Using cppfront with Meson

Recently Herb Sutter published cppfront, which is an attempt to create C++ a new syntax to fix many issues that can't be changed in existing C++ because of backwards compatibility. Like with the original cfront compiler, cppfront works by parsing the "new syntax" C++ and transpiling it to "classic" C++, which is then compiled in the usual way. These kinds of source generators are fairly common (it is basically how Protobuf et al work) so let's look at how to add support for this in Meson. We are also going to download and build the cppfront compiler transparently.

Building the compiler

The first thing we need to do is to add Meson build definitions for cppfront. It's basically this one file:

project('cppfront', 'cpp', default_options: ['cpp_std=c++20'])

cppfront = executable('cppfront', 'source/cppfront.cpp',
  override_options: ['optimization=2'])

meson.override_find_program('cppfront', cppfront)
cpp2_dep = declare_dependency(include_directories: 'include')

The compiler itself is in a single source file so building it is simple. The only thing to note is that we override settings so it is always built with optimizations enabled. This is acceptable for this particular case because the end result is not used for development, only consumption. The more important bits for integration purposes are the last two lines where we define that from now on whenever someone does a find_program('cppfront') Meson does not do a system lookup for the binary but instead returns the just-built executable object instead. Code generated by cppfront requires a small amount of helper functionality, which is provided as a header-only library. The last line defines a dependency object that carries this information (basically just the include directory).

Building the program

The actual program is just a helloworld. The Meson definition needed to build it is this:

project('cpp2hello', 'cpp',

    default_options: ['cpp_std=c++20'])

cpp2_dep = dependency('cpp2')

cppfront = find_program('cppfront')

g = generator(cppfront,

  output: '@BASENAME@.cpp',

  arguments: ['@INPUT@', '-o', '@OUTPUT@']

  )

sources = g.process('sampleprog.cpp2')

executable('sampleprog', sources,

   dependencies: [cpp2_dep])

That's a bit more code but still fairly straightforward. First we get the cppfront program and the corresponding dependency object. Then we create a generator that translates cpp2 files to cpp files, give it some input and compile the result.

Gluing it all together

Each one of these is its own isolated repo (available here and here respectively). The simple thing would have been to put both of these in the same repository but that is very inconvenient. Instead we want to write the compiler setup once and use it from any other project. Thus we need some way of telling our app repository where to get the compiler. This is achieved with a wrap file:

[wrap-git]
directory=cppfront
url=https://github.com/jpakkane/cppfront
revision=main

[provide]
cpp2 = cpp2_dep
program_names = cppfront

Placing this in the consuming project's subprojects directory is all it takes. When you start the build and try to look up either the dependency or the executable name, Meson will see that they are provided by the referenced repo and will clone, configure and build it automatically:

The Meson build system

Version: 0.63.99

Source dir: /home/jpakkane/src/cpp2meson

Build dir: /home/jpakkane/src/cpp2meson/build

Build type: native build

Project name: cpp2hello

Project version: undefined

C++ compiler for the host machine: ccache c++ (gcc 11.2.0 "c++ (Ubuntu 11.2.0-19ubuntu1) 11.2.0")

C++ linker for the host machine: c++ ld.bfd 2.38

Host machine cpu family: x86_64

Host machine cpu: x86_64

Found pkg-config: /usr/bin/pkg-config (0.29.2)

Found CMake: /usr/bin/cmake (3.22.1)

Run-time dependency cpp2 found: NO (tried pkgconfig and cmake)

Looking for a fallback subproject for the dependency cpp2

Executing subproject cppfront 

cppfront| Project name: cppfront

cppfront| Project version: undefined

cppfront| C++ compiler for the host machine: ccache c++ (gcc 11.2.0 "c++ (Ubuntu 11.2.0-19ubuntu1) 11.2.0")

cppfront| C++ linker for the host machine: c++ ld.bfd 2.38

cppfront| Build targets in project: 1

cppfront| Subproject cppfront finished.

Dependency cpp2 from subproject subprojects/cppfront found: YES undefined

Program cppfront found: YES (overridden)

Build targets in project: 2

As you can tell from the logs, Meson first tries to find the dependencies from the system and only after it fails does it try to download them from the net. (This behaviour can be altered.) Now the code can be built and the end result run:

$ build/sampleprog

Cpp2 compilation is working.

The code has only been tested with GCC but in theory it should work with Clang and VS too.

"Why is it that package managers are unnecessarily hard?" — or are they?

