feat(report): cargo report timings HTML replay (#16377)

### What does this PR try to resolve?

This implements `cargo report timings` HTML replay feature.

The help text looks like:

```
Reports the build timings of previous builds (unstable)

Usage: cargo report timings [OPTIONS]

Options:
      --open              Opens the timing report in a browser
      ...
```

Part of <#15844>

### How to test and review this PR?

Open questions:

* [ ] The replayed HTML report will be written to
  * If in a Cargo workspace, write to `<artifact-dir>/cargo-timings/`
  * Otherwise, write to a temp directory
* [ ] The log discovery logic
  * Currently look at the newest log file for the workspace.
* If not in a workspace, pick the newest log file in the log directory.
* [ ] Snapshots HTML report and log files are added.
  * They are huge in size. Should we not do this?
  * Benefit: HTML snapshots help us know better when it is broken

### Things left (but should do it follow-up PRs)

* [ ] `cargo help` hasn't yet worked with with nested commands.
* [ ] There are some more information required by HTML report, but these
don't affect the major use of the report IMO.
	* [ ] fresh/dirty/total units
	* [ ] information of root units
	* [ ] enabled features for each unit
	* [ ] `--target` platform
	* [ ] CPU usage metrics
* [x] number of available parallelism
#16378

Author: epage

.ignore

@@ -12,4 +12,8 @@ src/etc/man
 !src/doc/src/commands/index.md
 !src/doc/src/commands/manifest-commands.md
 !src/doc/src/commands/package-commands.md
-!src/doc/src/commands/publishg-commands.md
+!src/doc/src/commands/publishing-commands.md
+
+# Snapshots of HTML reports and log files are just too large
+tests/testsuite/**/*.jsonl
+tests/testsuite/**/*.html

crates/cargo-test-support/src/paths.rs

@@ -119,6 +119,41 @@ pub fn cargo_home() -> PathBuf {
     home().join(".cargo")
 }
 
+/// Path to the current test's `$CARGO_LOG`
+///
+/// ex: `$CARGO_TARGET_TMPDIR/cit/t0/home/.cargo/log`
+pub fn log_dir() -> PathBuf {
+    cargo_home().join("log")
+}
+
+/// Path to the current test's `$CARGO_LOG` file
+///
+/// ex: `$CARGO_TARGET_TMPDIR/cit/t0/home/.cargo/log/<id>.jsonl`
+///
+/// This also asserts the number of log files is exactly the same as `idx + 1`.
+pub fn log_file(idx: usize) -> PathBuf {
+    let log_dir = log_dir();
+
+    let entries = std::fs::read_dir(&log_dir).unwrap();
+    let mut log_files: Vec<_> = entries
+        .filter_map(Result::ok)
+        .filter(|e| e.path().extension().and_then(|s| s.to_str()) == Some("jsonl"))
+        .collect();
+
+    // Sort them to get chronological order
+    log_files.sort_unstable_by(|a, b| a.file_name().to_str().cmp(&b.file_name().to_str()));
+
+    assert_eq!(
+        idx + 1,
+        log_files.len(),
+        "unexpected number of log files: {}, expected {}",
+        log_files.len(),
+        idx + 1
+    );
+
+    log_files[idx].path()
+}
+
 /// Common path and file operations
 pub trait CargoPathExt {
     fn to_url(&self) -> url::Url;

src/bin/cargo/commands/report.rs

@@ -1,6 +1,10 @@
 use crate::command_prelude::*;
-use cargo::core::compiler::future_incompat::{OnDiskReports, REPORT_PREAMBLE};
+
+use cargo::CargoResult;
+use cargo::core::compiler::future_incompat::OnDiskReports;
+use cargo::core::compiler::future_incompat::REPORT_PREAMBLE;
 use cargo::drop_println;
+use cargo::ops;
 
 pub fn cli() -> Command {
     subcommand("report")
@@ -23,11 +27,28 @@ pub fn cli() -> Command {
                 )
                 .arg_package("Package to display a report for"),
         )
+        .subcommand(
+            subcommand("timings")
+                .about("Reports the build timings of previous builds (unstable)")
+                .arg(flag("open", "Opens the timing report in a browser")),
+        )
 }
 
 pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
     match args.subcommand() {
         Some(("future-incompatibilities", args)) => report_future_incompatibilities(gctx, args),
+        Some(("timings", args)) => {
+            gctx.cli_unstable().fail_if_stable_command(
+                gctx,
+                "report timings",
+                15844,
+                "build-analysis",
+                gctx.cli_unstable().build_analysis,
+            )?;
+            let opts = timings_opts(gctx, args)?;
+            ops::report_timings(gctx, opts)?;
+            Ok(())
+        }
         Some((cmd, _)) => {
             unreachable!("unexpected command {}", cmd)
         }
@@ -49,3 +70,12 @@ fn report_future_incompatibilities(gctx: &GlobalContext, args: &ArgMatches) -> C
     drop(gctx.shell().print_ansi_stdout(report.as_bytes()));
     Ok(())
 }
+
+fn timings_opts<'a>(
+    gctx: &'a GlobalContext,
+    args: &ArgMatches,
+) -> CargoResult<ops::ReportTimingsOptions<'a>> {
+    let open_result = args.get_flag("open");
+
+    Ok(ops::ReportTimingsOptions { open_result, gctx })
+}

src/cargo/ops/cargo_doc.rs

@@ -1,17 +1,15 @@
+use crate::core::Workspace;
 use crate::core::compiler::{Compilation, CompileKind};
-use crate::core::{Shell, Workspace, shell::Verbosity};
+use crate::core::shell::Verbosity;
 use crate::ops;
 use crate::util;
 use crate::util::CargoResult;
-use crate::util::context::{GlobalContext, PathAndArgs};
 
 use anyhow::{Error, bail};
 use cargo_util::ProcessBuilder;
 
 use std::ffi::OsString;
-use std::path::Path;
 use std::path::PathBuf;
-use std::process::Command;
 use std::str::FromStr;
 
 /// Format of rustdoc [`--output-format`][1].
@@ -75,14 +73,7 @@ pub fn doc(ws: &Workspace<'_>, options: &DocOptions) -> CargoResult<()> {
         let path = path_by_output_format(&compilation, &kind, &name, &options.output_format);
 
         if path.exists() {
-            let config_browser = {
-                let cfg: Option<PathAndArgs> = ws.gctx().get("doc.browser")?;
-                cfg.map(|path_args| (path_args.path.resolve_program(ws.gctx()), path_args.args))
-            };
-            let mut shell = ws.gctx().shell();
-            let link = shell.err_file_hyperlink(&path);
-            shell.status("Opening", format!("{link}{}{link:#}", path.display()))?;
-            open_docs(&path, &mut shell, config_browser, ws.gctx())?;
+            util::open::open(&path, ws.gctx())?;
         }
     } else if ws.gctx().shell().verbosity() == Verbosity::Verbose {
         for name in &compilation.root_crate_names {
@@ -216,33 +207,3 @@ fn path_by_output_format(
             .join("index.html")
     }
 }
-
-fn open_docs(
-    path: &Path,
-    shell: &mut Shell,
-    config_browser: Option<(PathBuf, Vec<String>)>,
-    gctx: &GlobalContext,
-) -> CargoResult<()> {
-    let browser =
-        config_browser.or_else(|| Some((PathBuf::from(gctx.get_env_os("BROWSER")?), Vec::new())));
-
-    match browser {
-        Some((browser, initial_args)) => {
-            if let Err(e) = Command::new(&browser).args(initial_args).arg(path).status() {
-                shell.warn(format!(
-                    "Couldn't open docs with {}: {}",
-                    browser.to_string_lossy(),
-                    e
-                ))?;
-            }
-        }
-        None => {
-            if let Err(e) = opener::open(&path) {
-                let e = e.into();
-                crate::display_warning_with_error("couldn't open docs", &e, shell);
-            }
-        }
-    };
-
-    Ok(())
-}

src/cargo/ops/cargo_report/mod.rs

@@ -0,0 +1 @@
+pub mod timings;