• Mike Parker (675/675) Apr 09 The D Language Foundation's December 2024 monthly meeting took
• Mike Shah (6/9) Apr 11 Thanks for the write up Mike!
• aberba (2/12) Apr 14 +1
• Anonymouse (2/3) Apr 15 Thanks!

Mike Parker <aldacron gmail.com> writes:

The D Language Foundation's December 2024 monthly meeting took 
place on Friday the 13th and lasted around an hour and a half.



The following people attended:

* Walter Bright
* Rikki Cattermole
* Ali Çehreli
* Jonathan M. Davis
* Max Haughton
* Martin Kinkelin
* Dennis Korpel
* Átila Neves
* Razvan Nitu
* Mike Parker
* Robert Schadek
* Steven Schveighoffer
* Adam Wilson





I reported that we had almost finalized the DConf stuff with the 
event planner. The preliminary costing put us right at the budget 
Symmetry had given us. I was waiting for all of that to be 
finalized so I could make the preliminary announcement. (It was a 
few weeks until [I was able to do 
that](https://forum.dlang.org/thread/ighxvsogmzycjlonarsu forum.dlang.org).)

I asked everyone if we wanted to have DConf Online in 2025. Átila 
asked if we needed it anymore. We'd started it because of the 
pandemic. I said I'd thought at the time that we'd continue it 
and have both DConf and DConf Online every year. But in 2024, we 
didn't have enough talks for two days of the Online version, so 
we only did one. I thought maybe we should still do it.

Steve said it almost seemed like we were trying to create talks 
just to have the online conference instead of having the 
conference for people with talks they wanted to share. It seemed 
more like work. Átila thought it had increased the quality of 
talks at DConf.

I said Steve had a good point. I had to push people for talks 
last time because I only received one unprompted submission. No 
one objected to skipping it this year. If there was demand for it 
later, we could try again.



Rikki noted that in the November meeting, I had brought up the 
need for us to be more professional. He thought we weren't 
looking good to the community right now and that we weren't 
meeting their expectations.

He'd considered things we were already committed to and thought 
we should set some target dates to complete them. If something 
was going wrong, we could find out about it, have it tracked by 
Razvan, and solve problems as they came up.

First, we had taken so much time on Editions that people thought 
it wasn't happening. Átila said he'd spoken to Razvan about it 
the day before. Rikki asked if there was any reason it hadn't 
been posted in the Development forum yet.

Átila said there were some things he needed to add to the 
document. He and Timon were in an ongoing discussion about. He 
needed to resolve that before finalizing the DIP. Other than 
that, it was 99% done. The real problem was figuring out who was 
going to implement it.

Rikki recommended the end of January as a potential target date. 
He thought Martin should be the one to implement it. He knew 
Martin had said he'd work on adding the external import path 
switch, but hadn't done it yet. That touched on the same area of 
the compiler, and if it were implemented incorrectly, there would 
be some problems with packages and things like that.

Martin said he'd told Rikki he'd implement the external path 
switch, but he hadn't said when. And no one else had requested it.

Rikki said the reason he was thinking of this was because the 
changes required for the external import paths and Editions would 
be similar. He thought Martin would prefer doing it because it 
would be a problem if they were done incorrectly.

Martin said it would be LDC-specific, so for that, yes, he was 
the number one choice. But his TODO list was huge. If more people 
were looking forward to it, his motivation to prioritize it would 
be higher.

Rikki said he could implement the switches in DMD because he knew 
about the simple stuff. Martin said it should be 50 or so code 
line changes. Rikki said he'd give it a go if Martin hadn't 
gotten to it by the end of January. Martin asked that no one give 
him any deadlines. He was reluctant to have deadlines on 
open-source projects.

Átila said he'd gone back through the comments on the DIP and 
there were fewer than he'd remembered. Most of them were from 
Timon, some of which Steve had replied to, but there were three 
primary concerns still outstanding.

Átila said Timon was concerned about safety bugs that we couldn't 
fix because they would entail breaking changes. We could fix them 
in another edition, but the concern was with the new edition 
calling into an old edition with safety bugs. Átila thought we'd 
have to live with that because he didn't know what else we could 
do.

