Speeding up ELF relocations for store-based systems https://fzakaria.com/2024/05/03/speeding-up-elf-relocations-for-store-based-systems.html

Farid Zakaria’s Blog

Speeding up ELF relocations for store-based systems

Since the introduction of Nix and similar store-based systems such as Guix or Spack, I have been fascinated about finding improvements that take advantage of the new paradigms they introduce. Linux distributions are traditionally dynamic in nature, with shared…

A High-Level Technical Overview of Homomorphic Encryption https://www.jeremykun.com/2024/05/04/fhe-overview/

Math ∩ Programming

A High-Level Technical Overview of Fully Homomorphic Encryption

About two years ago, I switched teams at Google to focus on fully homomorphic encryption (abbreviated FHE, or sometimes HE). Since then I’ve got to work on a lot of interesting projects, learning along the way about post-quantum cryptography, compiler design…

Flying planes in Microsoft Flight Simulator with a JavaScript autopilot (2023) https://pomax.github.io/are-we-flying/

are-we-flying

Flying planes with JavaScript

Writing auto-pilots in JavaScript for MSFS

A History of C Compilers – Part 1: Performance, Portability and Freedom https://thechipletter.substack.com/p/a-history-of-c-compilers-part-1-performance

Substack

Freedom and Portability

Let's talk compilers with part one of a whistle stop tour of their history

查漏补缺

Lancern's Treasure Chest

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今日活动

Lancern's Treasure Chest

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祝各位订户五一假期快乐！✈️✈️✈️

Why SQLite Uses Bytecode https://sqlite.org/draft/whybytecode.html

A leadership crisis in the Nix community https://lwn.net/SubscriberLink/970824/0d89c6d83efad1e0/

Zed Decoded: Rope and SumTree https://zed.dev/blog/zed-decoded-rope-sumtree

zed.dev

Rope & SumTree

From the Zed Blog: In this episode of Zed Decoded, Thorsten asks the founders — Nathan, Max, Antonio — about the data structures at the heart of Zed: Rope and SumTree.

via Cascade Kobayashi

TypeScript: Branded Types https://prosopo.io/articles/typescript-branding/

Prosopo

TypeScript: Branded Types 🔧

How to brand TypeScript types for norminal typing, providing an automated and easy-to-use way of making a type nominal.

Borrow Checking, RC, GC, and the Eleven () Other Memory Safety Approaches https://verdagon.dev/grimoire/grimoire

今日修水管

最近一两周发现家里的水压出奇地低。我住在一栋电梯楼内的三层，照理水压不应该低。刚开始以为是市政供水的问题，但低水压情况持续了好几天没有缓解。遂前往我所在楼层的水表间尝试定位并修复该问题。

在家中水龙头全部关闭的情况下，水表没有走表。这说明家庭管路内没有漏水等情况。

我所在楼层共有四户住户，四根入户水管以并联形式直接连接到单元楼内的一根主供水管道上。在邻居用水时观察邻居的水表走表情况，发现其走表速度明显高于我用水时的走表速度。说明问题出在我家的入户水管上。这一小段入户水管上有且仅有水表以及三个阀门。这四个设备按照从上游到下游排列分别为：阀门 A、阀门 B、阀门 C 和水表。其中阀门 A 和阀门 C 上直接有可供手拧的阀门开关。尝试分别将这两个阀门拧到最大，但问题并没有消失。于是将注意力集中于阀门 B 。

阀门 B 上没有可供手拧的开关，有且仅有一个螺栓和一个压力表。经检查，在不用水时，该压力表显示读数与邻居的压力表读数一致。该读数应该就是单元楼主供水管道内的压力值。在用水时，我家的压力表读数为 0，而在邻居用水时其压力表读数并不为 0 。

上网查阅相关资料可知，阀门 B 是一个减压阀，相关资料指出减压阀上的螺栓可用于调节输出压力。遂翻出扳手等工具相应调节减压阀的螺栓。经过反复调节后，家中的水压恢复了正常。因此问题的原因是我家的减压阀因某种原因被拧了。

