[PROTON-2365] Build failure without C++

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Affects Version/s: proton-c-0.33.0
• Component/s: build
• Flags: Patch
• Assignee: Unassigned
• Reporter: Fabrice Fontaine
• Created: 01/Apr/21 18:44
• Updated: 02/Apr/21 22:25
• Resolved: 02/Apr/21 22:25

Description

For an unknown reason, the following build failure is raised when the toolchain does not have a working C++ compiler (with cmake 3.18.4):

-- The CXX compiler identification is unknown
CMake Error at CMakeLists.txt:73 (enable_language):
 The CMAKE_CXX_COMPILER:
/home/giuliobenetti/autobuild/run/instance-3/output-1/host/bin/arm-linux-g++
is not a full path to an existing compiler tool.
Tell CMake where to find the compiler by setting either the environment
 variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
 to the compiler, or to the compiler name if it is in the PATH.

-- Configuring incomplete, errors occurred!

I don't understand why this build failure is raised because enable_language(CXX) is correctly protected by

check_language (CXX)
if (CMAKE_CXX_COMPILER)

Perhaps, there is a bug inside cmake, to fix it, check for BUILD_CPP