Properly handle different defaults for severity of lints

Previously all lints were assumed to be `#[warn]`, and we had a hand-coded list of `#[allow]` exceptions. Now the severity is autogenerated from rustdoc output.

Also support lints that change status between editions, and the `warnings` lint group.

src/tools/rust-analyzer/Cargo.lock

@@ -389,6 +389,10 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9bda8e21c04aca2ae33ffc2fd8c23134f3cac46db123ba97bd9d3f3b8a4a85e1"
 
+[[package]]
+name = "edition"
+version = "0.0.0"
+
 [[package]]
 name = "either"
 version = "1.13.0"
@@ -1266,6 +1270,7 @@ name = "parser"
 version = "0.0.0"
 dependencies = [
  "drop_bomb",
+ "edition",
  "expect-test",
  "limit",
  "ra-ap-rustc_lexer",
@@ -2662,6 +2667,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "directories",
+ "edition",
  "either",
  "flate2",
  "itertools",

src/tools/rust-analyzer/Cargo.toml

@@ -83,6 +83,7 @@ toolchain = { path = "./crates/toolchain", version = "0.0.0" }
 tt = { path = "./crates/tt", version = "0.0.0" }
 vfs-notify = { path = "./crates/vfs-notify", version = "0.0.0" }
 vfs = { path = "./crates/vfs", version = "0.0.0" }
+edition = { path = "./crates/edition", version = "0.0.0" }
 
 ra-ap-rustc_lexer = { version = "0.85", default-features = false }
 ra-ap-rustc_parse_format = { version = "0.85", default-features = false }

src/tools/rust-analyzer/crates/edition/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "edition"
+version = "0.0.0"
+rust-version.workspace = true
+edition.workspace = true
+license.workspace = true
+authors.workspace = true
+repository.workspace = true
+
+[dependencies]
+
+[lints]
+workspace = true

src/tools/rust-analyzer/crates/parser/src/edition.rs → src/tools/rust-analyzer/crates/edition/src/lib.rs

@@ -1,6 +1,5 @@
 //! The edition of the Rust language used in a crate.
-// Ideally this would be defined in the span crate, but the dependency chain is all over the place
-// wrt to span, parser and syntax.
+// This should live in a separate crate because we use it in both actual code and codegen.
 use std::fmt;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]

src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/lint.rs

@@ -11,7 +11,7 @@ pub(super) fn complete_lint(
     existing_lints: &[ast::Path],
     lints_completions: &[Lint],
 ) {
-    for &Lint { label, description } in lints_completions {
+    for &Lint { label, description, .. } in lints_completions {
         let (qual, name) = {
             // FIXME: change `Lint`'s label to not store a path in it but split the prefix off instead?
             let mut parts = label.split("::");