[package] m4/1.4.18: Does not compile with Clang

Package and Environment Details (include every applicable attribute)

• Package Name/Version: m4/1.4.18
• Operating System+version: Linux Ubuntu 20.04
• Compiler+version: Clang 10
• Conan version: conan 1.26.1
• Python version: Python 3.8.2

Conan profile (output of conan profile show default or conan profile show <profile> if custom profile is in use)

$ conan profile show clang
Configuration for profile clang:

[settings]
os=Linux
os_build=Linux
arch=x86_64
arch_build=x86_64
compiler=clang
compiler.version=10
compiler.libcxx=libstdc++11
build_type=Release
[options]
[build_requires]
[env]

Steps to reproduce (Include if Applicable)

$ conan install m4/1.4.18@_/_ -pr clang -b missing

Logs (Include/Attach if Applicable)

$ conan install m4/1.4.18@_/_ -pr clang -b missing
Configuration:
[settings]
arch=x86_64
arch_build=x86_64
build_type=Release
compiler=clang
compiler.libcxx=libstdc++11
compiler.version=10
os=Linux
os_build=Linux
[options]
[build_requires]
[env]

m4/1.4.18: WARN: Package is corrupted, removing folder: /home/wouter/.conan/data/m4/1.4.18/_/_/package/91a4ede3f059ef52815958df6195330b87cd719c
Installing package: m4/1.4.18
Requirements
    m4/1.4.18 from 'conan-center' - Cache
Packages
    m4/1.4.18:91a4ede3f059ef52815958df6195330b87cd719c - Build

Installing (downloading, building) binaries...
m4/1.4.18: WARN: Build folder is dirty, removing it: /home/wouter/.conan/data/m4/1.4.18/_/_/build/91a4ede3f059ef52815958df6195330b87cd719c
m4/1.4.18: Copying sources to build folder
m4/1.4.18: Building your package in /home/wouter/.conan/data/m4/1.4.18/_/_/build/91a4ede3f059ef52815958df6195330b87cd719c
m4/1.4.18: Generator txt created conanbuildinfo.txt
m4/1.4.18: Calling build()
m4/1.4.18: Calling:
 > source_subfolder/configure '--prefix=/home/wouter/.conan/data/m4/1.4.18/_/_/package/91a4ede3f059ef52815958df6195330b87cd719c' '--bindir=${prefix}/bin' '--sbindir=${prefix}/bin' '--libexecdir=${prefix}/bin' '--libdir=${prefix}/lib' '--includedir=${prefix}/include' '--oldincludedir=${prefix}/include' '--datarootdir=${prefix}/share' 
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking whether make supports nested variables... (cached) yes
checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/home/wouter/.conan/data/m4/1.4.18/_/_/build/91a4ede3f059ef52815958df6195330b87cd719c':
configure: error: C compiler cannot create executables
See `config.log' for more details
m4/1.4.18: 
m4/1.4.18: ERROR: Package '91a4ede3f059ef52815958df6195330b87cd719c' build failed
m4/1.4.18: WARN: Build folder /home/wouter/.conan/data/m4/1.4.18/_/_/build/91a4ede3f059ef52815958df6195330b87cd719c
ERROR: m4/1.4.18: Error in build() method, line 75
	autotools = self._configure_autotools()
while calling '_configure_autotools', line 42
	self._autotools.configure(args=conf_args, configure_dir=self._source_subfolder)
	ConanException: Error 77 while executing source_subfolder/configure '--prefix=/home/wouter/.conan/data/m4/1.4.18/_/_/package/91a4ede3f059ef52815958df6195330b87cd719c' '--bindir=${prefix}/bin' '--sbindir=${prefix}/bin' '--libexecdir=${prefix}/bin' '--libdir=${prefix}/lib' '--includedir=${prefix}/include' '--oldincludedir=${prefix}/include' '--datarootdir=${prefix}/share' 

[madebr]

From what I understand: The settings sections is used to populate the settings object. But the build helpers won’t automagically find/use the correct build toolchain. e.g. for cross building the gcc compiler might have a aarch64-linux-gnu- prefix. So you can set CC=aarch64-linux-gnu-gcc in the env section.

[steakhal]

Please remove the CC_FOR_BUILD= from your profile and try #4003

Seems to work for me with both gcc-10 and clang-10 this way. Thank you for your effort.