feat(trim-paths): rustdoc supports trim-paths for diagnostics

This enables rustdoc invocation from `cargo doc` to trim paths
in diagnostics. Doc tests are out-of-scope, as they are handled
in a different mechanism, which needs more cares.

Author: weihanglo

src/cargo/core/compiler/mod.rs

@@ -97,6 +97,7 @@ use crate::util::{add_path_args, internal};
 use cargo_util::{paths, ProcessBuilder, ProcessError};
 use cargo_util_schemas::manifest::TomlDebugInfo;
 use cargo_util_schemas::manifest::TomlTrimPaths;
+use cargo_util_schemas::manifest::TomlTrimPathsValue;
 use rustfix::diagnostics::Applicability;
 
 const RUSTDOC_CRATE_VERSION_FLAG: &str = "--crate-version";
@@ -737,6 +738,10 @@ fn prepare_rustdoc(build_runner: &BuildRunner<'_, '_>, unit: &Unit) -> CargoResu
     add_error_format_and_color(build_runner, &mut rustdoc);
     add_allow_features(build_runner, &mut rustdoc);
 
+    if let Some(trim_paths) = unit.profile.trim_paths.as_ref() {
+        trim_paths_args_rustdoc(&mut rustdoc, build_runner, unit, trim_paths)?;
+    }
+
     rustdoc.args(unit.pkg.manifest().lint_rustflags());
     if let Some(args) = build_runner.bcx.extra_args_for(unit) {
         rustdoc.args(args);
@@ -1223,6 +1228,32 @@ fn features_args(unit: &Unit) -> Vec<OsString> {
     args
 }
 
+/// Like [`trim_paths_args`] but for rustdoc invocations.
+fn trim_paths_args_rustdoc(
+    cmd: &mut ProcessBuilder,
+    build_runner: &BuildRunner<'_, '_>,
+    unit: &Unit,
+    trim_paths: &TomlTrimPaths,
+) -> CargoResult<()> {
+    match trim_paths {
+        // rustdoc supports diagnostics trimming only.
+        TomlTrimPaths::Values(values) if !values.contains(&TomlTrimPathsValue::Diagnostics) => {
+            return Ok(())
+        }
+        _ => {}
+    }
+
+    // feature gate was checked during manifest/config parsing.
+    cmd.arg("-Zunstable-options");
+
+    // Order of `--remap-path-prefix` flags is important for `-Zbuild-std`.
+    // We want to show `/rustc/<hash>/library/std` instead of `std-0.0.0`.
+    cmd.arg(package_remap(build_runner, unit));
+    cmd.arg(sysroot_remap(build_runner, unit));
+
+    Ok(())
+}
+
 /// Generates the `--remap-path-scope` and `--remap-path-prefix` for [RFC 3127].
 /// See also unstable feature [`-Ztrim-paths`].
 ///

tests/testsuite/profile_trim_paths.rs

@@ -831,8 +831,10 @@ fn rustdoc_diagnostics_works() {
         .masquerade_as_nightly_cargo(&["-Ztrim-paths"])
         .with_stderr_data(str![[r#"
 ...
+[RUNNING] `[..]rustc [..]-Zremap-path-scope=diagnostics --remap-path-prefix=[ROOT]/home/.cargo/registry/src= --remap-path-prefix=[..]/lib/rustlib/src/rust=/rustc/[..]`
+...
 [WARNING] unopened HTML tag `script`
- --> [ROOT]/home/.cargo/registry/src/-[HASH]/bar-0.0.1/src/lib.rs:2:17
+ --> -[..]/bar-0.0.1/src/lib.rs:2:17
 ...
 "#]])
         .run();