You did not report the explicit assertion failure notice. So, starting a little
earlier in the file for the extraction:

Assertion failed: ((!TII->analyzeBranch(*PrevBB, TBB, FBB, Cond) || !PrevBB->canFallThrough()) && "Unexpected block with un-analyzable fallthrough!"), function buildCFGChains, file /usr/local/poudriere/jails/main-armv7/usr/src/contrib/llvm-project/llvm/lib/CodeGen/MachineBlockPlacement.cpp, line 2816.
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /usr/bin/c++ -DHAVE_CONFIG_H -DHAVE_DNSSD -DHAVE_GIFLIB -DHAVE_UPNP -DHAVE_WEBM -DQTCOLORPICKER_STATICALLY_LINKED -DQT_CORE_LIB -DQT_GUI_LIB -DQT_MULTIMEDIA_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_SVG_LIB -DQT_WIDGETS_LIB -I/wrkdirs/usr/ports/graphics/drawpile/work/.build/src/desktop -I/wrkdirs/usr/ports/graphics/drawpile/work/Drawpile-2.1.20/src/desktop -I/wrkdirs/usr/ports/graphics/drawpile/work/.build/src/desktop/drawpile_autogen/include -I/wrkdirs/usr/ports/graphics/drawpile/work/.build -I/wrkdirs/usr/ports/graphics/drawpile/work/Drawpile-2.1.20/src/desktop/../libclient -I/wrkdirs/usr/ports/graphics/drawpile/work/Drawpile-2.1.20/src/desktop/bundled/QtColorWidgets/include -isystem /usr/local/include/qt5 -isystem /usr/local/include/qt5/QtNetwork -isystem /usr/local/include/qt5/QtCore -isystem /usr/local/lib/qt5/mkspecs/freebsd-clang -isystem /usr/local/include/KF5/KArchive -isystem /usr/local/include/KF5 -isystem /usr/local/include/KF5/KDNSSD -isystem /usr/local/include/qt5/QtGui -isystem /usr/local/include -isystem /usr/local/include/qt5/QtWidgets -isystem /usr/local/include/qt5/QtMultimedia -isystem /usr/local/include/qt5/QtSvg -Wall -pedantic -Wextra -std=c++11 -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -DNDEBUG -fPIC -MD -MT src/desktop/CMakeFiles/drawpile.dir/toolwidgets/brushsettings.cpp.o -MF src/desktop/CMakeFiles/drawpile.dir/toolwidgets/brushsettings.cpp.o.d -o src/desktop/CMakeFiles/drawpile.dir/toolwidgets/brushsettings.cpp.o -c /wrkdirs/usr/ports/graphics/drawpile/work/Drawpile-2.1.20/src/desktop/toolwidgets/brushsettings.cpp

Comment 2 Yuri Victorovich 2024-01-12 06:36:41 UTC

All information I know is in the URL link.

(In reply to Yuri Victorovich from comment #2)

So you put the burden of finding the basic description for
the problem on the folks that would try to process your
submittal instead of including it in the description. When
an explicit assertion failure notice is present, I'd suggest
always including it in the description and having the
summary line mention "assertion failure" (it is more
specific than "crashes" and indicates some about the
kind of information available).

Comment 4 Yuri Victorovich 2024-01-12 06:59:47 UTC

(In reply to Mark Millard from comment #3)

The idea that missing assertion was not intentional is a very evasive idea.

(In reply to Yuri Victorovich from comment #4)

Sorry if my note seemed to indicate that you had the intent
of omitting the assertion instead of your possibly just being
a little rushed and, so, not finding possibly better
information for the description.

I try to defer my compiler-failure submittals until after I've
had some time to find out if there is an assertion failure
notice to include in the description if there is not time
for that up front.

Comment 6 Mark Johnston 2024-01-26 19:29:28 UTC

> PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
> Preprocessed source(s) and associated run script(s) are located at:
> c++: note: diagnostic msg: /tmp/brushsettings-800a79.cpp
> c++: note: diagnostic msg: /tmp/brushsettings-800a79.sh

Is it possible to include these files in the report?

Comment 7 Yuri Victorovich 2024-01-26 19:43:06 UTC

I don't have access to the arm machines where failures occur.

(In reply to Mark Johnston from comment #6)

Not only are the official package builders limited to logs,
but poudiere builds in general do not preserve those files:
no material from /tmp is in the compressed tar generated if
one has it configured to generate those tar files on failure.
The builder's /tmp likely does not last long after the
failure.

But I've vague memories of some command line option for
clang/clang++ to make those failure files go in the local
directory instead, so inside what the tar file covers.
That still requires a separate build attempt in a different
environment.

(In reply to Mark Johnston from comment #6)

I found my old notes in another bugzilla entry:

QUOTE(outer)
FYI, relative to potential build infrastructure behavior, clang/clang++ has:

QUOTE
-fcrash-diagnostics-dir=<dir>
Specify where to write the crash diagnostics files; defaults to the usual location for temporary files.
END QUOTE

So redirecting to someplace that poudriere(-devel) with -w includes
in the (compressed) tar archive for build failures is a possibility.
END QUOTE(outer)

Sometimes touching a Makefile with the likes of (partial diff output):

QUOTE
+CFLAGS+=   -fcrash-diagnostics-dir=.
+CPPFLAGS+= -fcrash-diagnostics-dir=.
END QUOTE

allows for that capture in the tar file for the failure if it has been
enabled.

This seems to have been fixed by the update to Drawpile 2.2.0.  Is there any value in keeping the bug open?

Comment 11 Yuri Victorovich 2024-01-28 19:13:27 UTC

(In reply to John F. Carr from comment #10)

This is up to @freebsd-toolchain to decide.

Comment 12 Dimitry Andric 2024-01-29 08:27:55 UTC

If there aren't any repro files I think it is hard to do anything.