Rollup merge of #135391 - jieyouxu:conditional-tracing, r=onur-ozkan

bootstrap: Implement conditional `tracing` infra

Add a conditional `tracing` setup that is gated behind `BOOTSTRAP_TRACING` env var. This `tracing` infra is implemented by:

- Introducing an optional `tracing` cargo feature in bootstrap.
- Added optional `tracing*` dependencies which are gated behind the `tracing` cargo feature.
- When `BOOTSTRAP_TRACING` is set, `bootstrap.py` will build bootstrap with `--features=tracing`.

There is a small trick here to share `BOOTSTRAP_TRACING` env var without having to add a separate env var:

- `BOOTSTRAP_TRACING=1` is not a registered `tracing` filter target, so that can be used to enable the `tracing` cargo feature yet not actually enable any tracing logs (useful for editor r-a setups without actually outputting any tracing logs).
- `BOOTSTRAP_TRACING=TRACE` and such are actually valid `tracing` filters, but that sets `BOOTSTRAP_TRACING` anyway.

Example usage: #135299 (that experimental PR is not conditionally gated)
This PR is intentionally kept minimal to focus on the infra itself. To get actual mileage, instrumentations will need to be added to individual `Step`s and such.

r? `@onur-ozkan` (or reroll)

Author: jhpratt

src/bootstrap/Cargo.lock

@@ -58,6 +58,9 @@ dependencies = [
  "tar",
  "termcolor",
  "toml",
+ "tracing",
+ "tracing-subscriber",
+ "tracing-tree",
  "walkdir",
  "windows 0.52.0",
  "xz2",
@@ -70,7 +73,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40723b8fb387abc38f4f4a37c09073622e41dd12327033091ef8950659e6dc0c"
 dependencies = [
  "memchr",
- "regex-automata",
+ "regex-automata 0.4.9",
  "serde",
 ]
 
@@ -271,8 +274,8 @@ dependencies = [
  "aho-corasick",
  "bstr",
  "log",
- "regex-automata",
- "regex-syntax",
+ "regex-automata 0.4.9",
+ "regex-syntax 0.8.5",
 ]
 
 [[package]]
@@ -300,7 +303,7 @@ dependencies = [
  "globset",
  "log",
  "memchr",
- "regex-automata",
+ "regex-automata 0.4.9",
  "same-file",
  "walkdir",
  "winapi-util",
@@ -322,6 +325,12 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.167"
@@ -362,6 +371,15 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "matchers"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8263075bb86c5a1b1427b5ae862e8889656f126e9f77c484496e8b47cf5c5558"
+dependencies = [
+ "regex-automata 0.1.10",
+]
+
 [[package]]
 name = "memchr"
 version = "2.7.4"
@@ -377,6 +395,25 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
+
+[[package]]
+name = "nu-ansi-term"
+version = "0.50.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d4a28e057d01f97e61255210fcff094d74ed0466038633e95017f5beb68e4399"
+dependencies = [
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "object"
 version = "0.36.5"
@@ -386,6 +423,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.20.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
+
 [[package]]
 name = "opener"
 version = "0.5.2"
@@ -396,6 +439,18 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
+
 [[package]]
 name = "pkg-config"
 version = "0.3.31"
@@ -439,6 +494,27 @@ dependencies = [
  "bitflags",
 ]
 
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata 0.4.9",
+ "regex-syntax 0.8.5",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c230d73fb8d8c1b9c0b3135c5142a8acee3a0558fb8db5cf1cb65f8d7862132"
+dependencies = [
+ "regex-syntax 0.6.29",
+]
+
 [[package]]
 name = "regex-automata"
 version = "0.4.9"
@@ -447,9 +523,15 @@ checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
 dependencies = [
  "aho-corasick",
  "memchr",
- "regex-syntax",
+ "regex-syntax 0.8.5",
 ]
 
+[[package]]
+name = "regex-syntax"
+version = "0.6.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f162c6dd7b008981e4d40210aca20b4bd0f9b60ca9271061b07f78537722f2e1"
+
 [[package]]
 name = "regex-syntax"
 version = "0.8.5"
@@ -539,12 +621,27 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
+[[package]]
+name = "smallvec"
+version = "1.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
+
 [[package]]
 name = "syn"
 version = "2.0.87"
@@ -589,6 +686,16 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "thread_local"
+version = "1.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b9ef9bad013ada3808854ceac7b46812a6465ba368859a37e2100283d2d719c"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+]
+
 [[package]]
 name = "toml"
 version = "0.5.11"
@@ -598,6 +705,79 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "tracing"
+version = "0.1.41"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "784e0ac535deb450455cbfa28a6f0df145ea1bb7ae51b821cf5e7927fdcfbdd0"
+dependencies = [
+ "pin-project-lite",
+ "tracing-attributes",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-attributes"
+version = "0.1.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "395ae124c09f9e6918a2310af6038fba074bcf474ac352496d5910dd59a2226d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "tracing-core"
+version = "0.1.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e672c95779cf947c5311f83787af4fa8fffd12fb27e4993211a84bdfd9610f9c"
+dependencies = [
+ "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8189decb5ac0fa7bc8b96b7cb9b2701d60d48805aca84a238004d665fcc4008"
+dependencies = [
+ "matchers",
+ "nu-ansi-term 0.46.0",
+ "once_cell",
+ "regex",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing",
+ "tracing-core",
+ "tracing-log",
+]
+
+[[package]]
+name = "tracing-tree"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f459ca79f1b0d5f71c54ddfde6debfc59c8b6eeb46808ae492077f739dc7b49c"
+dependencies = [
+ "nu-ansi-term 0.50.1",
+ "tracing-core",
+ "tracing-log",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "typenum"
 version = "1.17.0"
@@ -610,6 +790,12 @@ version = "1.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"
 
