From: Rafael Sadowski <rafael@sizeofvoid.org>
Subject: Re: [libcxx22] fallout
To: Theo Buehler <tb@theobuehler.org>
Cc: ports@openbsd.org
Date: Wed, 26 Aug 2026 07:00:59 +0200

On Tue Aug 25, 2026 at 10:24:53PM +0200, Theo Buehler wrote:
> On Tue, Aug 25, 2026 at 09:55:53PM +0200, Rafael Sadowski wrote:
> > On Fri Aug 21, 2026 at 02:15:34PM +0200, Theo Buehler wrote:
> > > Here is the directly libcxx22-related breakage of my first bulk.
> > > 
> > > There may be a few more because mono got stuck with a weird error.  And
> > > I did not try to build the V8 monsters: codex, deno, chromiums and a few
> > > others because my machine isn't beefy enough. I don't think anything
> > > super important is directly affected or hiding behind those. So as far
> > > as ports are concerned, I think we can land libcxx22 whenever we want:
> > > 
> > > audio/ncmpcpp
> > > audio/rubberband
> > > cad/freecad
> > > databases/mongodb/44
> > > games/cataclysm-dda
> > > games/dxx-rebirth
> > > games/flightgear/base
> > > games/keeperrl
> > > mail/kopano/core
> > > misc/subsurface
> > > shells/fish/v3
> > > textproc/lttoolbox
> > > 
> > > 
> > > misc/subsurface
> > > /usr/ports/pobj/subsurface-6.0.5459/subsurface-e0fbda77ef203a5a2539465e9fa44df56e2f5a9e/core/uemis-downloader.cpp:434:9: error: null passed to a callee that requires a non-null argument [-Werror,
> > > -Wnonnull]
> > >   434 |         return NULL;
> > >       |                ^~~~
> > 
> > OK?
> > 
> > diff --git a/misc/subsurface/patches/patch-core_uemis-downloader_cpp b/misc/subsurface/patches/patch-core_uemis-downloader_cpp
> > new file mode 100644
> > index 00000000000..85c640885f3
> > --- /dev/null
> > +++ b/misc/subsurface/patches/patch-core_uemis-downloader_cpp
> > @@ -0,0 +1,21 @@
> > +Index: core/uemis-downloader.cpp
> > +--- core/uemis-downloader.cpp.orig
> > ++++ core/uemis-downloader.cpp
> > +@@ -194,7 +194,7 @@ static struct dive *get_dive_by_uemis_diveid(device_da
> > + 		if (object_id == d->dcs[0].diveid)
> > + 			return d.get();
> > + 	}
> > +-	return NULL;
> > ++	return {};
> 
> Maybe there is some C++ magic that fixes this, but I don't think this is
> right. The return value is assigned to a non_owned_dive (since the
> divelist is an owning_table containing unique_ptrs). Doesn't this leak?

Yes and no, with "std::unique_ptr::get", you access the raw pointer and
then leave the protection provided by "std::unique_ptr" (which is the
owner of this pointer). It's all a bit messy.

I think the "return null" case is one that never happens, but the
function has to return something.

But one thing is wrong: when we trigger "return null", we're dereferencing
the pointer. I've fixed that below and instead of "{}" we can retrun
nullptr which is the same but more explicit.

> 
> > + }
> > + 
> > + /* send text to the importer progress bar */
> > +@@ -431,7 +431,7 @@ static std::string first_object_id_val(std::string_vie
> > + 			return res;
> > + 		}
> > + 	}
> > +-	return NULL;
> > ++	return {};
> 
> this seems fine.

Yes this returns a copy of an empty std::string.

> 
> > + }
> > + 
> > + /* ultra-simplistic; it doesn't deal with the case when the object_id is
> 


diff --git a/misc/subsurface/patches/patch-core_uemis-downloader_cpp b/misc/subsurface/patches/patch-core_uemis-downloader_cpp
new file mode 100644
index 00000000000..de09a8338da
--- /dev/null
+++ b/misc/subsurface/patches/patch-core_uemis-downloader_cpp
@@ -0,0 +1,30 @@
+Index: core/uemis-downloader.cpp
+--- core/uemis-downloader.cpp.orig
++++ core/uemis-downloader.cpp
+@@ -194,7 +194,7 @@ static struct dive *get_dive_by_uemis_diveid(device_da
+ 		if (object_id == d->dcs[0].diveid)
+ 			return d.get();
+ 	}
+-	return NULL;
++	return nullptr;
+ }
+ 
+ /* send text to the importer progress bar */
+@@ -431,7 +431,7 @@ static std::string first_object_id_val(std::string_vie
+ 			return res;
+ 		}
+ 	}
+-	return NULL;
++	return {};
+ }
+ 
+ /* ultra-simplistic; it doesn't deal with the case when the object_id is
+@@ -914,7 +914,7 @@ static bool process_raw_buffer(device_data_t *devdata,
+ 				int diveid = 0;
+ 				from_chars(val, diveid);
+ 				non_owned_dive = get_dive_by_uemis_diveid(devdata, diveid);
+-				if (dive_no != 0)
++				if (non_owned_dive && dive_no != 0)
+ 					non_owned_dive->number = dive_no;
+ 				if (for_dive)
+ 					*for_dive = diveid;