At the moment the top rated post in In the C++ subreddit is Why is it that package managers are unnecessarily hard?. The poster wants to create an application that uses fmt and SDL2. After writing a lengthy and complicated (for the task) build file, installing a package manager, integrating the two and then trying to build their code the end result fails leaving only incomprehensible error messages in its wake.

The poster is understandably frustrated about all this and asks a reasonable question about the state of package management. The obvious follow-up question, then, would be whether they need to be hard. Let's try to answer that by implementing the thing they were trying to do from absolute scratch using Meson. For extra challenge we'll do it on Windows to be entirely sure we are not using any external dependency providers.

Prerequisites

• A fresh Windows install with Visual Studio
• No vcpkg, Conan or any other third party package manager installed (more strictly, they can be installed, just ensure that they are not used)
• Meson installed so that you can run it just by typing meson from a VS dev tools command prompt (if you set it up so that you run python meson.py or meson.py, adjust the commands below accordingly)
• Ninja installed in the same way (you can also use the VS solution generator if you prefer in which case this is not needed)

The steps required

Create a subdirectory to hold source files.

Create a meson.build file in said dir with the following contents.

project('deptest', 'cpp',
    default_options: ['default_library=static',
                      'cpp_std=c++latest'])
fmt_dep = dependency('fmt')
sdl2_dep = dependency('sdl2')
executable('deptest', 'deptest.cpp',
   dependencies: [sdl2_dep, fmt_dep])

Create a deptest.cpp file in the same dir with the following contents:

#include<fmt/core.h>
#include<SDL.h>

int main(int, char**) {
    if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO) != 0) {
        fmt::print("Unable to initialize SDL: {}", SDL_GetError());
        return 1;
    }
    SDL_version sdlver;
    SDL_GetVersion(&sdlver);
    fmt::print("Currently using SDL version {}.{}.{}.",
               sdlver.major, sdlver.minor, sdlver.patch);
    return 0;
}

Start a Visual Studio x64 dev tools command prompt, cd into the source directory and run the following commands.

mkdir subprojects
meson wrap install fmt
meson wrap install sdl2
meson build
ninja -C build

build\deptest

This is all you need to do to get the following output:

Currently using SDL version 2.24.0.

Most people would probably agree that this is not "unnecessarily hard". Some might even call it easy.

Diving deeper into custom PDF and epub generation

In a previous blog post I looked into converting a custom markup text format into "proper" PDF and epub documents. The format at the time was very simple and could not do even simple things like italic text. At the time it was ok, but as time went on it seemed a bit unsatisfactory.

Ergo, here is a sample input document:

# Demonstration document

This document is a collection of sample paragraphs that demonstrate

the different features available, like /italic text/, *bold text* and

even |Small Caps text|. All of Unicode is supported: ", », “, ”.

The previous paragraph was not indented as it is the first one following a section title. This one is indented. Immediately after this paragraph the input document will have a scene break token. It is not printed, but will cause vertical white space to be added. The

paragraph following this one will also not be indented.

#s

A new scene has now started. To finish things off, here is a

standalone code block:

```code

#include<something.h>

/* Cool stuff here */

```

This is "Markdown-like" but specifically not Markdown because novel typesetting has requirements that can't easily be retrofit in Markdown. When processed this will yield the following output:

Links to generated documents: PDF, epub. The code can be found on Github.

A look in the code

An old saying goes that that the natural data structure for any problem is an array and if it is not, then change the problem so that it is. This turned out very much to be the case in this problem. The document is an array of variants (section, paragraph, scene change etc). Text is an array of words (split at whitespace) which get processed into output, which is an array of formatted lines. Each line is an array of formatted words.

For computing the global chapter justification and final PDF it turned out that we need to be able to render each word in its final formatted form, and also hyphenated sub-forms, in isolation. This means that the elementary data structure is this:

struct EnrichedWord {
    std::string text;
    std::vector<HyphenPoint> hyphen_points;
    std::vector<FormattingChange> format;
    StyleStack start_style;
};

This is "pure data" and fully self-contained. The fields are obvious: text has the actual text in UTF-8. hyphen_points lists all points where the word can be hyphenated and how. For example if you split the word "monotonic" in the middle you'd need to add a hyphen to the output but if you split the hypothetical combination word "meta–avatar" in the middle you should not add a hyphen, because there is already an en-dash at the end. format contains all points within the word where styling changes (e.g. italic starts or ends). start_style is the only trickier one. It lists all styles (italic, bold, etc) that are "active" at the start of the word and the order in which they have been declared. Since formatting tags can't be nested, this is needed to compute and validate style changes within the word.

