Try to clean ELF header from generated executable when compiling for Android

[fabricio-p]

When the C compiler generates an executable on/for Android, the executable includes what is called an ELF header, and everytime you run it, it will always prints this

WARNING: linker: /some/path/to/executable: unsupported flags DT_FLAGS_1=0x8000001

When compiling C, you can clean the ELF header using the Makefile, but V has its own build system and strategy.
If the compilation is happening inside an Android device and the termux-elf-cleaner command is detected, run that with the path of the executable as the first argument. You can detect if the device is Android by check if one of the environment variables ANDROID_DATA or ANDROID_PATH are set.

[larpon]

@fabriciopashaj - can you provide a minimal project or some source code that I can run in termux to reproduce these messages?
(also the commands to get a working V compiler in termux would help me a lot!).
I don't use termux personally so some guide on how to kickstart V development would be highly appreciated (maybe we can even include it in the official docs if made short and general enough, not sure)

[fabricio-p]

Of course.
Run those commands to setup

apt update && apt upgrade
apt install git clang termux-elf-cleaner

If you create a, i.e. C file named main.c with the contents below

int main() {
  return 0;
}

and then you do:

cc main.c -o main
./main

It will print WARNING: linker: /data/data/com.termux/files/home/main: unsupported flags DT_FLAGS_1=0x8000001.
This happens because the executable has elf headers included. If you clean the executable and run it again

termux-elf-cleaner main
./main

Nothing will be printed.

To build V do this:

git clone https://github.com/vlang/v
cd v
make
./v symlink

And then you have it.

[larpon]

Of course.
Run those commands to setup

apt update && apt upgrade
apt install git clang termux-elf-cleaner

If you create a, i.e. C file named main.c with the contents below

int main() {
  return 0;
}

and then you do:

cc main.c -o main
./main

It will print WARNING: linker: /data/data/com.termux/files/home/main: unsupported flags DT_FLAGS_1=0x8000001.
This happens because the executable has elf headers included. If you clean the executable and run it again

termux-elf-cleaner main
./main

Nothing will be printed.

To build V do this:

git clone https://github.com/vlang/v
cd v
make
./v symlink

And then you have it.

Thanks @fabriciopashaj

[larpon]

@medvednikov @spytheman @spaceface777 - I can probably fix this relatively easy. I'm a little unsure if this is even V's job in the first place? Cleaning up after specific compiler executables with thirdparty tools if detected? What do you think? What's the general stance on this?

[fabricio-p]

The main issue is that it's annoying, especially when using the repl. For each line that is evaluated, the warning is printed and the terminal becomes polluted. Maybe add an option like -noelf.