The second thing was related to the command line and specifying 
editions for different modules. Átila thought that would entail a 
switch like `-mv`, but for editions rather than module names.

The third one was about having different APIs depending on the 
caller's edition. A library, for example, might want to have 
different declarations for its functions depending on who was 
calling into it and the caller's edition. A potential solution 
had recently come up in the form of a 'caller edition' trait.

I jumped in to say that because this was a DIP that Átila was 
authoring, approval required that we discuss it in a meeting 
before submitting it to Walter. We'd probably end up having a 
special session for it rather than doing it in a monthly. We 
could schedule that when the draft was ready. And the draft had 
to go through the Development forum first anyway.

Rikki next brought up tuples. He noted Timon wasn't in the 
meeting. Because Timon had been a lone wolf with tuples, Rikki 
thought it would be great if we could get some DIPs out of him by 
the end of 2025. He said Timon had an idea for tuple unpacking, 
but hadn't written a DIP yet.

Rikki's third target was related to AAs. He said Steve had 
already committed to removing the `TypeInfo` as part of the GC 
work. Due to some awful AA bugs, Rikki would like to see that 
kind of removal extended to AAs and the current implementation 
replaced with a templated one. He thought that was in line with 
what Steve was already working on.

Steve thought we needed to redo AA hooks, anyway. Rikki said the 
hooks themselves had to be converted to templates. Steve agreed 
and said there were a couple of hooks he'd thought were templated 
but actually were not.

Rikki said he'd like to see the AA compiler hooks moved into the 
same module as the implementation. Then anyone doing custom 
runtimes could copy and paste the entire module.

Razvan noted that Teodor Dutu had been looking into that, but was 
now busy working on his PhD. He didn't know how much time Teo 
had, but Razvan could contact him to see if he could look into it.

Next, Rikki said he expected we'd be getting to sum types soon. 
He said coroutines were his responsibility. He hoped to have a 
DIP in the queue in January.

(__UPDATE__: Rikki eventually submitted [the coroutines 
DIP](https://forum.dlang.org/post/asbfsajrtasfqewzbsce forum.dlang.org), and I
have since merged it into the repository. At the time of this post, he and I
are working on revising it.)

Next, he said, was the mess with DIP 1000. The community chatter 
was that it could never be turned on with Phobos v3. We needed to 
find a way to resolve that either by removing it or finding a 
path forward on escape analysis as a whole. We had to make some 
decisions on this in 2025.

Átila thought the way forward was Robert's idea of making things 
safe by default by limiting what you could do. There'd been a 
discussion about it in the forums. There'd been some pushback on 
it, but he couldn't recall what that was.

Walter said he'd gotten a PR merged for `-preview=safer`. It 
implemented all the safety checks by default, but without them 
being transitive. He was curious because he'd heard nothing about 
it.

Adam said a lot of that discussion had been happening in the 
Discord. Átila remembered proposing something and Paul Backus had 
said something that made sense, but he couldn't recall what the 
objection had been. The idea was about moving DIP 1000 to 
` trusted`. Adam thought that might have been in Discord.

Átila said he could email Paul. He remembered thinking that could 
be the way forward. Because then we'd get memory safety if people 
really wanted to do things that required `scope`. They wouldn't 
have to deal with that as we had to now. It had been a disaster 
trying to turn it on by default.

Walter said the safer preview didn't turn on DIP 1000. It was a 
bit of a modest step. He'd love to turn it on for compiler 
builds, but there was the bootstrapping problem. We couldn't seem 
to move to a more modern version of the compiler for 
bootstrapping.

I noted that we weren't going to settle this here and asked that 
we stick to Rikki's agenda item. We had several other agenda 
items to get through. If this other stuff needed further 
discussion, we could set aside some time for it later.

Rikki had no further targets to mention, but he emphasized he'd 
really like to see us finalize a decision on DIP 1000 in 2025 
because he really wanted to do escape analysis.



Walter said [the bitfields 
thing](https://github.com/dlang/dmd/pull/16084) had been around 
for a long time. He'd implemented the suggested improvements, the 
extra traits and such. He didn't see any barriers to getting it 
adopted.

He'd been looking at the DMD source code recently and thinking 
again that a part of it would be much nicer with bitfields 
instead of the kluge scheme in there now. It had gone back and 
forth on the newsgroups again and again, and it was always the 
same arguments one way or the other. He thought it was time to 
make a decision.

