Add CI images for clang with libstdc++

[Bronek]

No description provided.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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[augmentcode]

🤖 Augment PR Summary

Summary: This PR extends the CI image build pipeline to add Clang images that link against libstdc++ in addition to the existing libc++-based Clang images.

Changes:

• Enhances the build-ci-image composite action with file and target inputs, and improves input documentation.
• Updates ci-build.yml to use a shared build context (ci/build) with per-compiler Dockerfiles and per-target multi-stage builds.
• Adds new matrix entries clang-libstdcxx:21 and clang-libstdcxx:22 and publishes them as separate CI images.
• Refactors the Clang Dockerfile into a base stage plus clang and clang-libstdcxx target stages.
• Extracts Catch2 build/install logic into a reusable ci/build/build-catch.sh script and reuses it from both GCC and Clang images.
• Adds ci/.gitignore intended to keep ci/build tracked despite the repo-level build/ ignore rule.

Technical Notes: The workflow now selects the Docker build stage via target (e.g. clang-libstdcxx) while still parameterizing compiler/debian versions via build args.

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[augmentcode]

Review completed. 4 suggestions posted.

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[augmentcode]

(.github/actions/build-ci-image/action.yml:22) The build_args example uses comma-separated values (e.g. GCC_RELEASE=16,DEBIAN_VERSION=trixie), but docker/build-push-action treats build-args as a newline-separated list; following the example could pass a single malformed build-arg instead of multiple.

Severity: low

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(.github/actions/build-ci-image/action.yml:43) Composite action inputs are strings, so if: ${{ inputs.push }} will treat the literal 'false' as truthy; the "Export digest"/"Upload digest" steps may run even when pushing is disabled.

Severity: medium

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(ci/.gitignore:1) Because the repo-level .gitignore ignores build/ (which matches ci/build/**), !build re-includes only the directory entry; new files under ci/build can still remain ignored unless you also re-include its contents.

Severity: low

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[augmentcode]

(ci/build/clang/Dockerfile:52) build-catch.sh declares #!/bin/bash but is executed via sh, so adding any bash-specific syntax later would break the image build in a non-obvious way.

Severity: low

Other Locations

• ci/build/clang/Dockerfile:70
• ci/build/gcc/Dockerfile:61

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