Given an array of these enriched words the code computes another array of all possible points where the text stream can be split, both within and between words. The output of this algorithm is then yet another array. It contains all the split points. With this the final output can be created fairly easily: each output line is the text between split points n and n+1.

The one major missing typographical feature missing is widow and orphan control. The code merely splits the page whenever it is full. Interestingly it turns out that doing this properly is done with the same algorithm as paragraph justification. The difference is that the penalty terms are things like "widow existence" and "adjacent page height imbalance".

But that, as they say, is another story. Which I have not written yet and might not do for a while because there are other fruit to fry.

Questions to ask a prospective employer during a job interview

Question: Do developers in your organization have full admin rights on their own computer?

Rationale: While blocking admin rights might make sense for regular office workers it is a massive hindrance for software developers. They do need admin access for many things and not giving it to them is a direct productivity hit. You might also note that Google does give all their developers root access to their own dev machines and see how they respond.

Question: Are developers free to choose and install the operating system on their development machines? If yes, can you do all administrative and bureaucracy task from "non-official" operating systems?

Rationale: Most software projects nowadays deal with Linux somehow and many people are thus more productive (and happier) if they can use a Linux desktop for their development. If the company mandates the use of "IT-approved" Windows install where 50% of all CPU time is spent on virus scanners and the like, productivity takes a big hit. There are also some web services that either just don't work on Linux or are a massive pain to use if they do (the web UI of Outlook being a major guilty party here).

Question: How long does it take to run the CI for new merge requests?

Rationale: Anything under 10 minutes is good. Anything over 30 minutes is unacceptably slow. Too slow of a CI means that instead of submitting small, isolated commits people start aggregating many changes into a small number of mammoth commits because it is the only way to get things done. This causes the code quality to plummet.

Question: Suppose we find a simple error, like a typo in a log message. Could you explain the process one needs to follow to get that fixed and how long does it approximately take? Explicitly list out all the people in the organization that are needed to authorize said change.

Rationale: The answer to this should be very similar to the one above: make the commit, submit for review, get ack, merge. It should be done in minutes. Sometimes that is not the case. Maybe you are not allowed to work on issues that don't have an associated ticket or that are not pre-approved for the current sprint. Maybe you need to first create a ticket for the issue. Maybe you first need to get manager approval to create said ticket (You laugh, but these processes actually exist. No, I'm not kidding.). If their reply contains phrases like "you obtain approval from X", demand details: how do you apply for approval, who does it, how long is it expected to take, what happens if your request is rejected, and so on. If the total time is measured in days, draw your own conclusions and act accordingly

Question: Suppose that I need to purchase some low-cost device like a USB hub for development work. Could you explain the procedure needed to get that done? 

Rationale: The answer you want is either "go to a store of your choice, buy what you need and send the receipt to person X" or possibly "send a link to person X and it will be on your desk (or delivered home) within two days". Needing to get approval from your immediate manager is sort of ok, but needing to go any higher or sideways in the org chart is a red flag and so is needing to wait more than a few days regardless of the reason.

Question: Could you explain the exact steps needed to get the code built?

Rationale: The steps should be "do a git clone, run the build system in the standard way, compile, done". Having a script that you can run that sets up the environment is also fine. Having a short wiki page with the instructions is tolerable. Having a long wiki page with the instructions is bad. "Try compilng and when issues arise ask on slack/teams/discord/water cooler/etc" is very bad.

Question: Can you build the code and run tests on the local machine as if it was a standard desktop application?

Rationale: For some reason corporations love creating massive build clusters and the like for their products (which is fine) and then make it impossible to build the code in isolation (which is not fine). Being able to build the project on your own machine is pretty much mandatory because if you can't build locally then e.g. IDE autocompletions does not work because there is no working compile_commands.json.

This even applies for most embedded projects. A well designed embedded project can be configured so that most code can be built and tested on the host compiler and only the hardware-touching bits need cross compilation. This obviously does not cover all cases, such as writing very low level firmware that is mostly assembly. You have to use your own judgement here.

Question: Does this team or any of the related teams have a person who actively rejects proposals to improve the code base?

Rationale: A common dysfunction in existing organizations is to have a "big fish in a small pond" developer, one that has been working on said code for a long time but which has not looked at what has been happening in the software development landscape in general. They will typically hard reject all attempts to improve the code and related processes to match current best practices. They typically use phrases like "I don't think that would improve anything", "That can't work (no further reasoning given)" and the ever popular "but we already have [implementation X, usually terrible] and it works". In extreme cases if their opinions are challenged they resort to personal attacks. Because said person is the only person who truly understands the code, management is unwilling to reprimand them out of fear that they might leave.