I reminded everyone that we'd decided in a May 2024 special 
session that if Walter implemented the suggested changes, then 
we'd be good with passing it on to Átila for approval. So the 
question then was whether we were still good with it.

Rikki said all of his remaining issues with it could be dealt 
with by an attribute later, so he was for it as it currently 
stood.

Adam said he'd discussed it with Walter recently, and Walter had 
told him the implementation was the de facto standard. 
Technically, C bitfields were implementation-defined, but 
everyone used the same implementation. Adam thought we had to go 
with that. As long as we were following the same implementation 
as everyone else, then go for it.

Átila said that so much code would break if someone changed that, 
it wasn't even funny. There might be some weird compiler or weird 
architecture out there, but there wasn't.

(__UPDATE__: Walter submitted the DIP a couple of weeks before 
this post. He and I are revising it, and I will soon pass it on 
to Átila for the verdict.)



Dennis pointed us at a pull request that a SAOC participant had 
submitted. It did two things.

First, it made `-verrors=context` the default, meaning that under 
every error message would be printed the source code line and a 
little caret pointing at the error. It also updated the test 
suite with a massive 10,000-line addition because every test 
there now had an extra line of code.

Since the error interface was such a big part of the compiler, he 
thought we shouldn't merge this kind of PR willy-nilly. He wasn't 
sure the test suite should have all those lines, even if we did 
turn on context error messages by default.

Walter said we could add a line to the test suite that turned 
them off because they were just noise as far as the tests were 
concerned. Dennis agreed and said the test runner could set 
`-verrors=none` or something. Átila agreed, but said that at 
least one test should check the caret, etc.

Dennis said there were a few tests with `context` set explicitly 
already. He did notice that the line numbers were correct in the 
test output, but many of the columns were wrong. For example, it 
would say something about the "foreach index", but then would 
point at the start of the `foreach` tokens rather than the index.

Max said he was mentoring the SAOC participant working on this. 
He said Razvan had approved the PR, but Max didn't want to touch 
it without some deliberation first because it was such a large 
change.

He said that at this point, any language with a compiler written 
in the last decade did this. GCC had had it for a decade, and 
Clang had had it forever. One of the things that initially drew 
people to Rust was that it had elaborate error messages.

Razvan said he didn't think the test suite was a problem. We 
could automatically update what was expected from a test and 
didn't need to get in there manually. If the caret was off by one 
or something, we should fix it, but he didn't see anything as a 
blocker.

Walter said many of the failed compilation errors had 30 or 40 
messages in the output. If `context` were turned on by default, 
that would become a blizzard that wasn't useful.

We didn't need context error messages in the test suite. We 
needed tests to show that context error messages were working. So 
he preferred turning it off for the test suite rather than 
merging that 10,000-line PR.

Jonathan said that regardless of whether we wanted the test suite 
to have this, we needed to merge the actual code changes without 
the changes to the test suite. Then we could review it properly 
and ensure it was working. We could go back later if we wanted to 
and enable it in the test suite piece by piece rather than all at 
once. which was just too much to look at.

Walter agreed. There were so many changes, you couldn't tell if 
anything was broken. Jonathan gave an example of a big change at 
work. They had decided to go at it piece by piece and uncovered 
several places where things would have gone wrong had they done 
it all at once.

Max said he'd initially asked his mentee to make the test suite 
changes because he wanted to ensure it all worked, not so much 
that it should be the default for the test suite. Someone else 
had attempted it before, but had segfaulted a lot. That was now 
obviously gone away.

Because of all the noise, he didn't think it should be the 
default for the test suite, but there should be a decent amount 
of exposure to the error messages for the compiler developers. If 
they were particularly noisy, that probably meant we should have 
better error messages. We could think of it as kind of a 
statement of our values.

He said that when working on DMD, you did tend to iterate by 
writing test cases. We should have some number of tests that 
exposed the full error messages so that the compiler developers 
weren't too detached from them.

Steve noted that Walter had said we should turn them on only to 
test the error message output. If you were looking for an exact 
error message when testing something else and expecting it to 
fail, then you didn't want them turned on for that. We could turn 
them on only when it was important to do so.

