Build status:

• Linux
• Windows

Which toolchain are you using?

GCC on linux

Can you provide instructions for replicating the issue?

This was changed in #67 to fix #57.

Micro-CDR is not a C++ project -- the tests use it though, but there the sub-CMakeLists.txt configures it.

I only saw it in a CI build, and the same build works locally. I'm not sure where the difference comes from. The change fixes the CI build though, and given the instructions further down $<$<COMPILE_LANGUAGE:CXX>, it's clearly incorrect if C++ isn't enabled.

The alternative (and IMO better) way is to remove $<COMPILE_LANGUAGE:CXX>. It shouldn't be required, as it's C code.

given the instructions further down $<$<COMPILE_LANGUAGE:CXX>, it's clearly incorrect if C++ isn't enabled.

$<COMPILE_LANGUAGE:CXX> is a generator expression, specifically a conditional which checks whether CXX has been enabled previously (see the docs).

What makes you suggest it's incorrect?

It checks for the language used for a given compilation unit, not whether a language is enabled.
It does not mention the case where a language is specified by the expression, but not enabled by the project (possibly because it seems like a logical expectation), so the behavior might depend on the cmake version.

I can reproduce with cmake version 3.10.2, with this case:

project(test LANGUAGES C)

add_executable(test test.c)
target_compile_options(test PRIVATE -Wall
	-Wextra
	-Wshadow
	$<$<COMPILE_LANGUAGE:CXX>:-Wnon-virtual-dtor>
	)

CMake Error at CMakeLists.txt:4 (target_compile_options):
  Error evaluating generator expression:

    $<COMPILE_LANGUAGE:CXX>

  $<COMPILE_LANGUAGE:...> Unknown language.

cmake version 3.22.2 does not produce an error.

Build status:

• Linux
• Windows

@pablogs9 do you have any reason not to remove COMPILE_LANGUAGE:CXX?

Build status:

• Linux
• Windows

LGTM