Out of all the questions in this list, this one is the most crucial. Having to work with such a person is a miserable experience and typically a major factor in employee churn. This is also the question that prospective employers are most likely to flat out lie to you because they know that if they admit to this, they can't hire anyone. If you are interviewing with a manager, then they might not even know that they have such a person in their team. The only reliable way to know this is to talk with actual engineers after they have had several beers. This is hard to organize before getting hired.

Question: How many different IT support organizations do you have. Where are they physically located?

Rationale: The only really acceptable answer is "in the same country as your team" (There are exceptions, such as being the only employee in a given country working 100% remote). Any other answer means that support requests take forever to get done and are a direct and massive drain on your productivity. The reason for this inefficiency is that if you have your "own" support then you can communicate with each other like regular human beings. If they are physically separated then you just became just another faceless person in a never ending ticketing queue somewhere and things that should take 15 minutes take weeks (these people typically need to serve many organisations in different countries and are chronically overworked).

The situation is even worse if the IT support is moved to physically distant location and even worse if it is bought as a service from a different corporation. A typical case is that a corporation in Europe or USA outsources all their IT support to India or Bangladesh. This is problematic, not because people in said countries are not good at their jobs (I've never met them so I can't really say) but because these transfers are always done to minimize costs. Thus a core part of the organization's engineering productivity is tied to an organisation that is 5-10 time zones away, made the cheapest offer and over which you can't even exert any organizational pressure over should it be needed. This is not a recipe for success. If there are more than one such external companies within the organization, failure is almost guaranteed.

Question: Suppose the team needs to start a new web service like a private Gitlab, add new type of CI to the testing pipeline or something similar. Could you explain the exact steps needed to get it fully operational? Please list all people who need to do work to make this happen (including just giving authorization), and time estimates for each individual step.

Rationale: This follows directly from the above. Any answer that has more than one manager and takes more than a day or two is a red flag.

Question: Please list all the ways you are monitoring your employees during work hours. For example state whether you have a mandatory web proxy that everyone must use and enumerate all pieces of security and tracking software you have installed on employees' computers. Do you require all employees to assign all work hours to projects? If yes, what granularity? If the granularity is less than 1 hour, does your work sheet contain an entry for "entering data into work hour enumeration sheet"?

Rationale: This one should be fairly obvious, but note that you are unlikely to get a straight answer.

Looking at LibreOffice's Windows installer

There has long been a desire to get rid of Cygwin as a build dependency on LibreOffice. In addition to building dependencies it is also used to create the Windows MSI installer. Due to reasons I don't remember any more I chose to look into replacing just that bit with some modern tooling. This is the tragedy that followed.

The first step to replacing something old is to determine what and how the old system works. Given that it is an installer one would expect it to use WiX, NSIS or maybe even some less know installer tool. But of course you already guessed that's not going to be the case. After sufficient amounts of digging you can discover that the installer is invoked by this (1600+ line) Perl script. It imports 50+ other internal Perl modules. This is not going to be a fun day.

Eventually you stumble upon this file and uncover the nasty truth. The installer works by manually building a CAB file with makecab.exe and Perl. Or, at least, that is what I think it does. With Perl you can never be sure. It might even be dead code that someone forgot to delete. So I asked from my LO acquaintances if that is how it actually works. The answer? "Nobody knows. It came from somewhere and was hooked to the build and nobody has touched it since."

When the going gets tough, the tough starts compiling dependencies from scratch

In order to see if that is actually what is happening, we need to to be able to run it and see what it does. For that we need to first compile LO. This is surprisingly simple, there is a script that does almost all of the gnarly bits needed to set up the environment. So then you just run it? Of course you don't.

When you start the build, first things seem to work fine, but then one of the dependencies misdetects the build environment as mingw rather than cygwin and then promptly fails to build. Web searching finds this email thread which says that the issue has been fixed. It is not.

I don't even have mingw installed on this machine.

It still detects the environment as mingw.

Then I uninstalled win-git and everything that could possibly be interpreted as mingw.

It still detects the environment as mingw.

Then I edited the master Makefile to pass an explicit environment flag to the subproject's configure invocation.

It still detects the environment as mingw.

Yes, I did delete all cached state I could think of between each step. It did not help.

I tried everything I could and eventually had to give up. I could not make LO compile on Windows. Back to the old drawing board.