Max's point was that there was value in having it for more than 
just testing outputs.

Walter said it was just going to get in his way. He only had so 
many lines on his screen. When everything scrolled off the screen 
because the test generated 50 error messages, it became a 
maddening nuisance. It wasn't helpful to him at all when 
debugging. He knew it was the right default generally, but he 
dealt with failed compilations all the time. Having it on for all 
the tests would only be a major irritation.

I said it looked like the consensus was to accept having context 
error messages as the default, but to turn them off for the test 
suite. No one objected.

Dennis asked how to turn them off. There was `-verrors=none`, but 
that looked like there would then be no error messages. Max said 
they'd be painting the bikeshed soon. It would be something 
simple and short.

(__UPDATE__: [A subsequent 
PR](https://github.com/dlang/dmd/pull/20566) added 
`-verrors=simple` to disable context error messages.)



The student working on integrating DMD-as-a-library with 
D-Scanner had finally managed to get rid of D-Scanner's 
dependency on libdparse. He did it with [a huge pull 
request](https://github.com/dlang-community/D-Scanner/pull/964). 
The CI couldn't even run the tests.

Razvan had been reviewing the student's PRs for the past year, 
but this one was so big no one was going to review it. He 
wondered if we should go ahead and merge it once the tests passed 
after CI stopped being problematic and started running them. He 
brought it up in case anyone had other ideas. A 10,000-line PR 
was kind of scary to merge.

Steve thought we should be talking to the people who depended on 
D-Scanner for their projects, like IDE developers, Webfreak with 
code-d, or maybe the guy who was doing the Tree-sitter stuff. He 
didn't know who depended on what.

Razvan said he'd spoken with Webfreak about it and they were 
willing to merge it. Rikki thought we should just do it. We could 
always revert it if need be.

Steve asked if there were any open PRs on projects like dub that 
might be invalidated by this. Razvan said there shouldn't be. 
There might be some minor differences, but the behavior would 
largely be the same. Some of the checks would become more 
restrictive because D-Scanner wasn't able to do what the compiler 
did, but it would be able to once you hooked the compiler into 
it. Then it would catch more things. He thought that was a good 
thing.

Martin asked if we had a good idea of what the test coverage was 
in the test suite. Razvan said that they'd initially just taken 
the existing D-Scanner tests, but those were pretty slim. They 
discovered a lot of corner cases while they were implementing it 
and added quite a lot of tests as a result.

He didn't know if they were breaking any code out there, but in 
his experience, once they migrated a check from libdparse to 
dmdlib, the check got better. You would get more warnings, but 
that was because it was catching things that libdparse didn't.

Martin said he was just wondering because in his first glance at 
the PR, it didn't look like the test suite would be covering a 
lot of cases, unlike for DMD, for example, where the test 
coverage was more complicated. It was quite easy to break the 
test suite there if the implementation was off. But now that he 
had an overview, it seemed fine.

Razvan said that in testing Phobos against D-Scanner, they'd had 
to fix Phobos in some cases, but those were good fixes that made 
the code better.

He said it seemed the consensus was to merge the PR once the test 
suite was passing. Walter said yes and no one objected.



Rikki said that before Luna's work on Objective-C support was 
merged into LDC, she'd spoken with him about it and mentioned the 
need to upstream it into DMD. She'd done a good amount of work on 
it, but there was still more Objective-C support she'd like to 
have in the language.

I asked if upstreaming it to DMD would be an enhancement or 
replacement of the existing stuff. Rikki said it was an 
enhancement.

Walter asked if the PR was large or small. Rikki said Martin had 
been the one reviewing it and deferred to him. Martin said it was 
hard for him to tell. He didn't know what parts of it would be 
upstreamed. As far as he'd understood, it was just for LDC to 
catch up with DMD support, implementing all the stuff Jacob 
Carlborg had implemented years ago for DMD that had never been 
brought over to LDC.

Adam Ruppe had implemented something for the OpenD version of 
LDC. Luna had taken that, reworked it, and upstreamed it. It was 
a preliminary implementation, so surely wasn't 100% perfect. As 
far as he understood, it would be just a few small pieces that 
DMD was missing. He had no idea what those would be.

