez
      Type:  defect  |     Status:  assigned
  Priority:  Normal  |  Milestone:
 Component:  ports   |    Version:
Resolution:          |   Keywords:
      Port:  rust    |
---------------------+---------------------------------

Comment (by MarcusCalhoun-Lopez):

 Clearly, a port should **always** be able to parse validly regardless of
 platform or architecture.\\
 Anything less should be fixed right away.

 However, I cannot reproduce this error.\\
 The command `port info rust build_arch=i386` does **not** produce an error
 on my system:
 {{{
 macOS 10.12.6 16G2136 x86_64
 Xcode 9.2 9C40b
 Command Line Tools 9.2.0.0.1.1510905681
 }}}
 So we must now figure out what is different about the system where the
 error does occur.

 This is just a guess, but `port info rust muniversal.architectures=""`
 **did** produce an error on my system.

 `muniversal.architectures` should not be empty, but if it were, the error
 could be traced as follows:
 * from [https://github.com/macports/macports-
 ports/blob/2e5f412343dd07fbafd88cd069d1a31fc73cd5f8/_resources/port1.0/group/rust-1.0.tcl#L327
 the end] `proc rust.add_bootstrap_components`
 * since `rustc_version` is not set in [https://github.com/macports
 /macports-
 ports/blob/2e5f412343dd07fbafd88cd069d1a31fc73cd5f8/_resources/port1.0/group/rust-1.0.tcl#L149
 in the for loop]
 * since `muniversal.architectures` [https://github.com/macports/macports-
 ports/blob/2e5f412343dd07fbafd88cd069d1a31fc73cd5f8/lang/rust/Portfile#L70
 is empty]

 Is there any reason to suspect that `muniversal.architectures`
 [https://github.com/macports/macports-
 ports/blob/2e5f412343dd07fbafd88cd069d1a31fc73cd5f8/_resources/port1.0/group/muniversal-1.1.tcl#L46
 is empty] on the system where the error occurs?

-- 
Ticket URL: <https://trac.macports.org/ticket/65183#comment:2>
MacPorts <https://www.macports.org/>
Ports system for macOS