When unzipping kills your machine

What I actually wanted to test was to build the source code, take the output directory and then pass that to the msicreator program that converts standalone directories to MSI installers using WiX. This is difficult to do if you can't even generate the output files in the first place. But there is a way to cheat.

We can take the existing LO installer, tell the Windows installer to just extract the files in a standalone directory and then use that as the input data. So then I did the extraction and it crashed Windows hard. It brought up the crash screen and the bottom half of it had garbled graphics. Which is an impressive achievement for what is effectively the same operation as unpacking a zip file. Then it did it again. The third time I had my phone camera ready to take a picture but that time it succeeded. Obviously.

After fixing a few bugs in msireator and the like I could eventually build my own LibreOffice installer. I don't know if it is functionally equivalent but at least most of the work should be there. So, assuming that you can do the equivalent of DESTDIR=/foo make install with LO on Windows then you should be able to replace the unmaintained multi-thousand line Perlthulhu with msicreator and something like this:

{

    "upgrade_guid": "SOME-GUID-HERE",

    "version": "7.4.0",

    "product_name": "LibreOffice",

    "manufacturer": "LibreOffice something something",

    "name": "LibreOffice",

    "name_base": "libreoffice",

    "comments": "This is a comment.",

    "installdir": "printerdir",

    "license_file": "license.rtf",

    "need_msvcrt": true,

    "parts": [

        {

         "id": "MainProgram",

         "title": "The Program",

         "description": "The main program",

         "absent": "disallow",

         "staged_dir": "destdir"

        }

    ]

}

In practice it probably won't be this simple, because it never is.

Random things on designing a text format for books

In previous blog posts there was some talk about implementing a simple system that generates books (both PDF and ebook) from plain text input files. The main question for that is what the input format should be. Currently there are basically two established formats: LaTeX and Markdown. The former is especially good if the book has a lot of figures, cross references, indexes and all that. The latter is commonly used in most modern web systems but it is more suitable to specifying text in the "web page" style as opposed to "split aesthetically over pages".

The obvious solution when faced with this issue is to design your own file format that fits your needs perfectly. I did not do that, but instead I did think about the issue and did some research and thinking. This is the outcome of that. It is not a finished product, you can think of instead as a grouping of unrelated things and design requirements that you'd need to deal with when creating such a file format.

Goals

The file format should be used to create traditional novel like Lord of the Rings and The Hitch-Hiker's Guide to the Galaxy. The output will be a "single flow" of text separated by chapter headings and the like. There needs to be support for different paragraph styles for printing things like poems, telegraphs or computer printouts in different fonts and indents.

The input files must be UTF-8 plain text in a format that works natively with revision control systems.

Supporting pictures and illustrations should be possible.

You need to be able to create both press-ready PDFs and epubs directly from the input files without having to reformat the text with something like Scribus.

Don't have styling information inside the input files. Those should be defined elsewhere, for example when generating the epub, all styling should come from a CSS file that the end user writes by hand. The input text should be as "syntax-only" as possible.

Writing HTML or XML style tags is right out.

Specifying formatting inline

Both LaTeX and Markdown specify their style information inline. This seems like a reasonable approach that people are used to. In fact I have seen Word documents written by professional proofreaders that do not use Word's styling at all but instead type Markdown-style formatting tokens inside Word documents.

The main difference between LaTeX and Markdown is that the former is verbose whereas the latter is, well, not as simple as you'd expect. The most common emphasis style is italic. The LaTeX way of doing it is to write \emph{italic} whereas Markdown requires it to be written as _italic_. This is one of the main annoying things about the LaTeX format, you need to keep typing that emph (or create a macro for it) and it takes up a lot of space in your text. Having a shorthand for common operations, like Markdown does, seems like an usability win. Typing \longcommand for functionality that is only used rarely is ok.

These formatting tokens have their own set of problems. Here's something you can try in any web site that supports Markdown formatting (I used Github here). Write the same word twice: one time so that the middle of the word has styling tokens and a second time so that the entire word is emphasized.

Then click on the preview tab.

Whoops. One of the two of these has unexpected formatting. Some web editors even get this wrong. If you use a graphical preview widget and emphasize the middle of the word using ctrl-i, the editor shows it as emphasized but if you click on the text tab and then return to the preview tab it shows the underscore characters rather than italic text.

This might lead you to think that underscores within words (i.e. sequences of characters separated by whitespace) are ignored. So let's test that.

This is a simple test with three different cases. Let's look at the outcome.

