[Buildroot] [for-next] package/rust: allow using python3 interpreter

[Romain Naour]

Hi Thomas,

Le 29/05/2020 à 23:14, Thomas Petazzoni a écrit :
> Hello Romain,
> 
> On Tue, 26 May 2020 20:20:37 +0200
> Romain Naour <romain.naour at gmail.com> wrote:
> 
>> Fedora packaging use python3 as python interpreter since rust 1.24.0 [1]
>> by removing python2 tests from configure script [2].
>>
>> Using python3 will help to remove python2 in a near future.
>>
>> [1] https://src.fedoraproject.org/rpms/rust/c/216b2d27716bf1031c526dbd0e01a1fa8e6d5aa2
>> [2] https://src.fedoraproject.org/rpms/rust/blob/216b2d27716bf1031c526dbd0e01a1fa8e6d5aa2/f/rust.spec#_314
>>
>> Signed-off-by: Romain Naour <romain.naour at gmail.com>
>> Cc: Titouan Christophe <titouan.christophe at railnova.eu>
>> Cc: Arnout Vandecappelle <arnout at mind.be>
>> Cc: Patrick Havelange <patrick.havelange at essensium.com>
> 
> Thanks, I have applied to next, but I have a few comments/questions,
> see below.
> 
>> diff --git a/package/rust/0002-configure-use-default-python-interpreter.patch b/package/rust/0002-configure-use-default-python-interpreter.patch
>> new file mode 100644
>> index 0000000000..34d97bb4cf
>> --- /dev/null
>> +++ b/package/rust/0002-configure-use-default-python-interpreter.patch
>> @@ -0,0 +1,37 @@
>> +From aca7abb537f5caf1c9f027cf65dd0f53fb664e73 Mon Sep 17 00:00:00 2001
>> +From: Romain Naour <romain.naour at gmail.com>
>> +Date: Tue, 26 May 2020 18:24:25 +0200
>> +Subject: [PATCH] configure: use default python interpreter
>> +
>> +Don't try to use python2 if available, use the python interpreter available
>> +in ouput/host/bin/python whateverer the python version is.
>> +
>> +Signed-off-by: Romain Naour <romain.naour at gmail.com>
>> +---
>> + configure | 12 ------------
>> + 1 file changed, 12 deletions(-)
>> +
>> +diff --git a/configure b/configure
>> +index eeb8d081d34..6014a982f47 100755
>> +--- a/configure
>> ++++ b/configure
>> +@@ -2,16 +2,4 @@
>> + 
>> + script="$(dirname $0)"/src/bootstrap/configure.py
>> + 
>> +-try() {
>> +-    cmd=$1
>> +-    shift
>> +-    T=$($cmd --version 2>/dev/null)
>> +-    if [ $? -eq 0 ]; then
>> +-        exec $cmd "$script" "$@"
>> +-    fi
>> +-}
>> +-
>> +-try python2.7 "$@"
>> +-try python27 "$@"
>> +-try python2 "$@"
>> + exec python $script "$@"
> 
> Shouldn't we try to find an upstreamable solution here, such as perhaps
> a PYTHON environment variable, or an argument to configure that allows
> to specify the path to the Python interpreter ?
> 
> But in fact, this path to the Python interpreter is already in the
> config.toml file that we generate, why isn't this path used ?

humm, It seems that this configure script is not used at all by rust package
since we use directly x.py...
So we can just drop this patch.

> 
>> diff --git a/package/rust/rust.mk b/package/rust/rust.mk
>> index 5d14fc6682..25153966f2 100644
>> --- a/package/rust/rust.mk
>> +++ b/package/rust/rust.mk
>> @@ -17,9 +17,16 @@ HOST_RUST_DEPENDENCIES = \
>>  	host-rust-bin \
>>  	host-cargo-bin \
>>  	host-openssl \
>> -	host-python \
>>  	$(BR2_CMAKE_HOST_DEPENDENCY)
>>  
>> +ifeq ($(BR2_PACKAGE_PYTHON3),y)
>> +HOST_RUST_PYTHON_VERSION = $(PYTHON3_VERSION_MAJOR)
>> +HOST_RUST_DEPENDENCIES += host-python3
>> +else
>> +HOST_RUST_PYTHON_VERSION = $(PYTHON_VERSION_MAJOR)
>> +HOST_RUST_DEPENDENCIES += host-python
>> +endif
> 
> I think we should start inverting this logic, i.e use host-python3 by
> default if there is no python interpreter selected for the target. We
> should do that not only here, but in all packages that have a logic
> like that: python3 should become our default, and python2 should become
> the exception.

Yes, with this change we can remove python3-<module> added to provide python3
modules. I hope packages that still use python2 will only require the python2
interpreter without any additional modules.

Best regards,
Romain


> 
> Thanks!
> 
> Thomas
>