failed to call external command due to encoding issue when meson setup

[trim21]

Describe the bug
A clear and concise description of what the bug is.

I'm on windows and using chcp 65001, $Env:PYTHONUTF8 = '1' and $Env:PYTHONIOENCODING = 'UTF-8' in powershell, which will make meson failed to setup.

I have clang and msvc both installed, and when running meson setup build it failed with this error:

task: [meson] meson setup build
The Meson build system
Version: 1.6.1
Source dir: C:\Users\Trim21\proj\asio-loop
Build dir: C:\Users\Trim21\proj\asio-loop\build
Build type: native build
Project name: asioloop
Project version: dev
Exception in thread Thread-5 (_readerthread):
Traceback (most recent call last):
  File "C:\Users\Trim21\AppData\Roaming\uv\python\cpython-3.10.16-windows-x86_64-none\lib\threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "C:\Users\Trim21\AppData\Roaming\uv\python\cpython-3.10.16-windows-x86_64-none\lib\threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\Trim21\AppData\Roaming\uv\python\cpython-3.10.16-windows-x86_64-none\lib\subprocess.py", line 1515, in _readerthread
    buffer.append(fh.read())
  File "C:\Users\Trim21\AppData\Roaming\uv\python\cpython-3.10.16-windows-x86_64-none\lib\codecs.py", line 322, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xce in position 142: invalid continuation byte
Traceback (most recent call last):
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\mesonmain.py", line 193, in run
    return options.run_func(options)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\msetup.py", line 365, in run
    app.generate()
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\msetup.py", line 188, in generate
    return self._generate(env, capture, vslite_ctx)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\msetup.py", line 210, in _generate
    intr = interpreter.Interpreter(b, user_defined_options=user_defined_options)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreter\interpreter.py", line 322, in __init__
    self.parse_project()
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\interpreterbase.py", line 129, in parse_project
    self.evaluate_codeblock(self.ast, end=1)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\interpreterbase.py", line 195, in evaluate_codeblock
    raise e
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\interpreterbase.py", line 187, in evaluate_codeblock
    self.evaluate_statement(cur)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\interpreterbase.py", line 201, in evaluate_statement
    return self.function_call(cur)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\interpreterbase.py", line 528, in function_call
    res = func(node, func_args, kwargs)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\decorators.py", line 237, in wrapper
    return f(*nargs, **wrapped_kwargs)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreterbase\decorators.py", line 556, in wrapper
    return f(*wrapped_args, **wrapped_kwargs)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreter\interpreter.py", line 1321, in func_project
    self.add_languages(proj_langs, True, MachineChoice.HOST)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreter\interpreter.py", line 1490, in add_languages
    success = self.add_languages_for(args, required, for_machine)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\interpreter\interpreter.py", line 1533, in add_languages_for
    comp = compilers.detect_compiler_for(self.environment, lang, for_machine, skip_sanity_check, self.subproject)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\compilers\detect.py", line 105, in detect_compiler_for
    comp = compiler_from_language(env, lang, for_machine)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\compilers\detect.py", line 102, in compiler_from_language
    return lang_map[lang](env, for_machine) if lang in lang_map else None
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\compilers\detect.py", line 616, in detect_cpp_compiler
    return _detect_c_or_cpp_compiler(env, 'cpp', for_machine)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\compilers\detect.py", line 468, in _detect_c_or_cpp_compiler
    linker = guess_win_linker(env, compiler, cls, version, for_machine, invoked_directly=False)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\linkers\detect.py", line 72, in guess_win_linker
    if 'LLD' in o.split('\n', maxsplit=1)[0]:
AttributeError: 'NoneType' object has no attribute 'split'

meson.build:1:0: ERROR: Unhandled python exception

    This is a Meson bug and should be reported!
task: Failed to run task "meson": exit status 2

this can be avoided by unset PYTHONUTF8 but it will be default in py315 so there maybe a issue in the future

To Reproduce
Please include your meson.build files, preferably as a minimal toy example showing the issue.
You may need to create simple source code files (don't include private/proprietary code).

I'm really not sure what cause this, and I can't re-produce it in CI.

my meson file is empty with only project meta:

project(
    'asioloop',
    'cpp',
    default_options: [
        'c_std=c11',
        'cpp_std=c++20',
        'buildtype=release',
        'debug=false',
        'default_library=static',
    ],
    meson_version: '>= 1.5.0',
    version: 'dev',
)

Expected behavior
A clear and concise description of what you expected to happen.

it should setup or report meson file missing target or something.

system parameters

• Is this a cross build or just a plain native build (for the same computer)? no
• what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.) windows 10
• what Python version are you using: Python 3.10.16
• what meson --version 1.6.1
• what ninja --version if it's a Ninja build: 1.11.1.git.kitware.jobserver-1

[eli-schwartz]

File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\compilers\detect.py", line 468, in _detect_c_or_cpp_compiler
    linker = guess_win_linker(env, compiler, cls, version, for_machine, invoked_directly=False)
  File "C:\Users\Trim21\proj\asio-loop\.venv\lib\site-packages\mesonbuild\linkers\detect.py", line 72, in guess_win_linker
    if 'LLD' in o.split('\n', maxsplit=1)[0]:
AttributeError: 'NoneType' object has no attribute 'split'

meson.build:1:0: ERROR: Unhandled python exception

So, we attempt to figure out what the linker is by running: subprocess.Popen(compiler + check_args, stdout=subprocess.PIPE, stderr=subprocess.PIPE) and then .communicate(None)ing to get stdout/stderr, which apparently left us with stdout == None in your case. I'm not sure how that particular result came about. Given that avoiding UTF-8 mode in python worked, we can assume that your compiler/linker wanted to send a result that made python basically freak out when trying to interpret it.