Walter said when Jacob first implemented it, they'd had a 
discussion. Walter had told him he'd like to see it in its own 
module with hooks into the rest of DMD to minimize disruption. 
With this new stuff, he'd like to continue in this vein to 
minimize the changes to DMD. They should be hooks to functions in 
`objc.d`. There should be almost no functions implementing 
Objective-C stuff in the rest of DMD.

Max said that if he'd been following the PRs and chit-chat 
correctly, he didn't think the DMD aspect would be very big. 
Walter said whether it was big or not, he wanted it to follow the 
same path. He thought it had been a successful approach.

Rikki said he would forward that to Luna.

As a coda to this discussion, Steve wanted to emphasize that it 
was important for DMD and LDC to have the same interface to 
Objective-C so we weren't forced to handle two different 
approaches in code.

Martin said this was mostly in the glue layer, so it was mostly 
about codegen. It wasn't like we could put a piece of code 
upstream in DMD and LDC could just use it. That was the main 
problem. The front end changes were quite minimal. It was mostly 
about codegen, which meant that every D compiler that wanted 
Objective-C support would have to reimplement all that crappy 
stuff. Even GDC.

Steve said his concern was with the interface. If there was a UDA 
in the LDC implementation now that wasn't in DMD, that needed to 
be upstreamed. We shouldn't let them drift apart.

Max said Steve was getting it. We should have any required UDAs 
implemented upstream in DRuntime and then shared. And we should 
be careful to make sure they were exactly the same.



Dennis said he'd seen some issues popping up related to `void*` 
and safety. For example, people wanting the casting of a class 
reference to `void*` to be ` safe`. The question was, should it 
be?

On the one hand, you couldn't really do anything unsafe with a 
`void*`. On the other hand, people were like, "Void pointers are 
kind of low-level C stuff, so they should be  system."

He thought it would be nice if we could nail this down in the 
spec. Did void pointers contain safe values or not? Currently, 
there were some examples in DRuntime showing there were safe ways 
to obtain arbitrary void pointers. So by that logic, either every 
void pointer should be safe, or we should mark functions 
returning `void*` as ` system` even if they were currently 
` trusted`.

Jonathan said passing `void*` around wasn't the issue because you 
were just copying a value. The problem was conversions. You 
wanted to be able to grep and capture all the places you'd 
created a `void*` because you were introducing something that you 
would then have to track down to have any clue that what you were 
dealing with was ` safe`.

Átila asked why. Jonathan said if you were doing anything to cast 
it back, you needed to know where it came from. Átila said that 
was never safe. Jonathan said he knew that, but you needed to be 
able to find the cast *to* `void*` so you could know if what you 
were doing was actually safe. Because you couldn't do anything 
useful with it anyway, except maybe print out the pointer value, 
you didn't really gain much by making it ` safe`.

Steve said it shouldn't be ` safe` because it was mutable. If you 
changed a void pointer, you didn't know what you were changing. 
Átila said you couldn't. How could you change a void pointer? 
Walter said you couldn't change it without converting it again. 
That was unsafe.

Steve said it was hard to think about, but he felt sure there was 
something wrong here if you found a way to modify the pointer 
itself. Walter said you couldn't even increment it in ` safe` 
code. Steve said there were probably ways you could accidentally 
change the type. Átila said there was nothing you could do to it 
without casting, and casting was ` system`. Martin said slicing 
was ` system`, too. He'd just verified it.

Rikki said we should ban `void*` from ` safe` entirely. The only 
thing you could really do was cast it to `size_t` immediately. 
Then you could print it out, compare it, whatever you wanted. 
Martin disagreed, and there were heads shaking in disagreement 
all around.

Martin said the one place he did use `void*` conversion was with 
associative arrays. When he wanted to have the key type be 
dependent on the identity of some object, `void*` did fine. This 
way, he prevented `opCmp` from being used when he was sure he had 
a single reference to an object and just needed to check the 
pointer.

Walter said if anyone could find a case where you could corrupt 
memory with a `void*`, we'd fix it. He didn't know of a case in 
the compiler where that was possible without going into ` system` 
code.

Robert said that after watching everyone discuss this and not 
agreeing, and because he had no idea what was and wasn't 
possible, maybe it shouldn't be in ` safe` code because it seemed 
too complicated to understand in the first place.

