can't use c++17 with gcc 5

[dvirtz]

installing with compiler.cppstd=17 compiler=gcc compiler.version=5 fails even though GCC 5 supports c++17.
This is because the checks in

conan/conans/client/build/cppstd_flags.py

Line 256 in fb5004d

if Version(gcc_version) >= "5.1":

are done with minor versions and '5' < '5.1'.
On the other hand, setting compiler.version=5.4 fails due to https://github.com/conan-io/conan-package-tools/blob/e3c29b9e3e2dd72c661beff2674fc3d4f4b16a7a/cpt/builds_generator.py#L88

Environment Details (include every applicable attribute)

• Operating System+version: Ubuntu 16.04
• Compiler+version: gcc 5.4
• Conan version: 1.39.0
• Python version: 3.7.10

Steps to reproduce (Include if Applicable)

see above

Logs (Executed commands with output) (Include/Attach if Applicable)

Traceback (most recent call last):
  File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/root/.vscode-server/extensions/ms-python.python-2021.8.1105858891/pythonFiles/lib/python/debugpy/__main__.py", line 45, in <module>
    cli.main()
  File "/root/.vscode-server/extensions/ms-python.python-2021.8.1105858891/pythonFiles/lib/python/debugpy/../debugpy/server/cli.py", line 444, in main
    run()
  File "/root/.vscode-server/extensions/ms-python.python-2021.8.1105858891/pythonFiles/lib/python/debugpy/../debugpy/server/cli.py", line 285, in run_file
    runpy.run_path(target_as_str, run_name=compat.force_str("__main__"))
  File "/usr/lib/python3.7/runpy.py", line 263, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "/usr/lib/python3.7/runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/root/conan-recipes/scripts/build_recipe.py", line 95, in <module>
    run_autodetect()
  File "/usr/lib/python3.7/site-packages/bincrafters/build_autodetect.py", line 113, in run_autodetect
    builder.run()
  File "/usr/lib/python3.7/site-packages/cpt/packager.py", line 584, in run
    self.run_builds(base_profile_name=base_profile_name)
  File "/usr/lib/python3.7/site-packages/cpt/packager.py", line 679, in run_builds
    r.run()
  File "/usr/lib/python3.7/site-packages/cpt/runner.py", line 136, in run
    lockfile=self._lockfile)
  File "/usr/lib/python3.7/site-packages/conans/client/conan_api.py", line 93, in wrapper
    return f(api, *args, **kwargs)
  File "/usr/lib/python3.7/site-packages/conans/client/conan_api.py", line 364, in create
    self.app.cache, self.app.out, lockfile=lockfile)
  File "/usr/lib/python3.7/site-packages/conans/client/conan_api.py", line 1559, in get_graph_info
    phost.process_settings(cache)
  File "/usr/lib/python3.7/site-packages/conans/model/profile.py", line 53, in process_settings
    settings_preprocessor.preprocess(self.processed_settings)
  File "/usr/lib/python3.7/site-packages/conans/client/settings_preprocessor.py", line 9, in preprocess
    _check_cppstd(settings)
  File "/usr/lib/python3.7/site-packages/conans/client/settings_preprocessor.py", line 46, in _check_cppstd
    compiler_cppstd, "compiler.cppstd")
  File "/usr/lib/python3.7/site-packages/conans/client/settings_preprocessor.py", line 40, in check_flag_available
    available))
conans.errors.ConanException: The specified 'compiler.cppstd=17' is not available for 'gcc 5'. Possible values are ['98', 'gnu98', '11', 'gnu11', '14', 'gnu14']'

[Renari]

This is probably disabled because not all features of C++17 are supported until GCC7.

https://en.cppreference.com/w/cpp/compiler_support#cpp17

[dvirtz]

but it's enabled with 5.1

…

On Thu, 12 Aug 2021, 21:10 Arie Miller, ***@***.***> wrote: This is probably disabled because not all features of C++17 are supported until GCC7. https://en.cppreference.com/w/cpp/compiler_support#cpp17 — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#9417 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB2ORDOUTBRYMLMB4UQDEBTT4QFDHANCNFSM5CBDCQLA> .

[lasote]

Thanks for reporting. I think this is a Conan bug, thank you for reporting.

[memsharded]

#9431 will fix this for 1.40, the flag added will be -std=c++1z

[dvirtz]

Thanks!

…

On Mon, 16 Aug 2021 at 10:57, James ***@***.***> wrote: #9431 <#9431> will fix this for 1.40, the flag added will be -std=c++1z — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#9417 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB2ORDKN33LRTO7LI2DAXG3T5DAIHANCNFSM5CBDCQLA> .