From 021155df7fad97a5ae1baa354e15a03ea14500b4 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Thu, 17 Aug 2023 11:49:32 +0200
Subject: [PATCH] config.guess: Detect Android (as opposed to GNU/Linux)

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.

[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

* config.guess (Linux|GNU|GNU/*): Detect Android.
* doc/config.guess.1: Regenerate.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 config.guess       | 6 +++++-
 doc/config.guess.1 | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/config.guess b/config.guess
index b187213..47c9f0f 100755
--- a/config.guess
+++ b/config.guess
@@ -4,7 +4,7 @@
 
 # shellcheck disable=SC2006,SC2268 # see below for rationale
 
-timestamp='2023-07-20'
+timestamp='2023-08-17'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -155,6 +155,9 @@ Linux|GNU|GNU/*)
 
 	set_cc_for_build
 	cat <<-EOF > "$dummy.c"
+	#if defined(__ANDROID__)
+	LIBC=android
+	#else
 	#include <features.h>
 	#if defined(__UCLIBC__)
 	LIBC=uclibc
@@ -169,6 +172,7 @@ Linux|GNU|GNU/*)
 	LIBC=musl
 	#endif
 	#endif
+	#endif
 	EOF
 	cc_set_libc=`$CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep '^LIBC' | sed 's, ,,g'`
 	eval "$cc_set_libc"
diff --git a/doc/config.guess.1 b/doc/config.guess.1
index 17482f7..fbf7c6b 100644
--- a/doc/config.guess.1
+++ b/doc/config.guess.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.48.5.
-.TH CONFIG.GUESS "1" "July 2023" "GNU config.guess (2023-07-20)" "User Commands"
+.TH CONFIG.GUESS "1" "August 2023" "GNU config.guess (2023-08-17)" "User Commands"
 .SH NAME
 config.guess \- guess the build system triplet
 .SH SYNOPSIS