He referred to his DConf talk about how ` safe` should be easy. 
You shouldn't have to think whether it was ` safe` or not. He 
didn't know the language inside and out enough to say whether 
something with `void*` was ` safe` or not. That made him feel 
like we shouldn't put it in ` safe`.

Walter said that what `void*` did, and Windows used it this way, 
was it gave you a reference to a memory object that you couldn't 
do anything with. You couldn't break the wall to see what was 
there. It was a handle of a type you didn't know and you couldn't 
do anything with, and it was quite useful for that. You could 
still safely keep track of it. It was fine. It had uses that were 
perfectly ` safe`.

Robert said most things were ` safe` and, he knew this was 
stretching, felt safe. Whenever he saw a `void*`, it didn't feel 
safe. He was inclined to agree with Walter that they were 
technically ` safe`, but as a user, from a user's perspective, 
any time he saw a `void*` he'd be wondering, "Did we check that? 
Is it actually safe?"

Walter said that was a fair argument, but you couldn't do 
anything with it. If you tried to do anything unsafe with it, the 
compiler would kick you on it.

Átila noted that the Pony language had six different reference 
capabilities, which was basically a type of pointer with six 
different kinds. One of them only allowed you to make 
comparisons. That was basically `void*`. This was a pattern that 
was obviously useful.

In his opinion, the way to `void*` was ` safe`. If someone found 
a way to do something with `void*` that corrupted memory, that 
was a bug and we should fix it.

Steve said if you could copy one `void*` to another `void*`, you 
were going to break the invariants of the code surrounding it. A 
good example of this kind of thing was that we didn't allow 
people to set the length of an array without going through an 
interface even though writing an integer was just fine in ` safe` 
code. But doing that was going to break the invariant of the 
array. Similarly, we didn't allow setting the context pointer of 
a delegate in ` safe` code, because you could set it to something 
else.

Átila said it would then be pointing to garbage. You couldn't do 
anything with the `void*` itself. Steve said something else would 
do something with that `void*`. Walter and Átila both said, "No". 
Walter said it was blocked off. Steve said it was blocked off in 
` safe` code. Walter said yes, you could not do anything with a 
`void*` in ` safe` code, that was the whole point.

Steve said that if the only point of `void*` was to compare 
pointers, then yes, but he thought a lot of code expected to cast 
it back to something else. Walter said that would be unsafe.

Steve said to consider a trusted function that assumed a `void*` 
was really a pointer to `T` and so cast it back to `T`. Átila 
said that was unsafe. Steve said you had to cast it back because 
that was the point.

Átila repeated that the way *to* the `void*` was ` safe`. Steve 
said his point was that every ` trusted` function had to assume 
that any `void*` could have been mucked with by ` safe` code 
because you could write to `void*` in ` safe` code.

Átila said the problem was when you cast it back. Steve said the 
point was that you now had to review all of your ` safe` code to 
see if it set that `void*`. Walter said you didn't.

Jonathan said you had to know where the value came from, 
otherwise you couldn't cast it back, even in ` trusted` code. 
Because if you screwed that up, then you had something invalid. 
Walter said when you cast it back, that was unsafe code.

Jonathan agreed, but in order to put ` trusted` on it and 
actually validate it was ` safe`, the user was doing that, not 
the compiler. You still needed to manually verify it to put 
` trusted` on it. You had to be sure where that `void*` came 
from, otherwise you could be casting the wrong thing. Having 
` safe` code able to change the `void*` at all, even if it was 
just pointing it somewhere else, risked it not being what you 
thought it was. Then you'd be doing something invalid with it in 
that ` trusted` code because you couldn't track all the places 
where it was changed.

Walter said Jonathan was right, but said to think about 
allocating memory with `malloc`. You could only do that in 
` system` code and you could only free it in ` system` code. But 
in the meantime, you've passed the pointer into your ` safe` 
code. You assign another value to it and you pass it through a 
` trusted` interface to free it. Then you'd crash your program. 
We couldn't disable that from happening.

If you were passing a `void*` into ` safe` code, you were going 
to have to ensure that it worked. If you were passing it to 
unsafe code and the unsafe code started mucking about with it and 
cast it to something else, that was your problem. That wasn't a 
language problem.

