# Why didn't change \`CDT\_VERSION\`

**URL:** <https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166>\
**Category:** Dev\
**Created:** [August 29, 2025, 12:39am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166 "2025-08-29T00:39:41Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![FeelUs](https://avatars.discourse-cdn.com/v4/letter/f/7ab992/32.png) [@FeelUs](https://forum.graphviz.org/u/FeelUs)\
**Post date:** [August 29, 2025, 12:39am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/1 "2025-08-29T00:39:41Z")

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I look at history of libcdt API:  
[https://gitlab.com/graphviz/graphviz/-/blob/8.1.0/lib/cdt/cdt.h?ref\_type=tags#L87](https://gitlab.com/graphviz/graphviz/-/blob/8.1.0/lib/cdt/cdt.h?ref_type=tags#L87)  
[https://gitlab.com/graphviz/graphviz/-/blob/9.0.0/lib/cdt/cdt.h?ref\_type=tags#L89](https://gitlab.com/graphviz/graphviz/-/blob/9.0.0/lib/cdt/cdt.h?ref_type=tags#L89)  
[https://gitlab.com/graphviz/graphviz/-/blob/10.0.1/lib/cdt/cdt.h?ref\_type=tags#L88](https://gitlab.com/graphviz/graphviz/-/blob/10.0.1/lib/cdt/cdt.h?ref_type=tags#L88)  
Why after API changed, value of [`CDT_VERSION`](https://gitlab.com/graphviz/graphviz/-/blob/main/lib/cdt/cdt.h?ref_type=heads#L24) didn’t change?

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**Author:** ![smattr](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/smattr/32/85_2.png) [@smattr](https://forum.graphviz.org/u/smattr)\
**Post date:** [August 31, 2025, 12:53am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/2 "2025-08-31T00:53:30Z")

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I would say a mistake on our part. There have been a number of these version macros that have not been rigorously monitored nor updated during API changes. soversion also has not been well maintained, which we’ve been trying to correct recently. We should probably bump `CDT_VERSION` now to at least correct this problem going forwards.

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<div class="post-metadata">

**Author:** ![smattr](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/smattr/32/85_2.png) [@smattr](https://forum.graphviz.org/u/smattr)\
**Post date:** [August 31, 2025, 12:59am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/3 "2025-08-31T00:59:59Z")

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BTW are you using libcdt for something outside of Graphviz? I am not aware of any non-Graphviz use.

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<div class="post-metadata">

**Author:** ![FeelUs](https://avatars.discourse-cdn.com/v4/letter/f/7ab992/32.png) [@FeelUs](https://forum.graphviz.org/u/FeelUs)\
**Post date:** [August 31, 2025, 10:29am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/4 "2025-08-31T10:29:50Z")

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I’m just now wondering if I should use libcdt in my future projects

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**Author:** ![scnorth](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/scnorth/32/89_2.png) [@scnorth](https://forum.graphviz.org/u/scnorth)\
**Post date:** [August 31, 2025, 1:57pm UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/5 "2025-08-31T13:57:25Z")

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It’s quite old, there may be better choices that are actively maintained and take advantage of modern CPUs.

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<div class="post-metadata">

**Author:** ![smattr](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/smattr/32/85_2.png) [@smattr](https://forum.graphviz.org/u/smattr)\
**Post date:** [September 9, 2025, 12:14am UTC](https://forum.graphviz.org/t/why-didnt-change-cdt-version/3166/6 "2025-09-09T00:14:06Z")

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`CDT_VERSION` should be updated in the upcoming Graphviz 14.0.0, [API BREAK: cdt: update 'CDT\_VERSION' macro (!4517) · Merge requests · graphviz / graphviz · GitLab](https://gitlab.com/graphviz/graphviz/-/merge_requests/4517).