[PATCH] config.guess: Detect Android (as opposed to GNU/Linux)

[Bruno Haible]

Hi,

Here's a patch to recognize Android environments.

Such environments are "apps" with POSIX-like tools. Today, the most frequently
used one is Termux [1][2][3]; on devices with Android versions before 5.0
one can use Terminal-IDE [4][5].

config.sub already supports this environment:

  $ sh config.sub armv7l-linux-androideabi
  armv7l-unknown-linux-androideabi

I've built many GNU packages in this environment, with the following recipe:
  CONFIG_SHELL=$PREFIX/bin/sh; export CONFIG_SHELL
  CC="clang -ferror-limit=0" CXX="clang++ -ferror-limit=0"; export CC CXX
  ./configure --host=armv7l-linux-androideabi --prefix=$HOME/local

The Termux people have compiled or ported more than 1000 packages as well [6].

But the requirement to pass the --host parameter each time is an annoyance.
Without it, based only on the results of uname, config.guess guesses

  $ sh config.guess
  armv7l-unknown-linux-gnueabi

and many configuration results are wrong (because Android has many functions
in libc without declaring them in the .h files, depending on the so-called
"Android API level"), leading to many compilation errors.

With the attached patch, it produces

  $ sh config.guess
  armv7l-unknown-linux-androideabi

The patch does not include an addition to the config.guess test suite, since
the uname values are:
  $ uname -m
  armv7l
  $ uname -r
  4.19.127
  $ uname -s
  Linux
  $ uname -v
  #1 SMP PREEMPT Tue Apr 4 16:54:58 IST 2023
  $ uname -p
  unknown
which maps to armv7l-unknown-linux-gnueabi.

Bruno

[1] https://github.com/termux/termux-app
[2] https://f-droid.org/en/packages/com.termux/
[3] https://wiki.termux.com/wiki/Main_Page
[4] https://en.wikibooks.org/wiki/Android/Terminal_IDE
[5] http://www.spartacusrex.com/terminalide.htm
[6] https://github.com/termux/termux-packages/tree/master/packages

0001-config.guess-Detect-Android-as-opposed-to-GNU-Linux.patch
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