Auto merge of rust-lang#16503 - Veykril:salsa, r=Veykril

Move salsa fork in-tree

No one else is supposed to rely on it anyways, this makes it easier to edit.

Author: bors

Cargo.lock

@@ -70,6 +70,7 @@ proc-macro-srv = { path = "./crates/proc-macro-srv", version = "0.0.0" }
 proc-macro-srv-cli = { path = "./crates/proc-macro-srv-cli", version = "0.0.0" }
 profile = { path = "./crates/profile", version = "0.0.0" }
 project-model = { path = "./crates/project-model", version = "0.0.0" }
+salsa = { path = "./crates/salsa", version = "0.0.0" }
 span = { path = "./crates/span", version = "0.0.0" }
 stdx = { path = "./crates/stdx", version = "0.0.0" }
 syntax = { path = "./crates/syntax", version = "0.0.0" }
@@ -106,22 +107,21 @@ dissimilar = "1.0.7"
 either = "1.9.0"
 expect-test = "1.4.0"
 hashbrown = { version = "0.14", features = [
-    "inline-more",
+  "inline-more",
 ], default-features = false }
 indexmap = "2.1.0"
 itertools = "0.12.0"
 libc = "0.2.150"
 nohash-hasher = "0.2.0"
 rayon = "1.8.0"
-rust-analyzer-salsa = "0.17.0-pre.6"
 rustc-hash = "1.1.0"
 semver = "1.0.14"
 serde = { version = "1.0.192", features = ["derive"] }
 serde_json = "1.0.108"
 smallvec = { version = "1.10.0", features = [
-    "const_new",
-    "union",
-    "const_generics",
+  "const_new",
+  "union",
+  "const_generics",
 ] }
 smol_str = "0.2.1"
 text-size = "1.1.1"

Cargo.toml

@@ -13,7 +13,7 @@ doctest = false
 
 [dependencies]
 la-arena.workspace = true
-rust-analyzer-salsa.workspace = true
+salsa.workspace = true
 rustc-hash.workspace = true
 triomphe.workspace = true
 semver.workspace = true

crates/base-db/Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+name = "salsa"
+version = "0.0.0"
+authors = ["Salsa developers"]
+edition = "2021"
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/salsa-rs/salsa"
+description = "A generic framework for on-demand, incrementalized computation (experimental)"
+
+rust-version.workspace = true
+
+[lib]
+name = "salsa"
+
+[dependencies]
+indexmap = "2.1.0"
+lock_api = "0.4"
+tracing = "0.1"
+parking_lot = "0.12.1"
+rustc-hash = "1.0"
+smallvec = "1.0.0"
+oorandom = "11"
+triomphe = "0.1.11"
+
+salsa-macros = { version = "0.0.0", path = "salsa-macros" }
+
+[dev-dependencies]
+linked-hash-map = "0.5.6"
+rand = "0.8.5"
+test-log = "0.2.14"
+expect-test = "1.4.0"
+dissimilar = "1.0.7"
+
+[lints]
+workspace = true

crates/salsa/Cargo.toml

@@ -0,0 +1,34 @@
+# Frequently asked questions
+
+## Why is it called salsa?
+
+I like salsa! Don't you?! Well, ok, there's a bit more to it. The
+underlying algorithm for figuring out which bits of code need to be
+re-executed after any given change is based on the algorithm used in
+rustc. Michael Woerister and I first described the rustc algorithm in
+terms of two colors, red and green, and hence we called it the
+"red-green algorithm". This made me think of the New Mexico State
+Question --- ["Red or green?"][nm] --- which refers to chile
+(salsa). Although this version no longer uses colors (we borrowed
+revision counters from Glimmer, instead), I still like the name.
+
+[nm]: https://www.sos.state.nm.us/about-new-mexico/state-question/
+
+## What is the relationship between salsa and an Entity-Component System (ECS)?
+
+You may have noticed that Salsa "feels" a lot like an ECS in some
+ways. That's true -- Salsa's queries are a bit like *components* (and
+the keys to the queries are a bit like *entities*). But there is one
+big difference: **ECS is -- at its heart -- a mutable system**. You
+can get or set a component of some entity whenever you like. In
+contrast, salsa's queries **define "derived values" via pure
+computations**.
+
+Partly as a consequence, ECS doesn't handle incremental updates for
+you. When you update some component of some entity, you have to ensure
+that other entities' components are updated appropriately.
+
+Finally, ECS offers interesting metadata and "aspect-like" facilities,
+such as iterating over all entities that share certain components.
+Salsa has no analogue to that.
+