Walkthrough

The changes introduce new options in the CMake configuration for enabling C++ support based on specific conditions. Three options are added: WITH_GTEST, WITH_FUZZERS, and WITH_BENCHMARKS, with default values of ON, OFF, and OFF, respectively. A conditional block checks if any of these options are enabled, executing the enable_language(CXX) command if at least one is true. The previous declarations of these options are removed, ensuring they are defined only once in the new section.

Changes

Sequence Diagram(s)

sequenceDiagram
    participant CMake as CMakeLists.txt
    participant Condition as IF Statement
    participant CXX as C++ Language Enabler

    CMake->>Condition: Check WITH_GTEST, WITH_FUZZERS, or WITH_BENCHMARKS flags
    alt One or more flags are true
        Condition->>CXX: Call enable_language(CXX)
    else No flags are true
        Condition->>CMake: Proceed without enabling C++
    end

According to CMake documentation CFLAGS is only used if CMAKE_C_FLAGS is unset and CXXFLAGS is only used if CMAKE_CXX_FLAGS is unset.

https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_FLAGS.html:

CMAKE_C_FLAGS: Initialized by the CFLAGS environment variable.
CMAKE_CXX_FLAGS: Initialized by the CXXFLAGS environment variable.

As I see, CMAKE_*_FLAGS are overridden only in:

Maybe it makes sense to fix these workflows instead of duplicate C*FLAGS value in CMAKE_*_FLAGS?

Maybe it makes sense to fix these workflows instead of duplicate CFLAGS value in CMAKE__FLAGS?

pkgcheck.sh use both configure and cmake, so it is special case.

The issue is with cmake populating CMAKE_C_FLAGS and CMAKE_CXX_FLAGS too late. So only way to set the variables early enough is to use CFLAGS and CXXFLAGS when coverity scan is enabled. Without the workaround both variables are always set to -O0 despite what was passed to cmake.

When coverity scan is not enabled, there is no issue and the workaround is skipped.

The issue is with cmake populating CMAKE_C_FLAGS and CMAKE_CXX_FLAGS too late.

What do you mean by too late?
I thought that it was initialized during the project(LANGUAGE) call. Or was I wrong?

The issue is with cmake populating CMAKE_C_FLAGS and CMAKE_CXX_FLAGS too late.

What do you mean by too late? I thought that it was initialized during the project(LANGUAGE) call. Or was I wrong?

Clearly when I and dead2 tested, those variables were empty when cmake hit the function in the PR.

See for example https://github.com/zlib-ng/zlib-ng/actions/runs/14375470240/job/40306746506?pr=1892

This may be why I had to turn off gtest for PPC64LE ci run.

This may be why I had to turn off gtest for PPC64LE ci run.

You can verify that locally by re-enabling gtest for PPC64LE after checking out branch from this PR.

You can verify that locally by re-enabling gtest for PPC64LE after checking out branch from this PR.

Nope this PR doesn't fix that.

Nope this PR doesn't fix that.

At least this workaround allows enabling benchmarks on 32-bit ARM with hard-float on CI.

See for example https://github.com/zlib-ng/zlib-ng/actions/runs/14375470240/job/40306746506?pr=1892

I have one idea. I'll check it now and write the result...

The issue is with cmake populating CMAKE_C_FLAGS and CMAKE_CXX_FLAGS too late.

What do you mean by too late? I thought that it was initialized during the project(LANGUAGE) call. Or was I wrong?

Clearly when I and dead2 tested, those variables were empty when cmake hit the function in the PR.

See for example https://github.com/zlib-ng/zlib-ng/actions/runs/14375470240/job/40306746506?pr=1892

@mtl1979 , @Dead2 , this is incorrect PR!

The C++ language is enabled too late. After the CMAKE_CXX_* variables are used.

We need to enable C++ directly in project().
Or conditionally, but BEFORE the line:

See fix commit phprus@0667808
and CI: https://github.com/phprus/zlib-ng/actions/runs/14418138299/job/40437352696

The C++ language is enabled too late. After the CMAKE_CXX_* variables are used.

We need to enable C++ directly in project(). Or conditionally, but BEFORE the line:

zlib-ng/CMakeLists.txt

Line 50 in e4a31e0

include(cmake/detect-arch.cmake)

See fix commit phprus@0667808 and CI: https://github.com/phprus/zlib-ng/actions/runs/14418138299/job/40437352696

A lot of operating systems don't come with C++ compiler installed by default. I'd rather enable C++ only when it's actually needed...

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.38%. Comparing base (e4a31e0) to head (7bc161c).
Report is 1 commits behind head on develop.

@@             Coverage Diff             @@
##           develop    #1902      +/-   ##
===========================================
- Coverage    83.42%   83.38%   -0.04%     
===========================================
  Files          144      144              
  Lines        12948    12948              
  Branches      2857     2857              
===========================================
- Hits         10802    10797       -5     
+ Misses        1202     1201       -1     
- Partials       944      950       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

A lot of operating systems don't come with C++ compiler installed by default. I'd rather enable C++ only when it's actually needed...

Yes, you are right.
I suggest enabling C++ earlier only if needed: phprus@b0832f2

The previous commit was a proof of concept only.

Yeah, this looks like a better solution 👍

Once this PR is merged, #1892 needs to be rebased for CI to pass on all except EL9...