bug#43508: gcc-mesboot@4.9.4 has duplicate ‘gcc-mesboot1’ input

[Ludovic Courtès]

Hello,

The gcc-mesboot@4.9.4 package has the same ‘gcc-mesboot1’ input twice:

--8<---------------cut here---------------start------------->8---
$ guix describe
Generacio 159   Sep 18 2020 08:55:27    (nuna)
  guix 98b89f4
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 98b89f432103b66efacee0bcba41a94148b8e870
$ cat $(guix gc --references $(guix build -e '(@@ (gnu packages commencement) 
gcc-mesboot)' -d) |grep gcc-mesboot-4.9.4-guile-builder)
  […]
  (define %build-inputs
    (quote
     (("source" . 
"/gnu/store/56km255bk1s880yn6rxw4wj3crm2pshk-gcc-4.9.4.tar.xz")
      ("gcc-wrapper" . 
"/gnu/store/w527yvvbn3m8m243x7q9h6bal035ry9h-gcc-mesboot1-wrapper-4.6.4")
      ("gcc" . 
"/gnu/store/q7f07gpd9sq9krc68gxa73vbqmk06y0a-gcc-mesboot1-4.6.4")   ; ⇐
      ("headers" . 
"/gnu/store/aj9plwk7k9ma17bbcwd7l8f48z1bim66-glibc-headers-mesboot-2.16.0")
      ("libc" . 
"/gnu/store/wgb70ir475v4vhg4bcjzv4h2kaa93qj7-glibc-mesboot-2.16.0")
      ("binutils" . 
"/gnu/store/mza1k0mgr8ab407yzavwwz07ly7221wy-binutils-mesboot-2.20.1a")
      ("xz" . "/gnu/store/r1zsxj7wlvw1aa1ifv3nyrrjag44pc9s-xz-mesboot-5.0.0")
      ("gcc" . 
"/gnu/store/q7f07gpd9sq9krc68gxa73vbqmk06y0a-gcc-mesboot1-4.6.4")   ; ⇐
--8<---------------cut here---------------end--------------->8---

This is visible at the package level:

--8<---------------cut here---------------start------------->8---
scheme@(gnu packages commencement)> ,pp (package-native-inputs gcc-mesboot)
$11 = (("gcc-wrapper"
  #<package gcc-mesboot1-wrapper@4.6.4 gnu/packages/commencement.scm:2321 
7f3f5dd12960>)
 ("gcc"
  #<package gcc-mesboot1@4.6.4 gnu/packages/commencement.scm:1992 7f3f5dd12d20>)
 ("headers"
  #<package glibc-headers-mesboot@2.16.0 gnu/packages/commencement.scm:2183 
7f3f5dd12aa0>)
 ("libc"
  #<package glibc-mesboot@2.16.0 gnu/packages/commencement.scm:2291 
7f3f5dd12a00>)
 ("binutils"
  #<package binutils-mesboot@2.20.1a gnu/packages/commencement.scm:2108 
7f3f5dd12b40>)
 ("xz"
  #<package xz-mesboot@5.0.0 gnu/packages/commencement.scm:2041 7f3f5dd12c80>)
 ("gcc"
  #<package gcc-mesboot1@4.6.4 gnu/packages/commencement.scm:1992 7f3f5dd12d20>)
--8<---------------cut here---------------end--------------->8---

I noticed it while trying to address
<https://issues.guix.gnu.org/38100>: it prevents the simple solution of
using (delete-duplicates input-drvs) in ‘bag->derivation’.  (Apart from
that this issue is harmless, but I think we’d better be strict about
this sort of things deep down in the graph.)

Ludo’.