Add unstable -Zsection-timings flag

Author: Kobzol

src/cargo/core/features.rs

@@ -856,6 +856,7 @@ unstable_cli_options!(
     rustdoc_scrape_examples: bool = ("Allows Rustdoc to scrape code examples from reverse-dependencies"),
     sbom: bool = ("Enable the `sbom` option in build config in .cargo/config.toml file"),
     script: bool = ("Enable support for single-file, `.rs` packages"),
+    section_timings: bool = ("Enable support for extended compilation sections in --timings output"),
     separate_nightlies: bool,
     skip_rustdoc_fingerprint: bool,
     target_applies_to_host: bool = ("Enable the `target-applies-to-host` key in the .cargo/config.toml file"),
@@ -1380,6 +1381,7 @@ impl CliUnstable {
             "rustdoc-map" => self.rustdoc_map = parse_empty(k, v)?,
             "rustdoc-scrape-examples" => self.rustdoc_scrape_examples = parse_empty(k, v)?,
             "sbom" => self.sbom = parse_empty(k, v)?,
+            "section-timings" => self.section_timings = parse_empty(k, v)?,
             "separate-nightlies" => self.separate_nightlies = parse_empty(k, v)?,
             "checksum-freshness" => self.checksum_freshness = parse_empty(k, v)?,
             "skip-rustdoc-fingerprint" => self.skip_rustdoc_fingerprint = parse_empty(k, v)?,

src/doc/src/reference/unstable.md

@@ -1938,6 +1938,18 @@ For example:
 cargo +nightly fix -Zfix-edition=end=2024,future
 ```
 
+## section-timings
+* Original Pull Request: [#15780](https://github.com/rust-lang/cargo/pull/15780)
+* Tracking Issue: [#15817](https://github.com/rust-lang/cargo/issues/15817)
+
+This feature can be used to extend the output of `cargo build --timings`. It will tell rustc
+to produce timings of individual compilation sections, which will be then displayed in the timings
+HTML/JSON output.
+
+```console
+cargo +nightly -Zsection-timings build --timings
+```
+
 # Stabilized and removed features
 
 ## Compile progress