We patch meson to look at LIBname_VERSION (set by SHARED_LIBS in
ports).  Our patch doesn't work when a meson.build has
library(name_prefix: '').  Both net/dino and net/libupnpp have patches
removing name_prefix: '' to work around this problem.  I offer this
diff for name_prefix.

A typical library looks like
	library('what', sources)
and prepends 'lib', so it is libwhat.so.${LIBwhat_VERSION}.

A library with named_prefix: might be
	library('libwhat', sources, name_prefix: '')
which should have the same name, but might rename some generated
files (like from 'what.pc' to 'libwhat.pc').  The version variable
should be LIBwhat_VERSION, not LIBlibwhat_VERSION.

I rarely write Python, so it would help if someone checks my code.  It
runs before the default self.prefix = 'lib' is set.  Given a typical
library without name_prefix, hasattr(self, 'prefix') is false, so it
should pick the same version variable as before.  The pick should
change only if there is a name_prefix and the prefixed name begins
with 'lib'.

This diff has built all the packages on my amd64 desktop, but has never
been in a bulk.  I packaged net/libupnpp without its patch-meson_build.
I tried to package net/dino without the 2nd chunk of
patch-libdino_meson_build; it failed because some files changed names
(dino.h to libdino.h and dino.vapi to libdino.vapi) and I had not
updated PLIST.

Is this good enough to commit?
--gkoehler

Index: Makefile
===================================================================
RCS file: /cvs/ports/devel/meson/Makefile,v
diff -u -p -r1.151 Makefile
--- Makefile	23 Sep 2025 09:55:38 -0000	1.151
+++ Makefile	11 Nov 2025 21:57:17 -0000
@@ -5,6 +5,7 @@ GH_ACCOUNT=		mesonbuild
 GH_PROJECT=		meson
 GH_TAGNAME=		1.9.1
 EPOCH=			0
+REVISION=		0
 
 CATEGORIES=		devel
 
Index: patches/patch-mesonbuild_build_py
===================================================================
RCS file: /cvs/ports/devel/meson/patches/patch-mesonbuild_build_py,v
diff -u -p -r1.59 patch-mesonbuild_build_py
--- patches/patch-mesonbuild_build_py	25 Aug 2025 07:12:17 -0000	1.59
+++ patches/patch-mesonbuild_build_py	11 Nov 2025 21:57:17 -0000
@@ -9,12 +9,17 @@ Index: mesonbuild/build.py
  )
  from .options import OptionKey
  
-@@ -2584,6 +2585,26 @@ class SharedLibrary(BuildTarget):
+@@ -2584,6 +2585,31 @@ class SharedLibrary(BuildTarget):
              if self.darwin_versions is None and self.soversion is not None:
                  # If unspecified, pick the soversion
                  self.darwin_versions = (self.soversion, self.soversion)
 +        if is_openbsd():
-+            self.libversion = os.getenv('LIB' + self.name + '_VERSION')
++            libname = self.name
++            if hasattr(self, 'prefix'):
++                prefixed_name = self.prefix + self.name
++                if prefixed_name[:3] == 'lib':
++                    libname = prefixed_name[3:]
++            self.libversion = os.getenv('LIB' + libname + '_VERSION')
 +            if (self.libversion is None and
 +                    self.soversion is not None and
 +                    len(self.soversion) != 0 and
@@ -30,13 +35,13 @@ Index: mesonbuild/build.py
 +                    f.write("# SHARED_LIBS+= {:<25}<obsd version> # <orig version>\n".format("<libname>"))
 +                    f.close
 +                f = open(shared_libs_log, 'a')
-+                f.write("SHARED_LIBS += {:<25} {} # {}\n".format(self.name, \
++                f.write("SHARED_LIBS += {:<25} {} # {}\n".format(libname, \
 +                        self.soversion, self.ltversion_orig))
 +                f.close
  
          # Visual Studio module-definitions file
          self.process_vs_module_defs_kw(kwargs)
-@@ -2635,6 +2656,8 @@ class SharedLibrary(BuildTarget):
+@@ -2635,6 +2661,8 @@ class SharedLibrary(BuildTarget):
          # filename. If ltversion != soversion we create an soversion alias:
          # libfoo.so.0 -> libfoo.so.0.100.0
          # Where libfoo.so.0.100.0 is the actual library