He said it was the same thing Jonathan and Steve were talking 
about. The ` safe` code was correct, but if you misused it inside 
the ` trusted` code that you called, that was your problem.

Steve said ` safe` code had a set of rules that you had to 
follow. You could change integers and do certain things. 
` trusted` code had to assume that all those things could have 
been done. Walter said yes, it was up to the user to make their 
trusted code correct.

Steve said that we had this set of rules to limit what we could 
do in safe code. The mechanism we had to prevent this kind of a 
problem was ` system` variables, which allowed you to say 
something that would normally work in ` safe` code shouldn't, 
because you were going to change it in a way that made it an 
unsafe value. Now you could know the ` trusted` code was invalid. 
The whole idea behind ` safe` code was to reduce the amount of 
code you had to review.

Walter said you had to review ` trusted` code. Steve agreed, but 
said you shouldn't have to review the ` safe` code. Walter said 
you should then have an interface that enforced that you could 
only pass a void pointer to `T` to the trusted code.

Adam said he had a few observations after watching this back and 
forth. First, he thought he understood now why the Windows API 
people aliased `void*` to `HANDLE`: precisely to avoid arguments 
like this.

He said that Walter had been very clear about what `void*` could 
and couldn't do. If we were to just ban `void*` in ` safe` code, 
well now we couldn't use the Windows API in ` safe` code, ever. 
That was a big loss for D right off the bat.

And if you changed a `void*` and passed it back to Windows, did 
you know what it would do? It would blow up. It would give you a 
nice little error code that you could check and move on. That was 
because the Windows API was doing for you what we were talking 
about.

At some point, you had to accept that you were going to do 
something that might have a side effect even in ` safe` code. At 
some point you were going to have to launch the nuclear missiles. 
The only way to write perfectly safe code was to write no code at 
all.

Dennis said he agreed with Robert's assertion that ` safe` code 
should be simple and easy. That was exactly why he wanted us to 
nail down that memory safety was about memory corruption.

If someone said that something should be unsafe, then he wanted 
to ask them to show him how it could corrupt memory. He'd often 
get arguments back about whether it was actually useful in 
` safe` code. That was irrelevant.

It would be really simple if we just said that ` safe` was about 
whether you could corrupt memory or not. Then we wouldn't have 
all of these discussions. But we did keep having them because 
people had something they wanted to do in a part of their code 
base where ` system` code happened to be nearby. And when you got 
into those kinds of arguments, it got really muddy and complex. 
It became a subjective rather than a mathematical matter.

Robert said Dennis was right. He often made the mistake of 
misunderstanding safety as null safety, as Dart had, for 
instance. That was not what ` safe` was. He thought the argument 
Steve made boiled down to that. The only good path forward was to 
explicitly say that ` safe` code was not about null pointer 
safety, but about memory corruption. Those were two different 
things.

Walter said he agreed. Null safety was not a memory safety issue. 
He also wanted to point out that if we prohibited `void*` in 
` safe`, then you could never allocate memory with `malloc` to 
use in safe code. You couldn't guarantee that the reference you 
were passing to a ` trusted free` function was allocated with 
that storage allocator and not something else.

Robert said he wasn't arguing that we shouldn't allow casting to 
`void*` in ` safe`. He was saying we needed to do better 
marketing about what void pointers in ` safe` actually meant. 
Walter agreed.

Ali said we should be protecting from unsafe stuff, but too many 
constraints were always bad. If you were crazy enough to do crazy 
stuff, then yes, you would shoot your foot off. But that didn't 
happen, so we shouldn't go to that level.

There was a digression about defining null safety and Walter's 
experience with Nicklaus Worth's PASCAL, which he said was so 
safe you couldn't actually write any programs in it.

Dennis said that null safety was a separate issue. His goal here 
was to nail down whether ` safe` was just about memory safety, or 
if it was also about protecting from footguns. Because people 
kept having discussions saying something should be ` system` 
wihthout showing how it could actually corrupt memory. He'd seen 
them come up again and again, and he just wanted something he 
could use to put an end to it.

Walter said ` safe` was all about memory safety and not about 
other problems, and Dennis was right that we should make that 
clear.