+[[package]]
+name = "valuable"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "830b7e5d4d90034032940e4ace0d9a9a057e7a45cd94e6c007832e39edb82f6d"
+
 [[package]]
 name = "version_check"
 version = "0.9.5"

src/bootstrap/Cargo.toml

@@ -7,6 +7,7 @@ default-run = "bootstrap"
 
 [features]
 build-metrics = ["sysinfo"]
+tracing = ["dep:tracing", "dep:tracing-subscriber", "dep:tracing-tree"]
 
 [lib]
 path = "src/lib.rs"
@@ -64,6 +65,11 @@ xz2 = "0.1"
 # Dependencies needed by the build-metrics feature
 sysinfo = { version = "0.33.0", default-features = false, optional = true, features = ["system"] }
 
+# Dependencies needed by the `logging` feature
+tracing = { version = "0.1", optional = true, features = ["attributes"] }
+tracing-subscriber = { version = "0.3", optional = true, features = ["env-filter", "fmt", "registry", "std"] }
+tracing-tree = { version = "0.4.0", optional = true }
+
 [target.'cfg(windows)'.dependencies.junction]
 version = "1.0.0"
 

src/bootstrap/bootstrap.py

@@ -1129,6 +1129,10 @@ def build_bootstrap_cmd(self, env):
             "-Zroot-dir=" + self.rust_root,
         ]
         args.extend("--verbose" for _ in range(self.verbose))
+
+        if "BOOTSTRAP_TRACING" in env:
+            args.append("--features=tracing")
+
         if self.use_locked_deps:
             args.append("--locked")
         if self.use_vendored_sources:

src/bootstrap/src/bin/main.rs

@@ -15,8 +15,18 @@ use bootstrap::{
     human_readable_changes, t,
 };
 use build_helper::ci::CiEnv;
-
+#[cfg(feature = "tracing")]
+use tracing::*;
+#[cfg(feature = "tracing")]
+use tracing_subscriber::EnvFilter;
+#[cfg(feature = "tracing")]
+use tracing_subscriber::prelude::*;
+
+#[cfg_attr(feature = "tracing", instrument(level = "trace", name = "main"))]
 fn main() {
+    #[cfg(feature = "tracing")]
+    setup_tracing();
+
     let args = env::args().skip(1).collect::<Vec<_>>();
 
     if Flags::try_parse_verbose_help(&args) {
@@ -187,3 +197,28 @@ fn check_version(config: &Config) -> Option<String> {
 
     Some(msg)
 }
+
+// # Note on `tracing` usage in bootstrap
+//
+// Due to the conditional compilation via the `tracing` cargo feature, this means that `tracing`
+// usages in bootstrap need to be also gated behind the `tracing` feature:
+//
+// - `tracing` macros (like `trace!`) and anything from `tracing`, `tracing_subscriber` and
+//   `tracing-tree` will need to be gated by `#[cfg(feature = "tracing")]`.
+// - `tracing`'s `#[instrument(..)]` macro will need to be gated like `#![cfg_attr(feature =
+//   "tracing", instrument(..))]`.
+#[cfg(feature = "tracing")]
+fn setup_tracing() {
+    let filter = EnvFilter::from_env("BOOTSTRAP_TRACING");
+    let layer = tracing_tree::HierarchicalLayer::default()
+        .with_writer(std::io::stderr)
+        .with_ansi(true)
+        .with_targets(true)
+        .with_bracketed_fields(true)
+        .with_indent_amount(2)
+        .with_indent_lines(true);
+    let subscriber = tracing_subscriber::registry().with(filter).with(layer);
+
+    tracing::subscriber::set_global_default(subscriber).unwrap();
+    trace!("tracing subscriber setup");
+}

src/doc/rustc-dev-guide/src/SUMMARY.md

@@ -75,6 +75,7 @@
 - [Prologue](./building/bootstrapping/intro.md)
 - [What Bootstrapping does](./building/bootstrapping/what-bootstrapping-does.md)
 - [How Bootstrap does it](./building/bootstrapping/how-bootstrap-does-it.md)
+- [Debugging bootstrap](./building/bootstrapping/debugging-bootstrap.md)
 
 # High-level Compiler Architecture