2024 年 4 月 Tokyo 会议后一些频道主认为有意思的 C++ 标准提案

P1061R8: Structured Bindings can introduce a Pack
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p1061r8.html

允许结构化绑定引入 pack ：

std::tuple<X, Y, Z> f();

auto [...xs] = f();           // OK
auto [x, ...rest] = f();      // OK
auto [x,y,z, ...rest] = f();  // OK
auto [x, ...rest, z] = f();   // OK

P2034R3: Partially Mutable Lambda Captures
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2034r3.pdf

允许分别将每个 lambda 捕获声明为 mutable 了：

auto a = [mutable x, y]() {
  x = 1;  // OK
  y = 2;  // Error
};

P2135R1: P2055R1: A Relaxed Guide to memory_order_relaxed
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2135r1.pdf

一篇科普性质文章，介绍 C++11 relaxed 内存序的原子操作的 out-of-thin-air 现象以及 read-from-untaken-branch 现象，以及如何在已有程序中识别潜在的相关问题

P2141R2: Aggregates are named tuples
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2141r2.html

让 std::get, std::tuple_element 以及 std::tuple_size 等实现 tuple protocol 的 STL 函数和 type traits 原生支持 aggregate 类型：

struct Foo { int x; double y; std::string z; };

Foo x{1, 2.0, "3"};
std::get<1>(x);  // Evaluate to 2.0
static_assert(std::is_same_v<
  std::string,
  typename std::tuple_element<2, Foo>::type
>);  // OK
static_assert(std::tuple_size<Foo> == 3);  // OK

P2747R2: constexpr placement new
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2747r2.html

让 placement-new 成为 core constant expression

P2748R5: Disallow Binding a Returned Glvalue to a Temporary
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2748r5.html

当函数返回一个引用时，不再允许这个引用绑定到临时对象上，杜绝一类 use-after-free 缺陷：

const int &foo() {
  return 42;  // Ill-formed
}

P2988R4: std::optional<T&>
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p2988r4.pdf

给 std::optional 引入 std::optional<T&> 特化，可以实现用 std::optional 上的 monadic 操作替换一堆空指针判断

逐步氧化起来了

P3166R0: Static Exception Specifications
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p3166r0.html

又要搞大新闻，重新引入了之前被废弃的 throw 声明符，可以用于声明一个函数所能够抛出的所有可能的异常类型：

void throws_nothing() throw();  // Effectively `noexcept`
void throws_a_b() throw(A, B);  // throws_a_b can throw A or B
void throws_any() throw(...);   // throws_any may throw any exception

一个亮点是允许使用 throw(auto) 自动推导函数可能抛出的异常类型集合：

void foo() throw(auto) { /* ... */ }

与老式 throw 声明符的本质区别在于编译器会强制检查异常集合的正确性。如果函数带有 throw 声明符但却可能抛出没有通过 throw 声明符声明的异常，那么程序 ill-formed：

void foo() throw(A) {
  throws_a_b(); // Ill-formed: B is not listed above

  try {
    throws_a_b(); // Ill-formed: B is not caught
  }
  catch (A) {}

  try {
    throws_a_b(); // OK since B will be caught
  }
  catch (A) {}
  catch (B) {}
}

按照这样的设计编译器理论上可以把所有带有 throw 声明符的函数的异常路径算得明明白白，可以开始优化 try-catch 路径了（例如把 throw-catch 直接优化为 goto）。

P3176R0: The Oxford variadic comma
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p3176r0.html

不再允许不带前导逗号的 ellipsis parameter ：

void foo(int ...);  // Ill-formed

Porting a cross-platform GUI application to Rust

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via hacks.mozilla.org via wezm

Mozilla Hacks – the Web developer blog

Porting a cross-platform GUI application to Rust

The Firefox crash reporter has been ported to Rust, with an architecture supporting native cross-platform GUI rendering.