[bug] profile detect does not try to use the compiler provided

[Ignition]

Environment details

• Operating System+version: Ubuntu 22.04.3 LTS
• Compiler+version: Ubuntu clang version 17.0.6
• Conan version: Conan version 2.0.16
• Python version: Python 3.10.12

Steps to reproduce

CC=clang-17 CXX=clang++-17 conan profile detect
I would expect it to use clang++-17 when detecting libcxx

Logs

detect_api: CC and CXX: clang-17, clang++-17 
detect_api: Found clang 17.0
detect_api: clang>=8, using the major as version
detect_api: WARN: compiler.libcxx check error: /bin/sh: 1: clang++: not found
...

[memsharded]

Hi @Ignition

Thanks for your report.
Yes, it seems that there could be a bug there, and the detection should be using CC/CXX defined compiler.

[memsharded]

@RubenRBS I am having a look how this could be improved:

• Breaking the detect_api interface, and make "detect_compiler" return: compiler, version, compiler_exe = detect_compiler(), so we can pass the compiler_exe as optional argument to detect_libcxx and others
• Make it optional to not break with detect_compiler(return_compiler_exe=True)
• Extract and re-use the logic that checks CC/CXX env-vars and call it again inside the detect_libcxx call. Not super robust, but doable

[czoido]

Closed by #15418 that add new detect_default_compiler function.
Should be release very soon in 2.0.17