Our hypothesis turned out incorrect. There are special cases where underscores within words are considered styling information and others where they should be treated as characters. It is left as an exercise to the reader to 1) determine when that is and 2) what is the rendering difference between the two lower lines in the image (there is one).

Fair enough. Surely the same applies for other formatting as well.

This turns into:

Nope, behavioural difference again! But what if you use double underscores?

Okay, looking good. Surely that will work:

Nope. So what can we learn from this? Basically that in-band signaling is error prone and you typically should avoid it because it will come back and bite you in the ass. Since the file format is UTF-8 we could sacrifice some characters outside basic ASCII for this use but then you get into the problem of needing to type them out with unusual keyboard combinations (or configure your editor to write them out when typing ctrl-i or ctrl-b).

Small caps

Small caps letters are often used in high quality typography. In LaTeX you get them with the \textsc command. Markdown does not support small caps at all. There are several discussion threads that talk about adding support for it to Markdown. To save you time, here is a condensed version of pretty much all of them:

"Can we add small caps to Markdown?"

"No, you don't need them."

"Yes I do."

"No you don't."

And so on. Small caps might be important enough to warrant its own formatting character as discussed in the previous chapter and the implementation would have the same issues.

The dialogue clash

There are many different ways of laying out dialogue. Quotation marks are the most common but starting a paragraph with a dash is also used (in Finnish at least, this might be culture dependent). Like so:

– Use the Force Luke, said Obi-Wan.

Thus it would seem useful to format all paragraphs that start with a dash character as dialogue. In this example the actual formatting used an en-dash. If you want to go the Markdown way this is problematic, because it specifies that lines starting with dashes turn into bulleted lists:

• Use the Force Luke, said Obi-Wan.

These are both useful things and you'd probably want to support both, even though the latter is not very common in story-oriented books. Which one should use the starting dash? I don't have a good answer.

Making decision without all the information is tricky, a case study

In a recent blog post, Michal Catanzaro wrote about choosing proper configurations for your build, especially the buildtype attribute. As noted in the text, Meson's build type setup is not the greatest in the world., so I figured I'd write why that is, what would a better design look like and why we don't use that (and probably won't for the foreseeable future).

The concept of build types was copied almost directly from CMake. The main thing that they do is to set compiler flags like -g and -O2. Quite early in the development process of Meson I planned on adding top level options for debug info and optimization but the actual implementation for those was done much later. I copied the build types and flags almost directly except for build types RelWithDebInfo and Release. Having these two as separate build types did not make sense to me, because you always need debug info for releases. If you don't have it, you can't debug crash dumps coming from users. Thus I renamed them to debugoptimized and release.

So far so good, except there was one major piece of information I was missing. The word "debug" has two different meaning. On most platforms it means "debug info" but on Windows (or, specifically, with the MSVC toolchain) "debug" means a special build type that uses the "debug runtime" that has additional runtime checks that are useful during development. More info can be found e.g. here. This made the word "debug" doubly problematic. Not only do people on Windows want it to refer to the debug runtime but then some (but not all) people on Linux think that "debugoptimized" means that it should only be used during development. Originally that was not the case, it was supposed to mean "build a binary with the default optimizations and debug info". What I originally wanted was that distros would build packages with buildtype set to debugoptimized as opposed to living in the roaring 90s, passing a random collection of flags via CFLAGS and hoping for the best.

How it should have been done?

With the benefit of hindsight a better design is fairly easy to see. Given that Meson already has toggles for all individual bits, buildtype should describe the "intent", that is, what the end result will be used for. Its possible values should have the following:

• development
• releaseperf (maximize performance)
• releasesize (minimize size)

It might also contain the following:

• distro (when building distro packages)
• fuzzing

Note that the word "debug" does not appear. This is intentional, all words are chosen so that they are unambiguous. If they are not, then they would need to be changed. The value of this option would be orthogonal to other flags. For example you might want to have a build type that minimizes build size but still uses -O2, because sometimes it produces smaller code than -Os or -Oz. Suppose you have two implementations of some algorithm: one that has maximal performance and another that yields less code. With this setup you could select between the two based on what the end result will be used rather than trying to guess it from optimization flags. (Some of this you can already do, but due to issues listed in Michael's blog it is not as simple.)

Can we switch to this model?

This is very difficult due to backwards compatibility. There are a ton of existing projects out there that depend on the way things are currently set up and breaking them would lead to a ton of unhappy users. If Meson had only a few dozen users I would have done this change already rather than writing this blog post.