Ardour 6.8 can't load the HEAD version of the LV2 and VST3 plugin

[paulfd]

The issue is with the symbol pango_font_metrics_get_height(...) which comes from libpango 1.44 and up. Ardour currently bundles in libpango 1.40.4. I added a pull request on our VSTGUI fork which includes a runtime check for the libpango version before calling this method. This solves the problem for the VST3 version, since Ardour calls dlopen with the RTDL_LAZY flag for VST plugins. However, this does not solve the issue for the LV2 plugin, because suil loads UIs with the RTDL_NOW flag and thus the UI fails to instantiate due to the missing symbol.

I think we should push the runtime check upstream in VSTGUI. To allow LV2 UIs, I think our solutions are either:

• Remove the code from our VSTGUI fork and use it until Ardour updates libpango. I haven't seen a visual impact when disabling this part of the code to be honest, but I haven't checked deeply either.
• Statically link in pango/cairo in the UI

[jpcima]

Hi, I thought to have already fixed this in upstream vstgui.
I recall to have sent a PR after the vstgui author introduced this call, which indeed broke Ardour.