Rikki said he had his stance on `void*` because it was an entry 
point into memory unsafety. ` safe` should not be an entry to 
memory unsafety, even if it wasn't actually the cause of it.

Dennis said we had ` trusted` and ` safe` interfaces which were 
well defined. We had all the tools you needed to encapsulate your 
handles or void pointers in a struct that had ` system` variables 
or whatever. But in the current specification, you could not 
assume you could dereference a raw `void*` parameter.

I asked Dennis if he had an answer to his question about casting 
to `void*`. He said it seemed not everyone agreed, but with the 
current specification and definition of memory safety, it should 
be allowed and ` safe`.

Martin noted that implicit casts to `void*` were ` safe` for 
every pointer type. He wanted to make sure everyone remembered 
that. What we were talking about now was just explicit casts of 
class references to `void*`.

Átila said it should be ` safe`, because why wouldn't it be?



Rikki thanked Robert for handling the Bugzilla to GitHub 
transition and said there was something we needed to consider. 
Bugzilla was open with its privileges. Anyone could modify the 
fields. That wasn't the case on GitHub.

As an example, he didn't have any rights on the dlang 
organization. He was sure there were other long timers in the 
same boat. We should consider what we were going to do about 
people who should have rights to administrate the Issues, but 
only the Issues.

I asked if admin rights for Issues were separate from everything 
else. I didn't think they were. Adam said GitHub actually 
conflated the PRs and Issues.

Átila asked what concrete problem Rikki was trying to solve. 
Rikki said he needed the rights to administer Issues because that 
was what he'd done in the past on Bugzilla.

I said I didn't think there was anything we needed to change to 
our approach here. We could add people who requested it and who 
we trusted just like we'd always done. And we sometimes had 
invited people in. I didn't have any objection to giving Rikki 
access. No one else did either.

I didn't think we should open it up to anybody and everybody. We 
should handle it on a case-by-case basis as we always had.

Adam told Rikki that we had to be more careful with GitHub Issues 
management, because we were seeing a lot more spam. Because 
GitHub was so popular, there were a lot of bots written to spam 
it and attack it. We couldn't just hand out access like Skittles. 
We needed to know the people we were adding.

This reminded me of a discussion I'd had with Razvan and Dennis 
about cleaning up the GitHub access list. Several people on it 
weren't around anymore. We should probably prune the list. If 
they ever came back and wanted back in, we could add them again. 
I asked if anyone objected to that.

Walter said we should do it. He had taken a couple off the list, 
but he'd been unsure about the rest, so he'd just let it be.

Adam said there were a couple of long-gone people whose names 
kept showing up all the time on PR review requests. He could 
remove them, but he'd rather someone else do it.

I said I could do it.



Our next meeting was a quarterly on January 3rd, 2025. We held 
our next monthly meeting on January 10th.

If you have something you'd like to discuss with us in one of our 
monthly meetings, feel free to reach out and let me know.

Mike Shah <mshah.475 gmail.com> writes:

On Wednesday, 9 April 2025 at 16:42:17 UTC, Mike Parker wrote:
 The D Language Foundation's December 2024 monthly meeting took 
 place on Friday the 13th and lasted around an hour and a half.

 [...]

Thanks for the write up Mike!

I would support continuing DConf Online. Perhaps if DConf online 
is in December it can be advertised at DConf to encourage 
speakers to submit (or perhaps have lightning talks develop into 
longer talks).

aberba <karabutaworld gmail.com> writes:

On Friday, 11 April 2025 at 15:00:58 UTC, Mike Shah wrote:
 On Wednesday, 9 April 2025 at 16:42:17 UTC, Mike Parker wrote:
 The D Language Foundation's December 2024 monthly meeting took 
 place on Friday the 13th and lasted around an hour and a half.

 [...]

 Thanks for the write up Mike!

 I would support continuing DConf Online. Perhaps if DConf 
 online is in December it can be advertised at DConf to 
 encourage speakers to submit (or perhaps have lightning talks 
 develop into longer talks).

+1

Anonymouse <zorael gmail.com> writes:

On Wednesday, 9 April 2025 at 16:42:17 UTC, Mike Parker wrote:
 [...]

Thanks!