docs(log): brief description for each log message field

Author: weihanglo

src/cargo/util/log_message.rs

@@ -18,61 +18,97 @@ use crate::core::compiler::fingerprint::DirtyReason;
 pub enum LogMessage {
     /// Emitted when a build starts.
     BuildStarted {
+        /// Current working directory.
         cwd: PathBuf,
+        /// Host triple.
         host: String,
+        /// Number of parallel jobs.
         jobs: u32,
+        /// Build profile name (e.g., "dev", "release").
         profile: String,
+        /// The rustc version (`1.23.4-beta.2`).
         rustc_version: String,
+        /// The rustc verbose version information (the output of `rustc -vV`).
         rustc_version_verbose: String,
+        /// Target directory for build artifacts.
         target_dir: PathBuf,
+        /// Workspace root directory.
         workspace_root: PathBuf,
     },
     /// Emitted when a compilation unit starts.
     UnitStarted {
+        /// Package ID specification.
         package_id: PackageIdSpec,
+        /// Cargo target (lib, bin, example, etc.).
         target: Target,
+        /// The compilation action this unit is for (check, build, test, etc.).
         mode: CompileMode,
+        /// Unit index for compact reference in subsequent events.
         index: u64,
+        /// Seconds elapsed from build start.
         elapsed: f64,
     },
     /// Emitted when a section (e.g., rmeta, link) of the compilation unit finishes.
     UnitRmetaFinished {
+        /// Unit index from the associated unit-started event.
         index: u64,
+        /// Seconds elapsed from build start.
         elapsed: f64,
+        /// Unit indices that were unblocked by this rmeta completion.
         #[serde(skip_serializing_if = "Vec::is_empty")]
         unblocked: Vec<u64>,
     },
     /// Emitted when a section (e.g., rmeta, link) of the compilation unit starts.
+    ///
+    /// Requires `-Zsection-timings` to be enabled.
     UnitSectionStarted {
+        /// Unit index from the associated unit-started event.
         index: u64,
+        /// Seconds elapsed from build start.
         elapsed: f64,
+        /// Section name from rustc's `-Zjson=timings` (e.g., "codegen", "link").
         section: String,
     },
     /// Emitted when a section (e.g., rmeta, link) of the compilation unit finishes.
+    ///
+    /// Requires `-Zsection-timings` to be enabled.
     UnitSectionFinished {
+        /// Unit index from the associated unit-started event.
         index: u64,
+        /// Seconds elapsed from build start.
         elapsed: f64,
+        /// Section name from rustc's `-Zjson=timings` (e.g., "codegen", "link").
         section: String,
     },
     /// Emitted when a compilation unit finishes.
     UnitFinished {
+        /// Unit index from the associated unit-started event.
         index: u64,
+        /// Seconds elapsed from build start.
         elapsed: f64,
+        /// Unit indices that were unblocked by this completion.
         #[serde(skip_serializing_if = "Vec::is_empty")]
         unblocked: Vec<u64>,
     },
     /// Emitted when a unit needs to be rebuilt.
     Rebuild {
+        /// Package ID specification.
         package_id: PackageIdSpec,
+        /// Cargo target (lib, bin, example, etc.).
         target: Target,
+        /// The compilation action this unit is for (check, build, test, etc.).
         mode: CompileMode,
+        /// Reason why the unit is dirty and needs rebuilding.
         cause: DirtyReason,
     },
 }
 
+/// Cargo target information.
 #[derive(Serialize)]
 pub struct Target {
+    /// Target name.
     name: String,
+    /// Target kind (lib, bin, test, bench, example, build-script).
     kind: &'static str,
 }