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unstable feature usage metrics
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yaahc committed Nov 13, 2024
1 parent 6503543 commit cd70825
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Showing 8 changed files with 146 additions and 2 deletions.
2 changes: 2 additions & 0 deletions Cargo.lock
Original file line number Diff line number Diff line change
Expand Up @@ -3684,6 +3684,8 @@ version = "0.0.0"
dependencies = [
"rustc_data_structures",
"rustc_span",
"serde",
"serde_json",
]

[[package]]
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17 changes: 17 additions & 0 deletions compiler/rustc_driver_impl/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,23 @@ fn run_compiler(
// Make sure name resolution and macro expansion is run.
queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering());

if let Some(metrics_dir) = &sess.opts.unstable_opts.metrics_dir {
queries.global_ctxt()?.enter(|tcxt| {
let output_filenames = tcxt.output_filenames(());
let mut metrics_file_name =
std::ffi::OsString::from("unstable_feature_usage_metrics-");
let mut metrics_path =
output_filenames.with_directory_and_extension(metrics_dir, "json");
let metrics_file_stem = metrics_path
.file_name()
.expect("there should be a valid default output filename");
metrics_file_name.push(metrics_file_stem);
metrics_path.pop();
metrics_path.push(metrics_file_name);
tcxt.features().dump_feature_usage_metrics(metrics_path)
});
}

if callbacks.after_expansion(compiler, queries) == Compilation::Stop {
return early_exit();
}
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2 changes: 2 additions & 0 deletions compiler/rustc_feature/Cargo.toml
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Expand Up @@ -7,4 +7,6 @@ edition = "2021"
# tidy-alphabetical-start
rustc_data_structures = { path = "../rustc_data_structures" }
rustc_span = { path = "../rustc_span" }
serde = { version = "1.0.125", features = [ "derive" ] }
serde_json = "1.0.59"
# tidy-alphabetical-end
46 changes: 46 additions & 0 deletions compiler/rustc_feature/src/unstable.rs
Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
//! List of the unstable feature gates.
use std::path::PathBuf;

use rustc_data_structures::fx::FxHashSet;
use rustc_span::Span;
use rustc_span::symbol::{Symbol, sym};
Expand Down Expand Up @@ -649,6 +651,50 @@ declare_features! (
// -------------------------------------------------------------------------
);

impl Features {
pub fn dump_feature_usage_metrics(&self, metrics_path: PathBuf) {
#[derive(serde::Serialize)]
struct LibFeature {
symbol: String,
}

#[derive(serde::Serialize)]
struct LangFeature {
symbol: String,
since: Option<String>,
}

#[derive(serde::Serialize)]
struct FeatureUsage {
lib_features: Vec<LibFeature>,
lang_features: Vec<LangFeature>,
}

println!("{}", metrics_path.display());
let metrics_file = std::fs::File::create(metrics_path).unwrap();
let metrics_file = std::io::BufWriter::new(metrics_file);

let lib_features = self
.enabled_lib_features
.iter()
.map(|EnabledLibFeature { gate_name, .. }| LibFeature { symbol: gate_name.to_string() })
.collect();

let lang_features = self
.enabled_lang_features
.iter()
.map(|EnabledLangFeature { gate_name, stable_since, .. }| LangFeature {
symbol: gate_name.to_string(),
since: stable_since.map(|since| since.to_string()),
})
.collect();

let feature_usage = FeatureUsage { lib_features, lang_features };

let _ = serde_json::to_writer(metrics_file, &feature_usage);
}
}

/// Some features are not allowed to be used together at the same time, if
/// the two are present, produce an error.
///
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2 changes: 1 addition & 1 deletion compiler/rustc_session/src/config.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1068,7 +1068,7 @@ impl OutputFilenames {
self.with_directory_and_extension(&self.out_directory, extension)
}

fn with_directory_and_extension(&self, directory: &PathBuf, extension: &str) -> PathBuf {
pub fn with_directory_and_extension(&self, directory: &PathBuf, extension: &str) -> PathBuf {
let mut path = directory.join(&self.filestem);
path.set_extension(extension);
path
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2 changes: 1 addition & 1 deletion compiler/rustc_session/src/options.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1889,7 +1889,7 @@ options! {
meta_stats: bool = (false, parse_bool, [UNTRACKED],
"gather metadata statistics (default: no)"),
metrics_dir: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
"stores metrics about the errors being emitted by rustc to disk"),
"the directory metrics emitted by rustc are dumped into (implicitly enables default set of metrics)"),
mir_emit_retag: bool = (false, parse_bool, [TRACKED],
"emit Retagging MIR statements, interpreted e.g., by miri; implies -Zmir-opt-level=0 \
(default: no)"),
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9 changes: 9 additions & 0 deletions tests/run-make/unstable-feature-usage-metrics/lib.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
#![feature(ascii_char)] // random lib feature
#![feature(box_patterns)] // random lang feature

// picked arbitrary unstable features, just need a random lib and lang feature, ideally ones that
// won't be stabilized any time soon so we don't have to update this test

fn main() {
println!("foobar");
}
68 changes: 68 additions & 0 deletions tests/run-make/unstable-feature-usage-metrics/rmake.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,68 @@
//! This test checks if unstable feature usage metric dump files `unstable-feature-usage*.json` work
//! as expected.
//!
//! - Basic sanity checks on a default ICE dump.
//!
//! See <https://github.com/rust-lang/rust/issues/129485>.
//!
//! # Test history
//!
//! - forked from dump-ice-to-disk test, which has flakeyness issues on i686-mingw, I'm assuming
//! those will be present in this test as well on the same platform
//@ ignore-windows
//FIXME(#128911): still flakey on i686-mingw.

use std::path::{Path, PathBuf};

use run_make_support::{
cwd, has_extension, filename_contains, rfs, run_in_tmpdir, rustc, serde_json, shallow_find_files,
};

fn find_feature_usage_metrics<P: AsRef<Path>>(dir: P) -> Vec<PathBuf> {
shallow_find_files(dir, |path| {
if filename_contains(path, "unstable_feature_usage") && has_extension(path, "json") {
true
} else {
dbg!(path);
false
}
})
}

fn main() {
test_metrics_dump();
}

#[track_caller]
fn test_metrics_dump() {
run_in_tmpdir(|| {
let metrics_dir = cwd().join("metrics");
rustc()
.input("lib.rs")
.env("RUST_BACKTRACE", "short")
.arg(format!("-Zmetrics-dir={}", metrics_dir.display()))
.run();
let mut metrics = find_feature_usage_metrics(&metrics_dir);
let json_path =
metrics.pop().expect("there should be one metrics file in the output directory");

assert_eq!(
0,
metrics.len(),
"there should be no more than one metrics file in the output directory"
);

let message = rfs::read_to_string(json_path);
let parsed: serde_json::Value =
serde_json::from_str(&message).expect("metrics should be dumped as json");
let expected = serde_json::json!(
{
"lib_features":[{"symbol":"ascii_char"}],
"lang_features":[{"symbol":"box_patterns","since":null}]
}
);

assert_eq!(expected, parsed);
});
}

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