Default macOS targets to unpacked debuginfo

This commit continues the work from rust-lang#9112 to enable `unpacked` split
debuginfo on macOS targets by default. This has been discussed on [internals]
for awhile now and no breakage has emerged while significant speedups
have. This is expected to be a compile-time and `target`-directory size
win for almost all macOS Rust projects.

While breakage is possible it's possible to mitigate this with
project-local or global cargo configuration of the `dev` and `test` profiles.

[internals]: https://internals.rust-lang.org/t/help-test-faster-incremental-debug-macos-builds-on-nightly/14016/9

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

@@ -1614,14 +1614,6 @@ fn _process(t: &OsStr) -> ProcessBuilder {
         p.env("PATH", new_path);
     }
 
-    if cfg!(target_os = "macos") {
-        // This makes the test suite run substantially faster.
-        p.env("CARGO_PROFILE_DEV_SPLIT_DEBUGINFO", "unpacked")
-            .env("CARGO_PROFILE_TEST_SPLIT_DEBUGINFO", "unpacked")
-            .env("CARGO_PROFILE_RELEASE_SPLIT_DEBUGINFO", "unpacked")
-            .env("CARGO_PROFILE_BENCH_SPLIT_DEBUGINFO", "unpacked");
-    }
-
     p.cwd(&paths::root())
         .env("HOME", paths::home())
         .env("CARGO_HOME", paths::home().join(".cargo"))

src/cargo/core/compiler/standard_lib.rs

@@ -158,17 +158,18 @@ pub fn generate_std_roots(
         // in time is minimal, and the difference in caching is
         // significant.
         let mode = CompileMode::Build;
-        let profile = profiles.get_profile(
-            pkg.package_id(),
-            /*is_member*/ false,
-            /*is_local*/ false,
-            unit_for,
-            mode,
-        );
         let features = std_features.activated_features(pkg.package_id(), FeaturesFor::NormalOrDev);
 
         for kind in kinds {
             let list = ret.entry(*kind).or_insert_with(Vec::new);
+            let profile = profiles.get_profile(
+                pkg.package_id(),
+                /*is_member*/ false,
+                /*is_local*/ false,
+                unit_for,
+                mode,
+                *kind,
+            );
             list.push(interner.intern(
                 pkg,
                 lib,

src/cargo/core/compiler/unit_dependencies.rs

@@ -585,6 +585,7 @@ fn new_unit_dep(
         is_local,
         unit_for,
         mode,
+        kind,
     );
     new_unit_dep_with_profile(state, parent, pkg, target, unit_for, kind, mode, profile)
 }

src/cargo/core/profiles.rs

@@ -1,4 +1,4 @@
-use crate::core::compiler::{CompileMode, Unit};
+use crate::core::compiler::{CompileKind, CompileMode, Unit};
 use crate::core::resolver::features::FeaturesFor;
 use crate::core::{Feature, PackageId, PackageIdSpec, Resolve, Shell, Target, Workspace};
 use crate::util::errors::CargoResultExt;
@@ -291,6 +291,7 @@ impl Profiles {
         is_local: bool,
         unit_for: UnitFor,
         mode: CompileMode,
+        kind: CompileKind,
     ) -> Profile {
         let (profile_name, inherits) = if !self.named_profiles_enabled {
             // With the feature disabled, we degrade `--profile` back to the
@@ -346,6 +347,23 @@ impl Profiles {
             }
         }
 
+        // Default macOS debug information to being stored in the "unpacked"
+        // split-debuginfo format. At the time of this writing that's the only
+        // platform which has a stable `-Csplit-debuginfo` option for rustc,
+        // and it's typically much faster than running `dsymutil` on all builds
+        // in incremental cases.
+        if let Some(debug) = profile.debuginfo {
+            if profile.split_debuginfo.is_none() && debug > 0 {
+                let target = match &kind {
+                    CompileKind::Host => self.rustc_host.as_str(),
+                    CompileKind::Target(target) => target.short_name(),
+                };
+                if target.contains("-apple-") {
+                    profile.split_debuginfo = Some(InternedString::new("unpacked"));
+                }
+            }
+        }
+
         // Incremental can be globally overridden.
         if let Some(v) = self.incremental {
             profile.incremental = v;

src/cargo/ops/cargo_compile.rs

@@ -909,19 +909,20 @@ fn generate_targets(
             };
 
             let is_local = pkg.package_id().source_id().is_path();
-            let profile = profiles.get_profile(
-                pkg.package_id(),
-                ws.is_member(pkg),
-                is_local,
-                unit_for,
-                target_mode,
-            );
 
             // No need to worry about build-dependencies, roots are never build dependencies.
             let features_for = FeaturesFor::from_for_host(target.proc_macro());
             let features = resolved_features.activated_features(pkg.package_id(), features_for);
 
             for kind in requested_kinds {
+                let profile = profiles.get_profile(
+                    pkg.package_id(),
+                    ws.is_member(pkg),
+                    is_local,
+                    unit_for,
+                    target_mode,
+                    *kind,
+                );
                 let unit = interner.intern(
                     pkg,
                     target,

src/doc/src/reference/profiles.md

@@ -83,10 +83,12 @@ controls whether debug information, if generated, is either placed in the
 executable itself or adjacent to it.
 
 This option is a string and acceptable values are the same as those the
-[compiler accepts][`-C split-debuginfo` flag]. See that documentation for the
-default behavior, which is platform-specific. Some options are only available
-on the [nightly channel]. The default may change in the future once more
-testing has been performed, and support for DWARF is stabilized.
+[compiler accepts][`-C split-debuginfo` flag]. The default value for this option
+is `unpacked` on macOS for profiles that have debug information otherwise
+enabled. Otherwise the default for this option is [documented with rustc][`-C
+split-debuginfo` flag] and is platform-specific. Some options are only
+available on the [nightly channel]. The Cargo default may change in the future
+once more testing has been performed, and support for DWARF is stabilized.
 
 [nightly channel]: ../../book/appendix-07-nightly-rust.html
 [`-C split-debuginfo` flag]: ../../rustc/codegen-options/index.html#split-debuginfo

tests/testsuite/profile_config.rs

@@ -342,7 +342,7 @@ fn named_config_profile() {
     // foo -> middle -> bar -> dev
     // middle exists in Cargo.toml, the others in .cargo/config
     use super::config::ConfigBuilder;
-    use cargo::core::compiler::CompileMode;
+    use cargo::core::compiler::{CompileKind, CompileMode};
     use cargo::core::profiles::{Profiles, UnitFor};
     use cargo::core::{PackageId, Workspace};
     use cargo::util::interning::InternedString;
@@ -403,7 +403,8 @@ fn named_config_profile() {
 
     // normal package
     let mode = CompileMode::Build;
-    let p = profiles.get_profile(a_pkg, true, true, UnitFor::new_normal(), mode);
+    let kind = CompileKind::Host;
+    let p = profiles.get_profile(a_pkg, true, true, UnitFor::new_normal(), mode, kind);
     assert_eq!(p.name, "foo");
     assert_eq!(p.codegen_units, Some(2)); // "foo" from config
     assert_eq!(p.opt_level, "1"); // "middle" from manifest
@@ -412,7 +413,7 @@ fn named_config_profile() {
     assert_eq!(p.overflow_checks, true); // "dev" built-in (ignore package override)
 
     // build-override
-    let bo = profiles.get_profile(a_pkg, true, true, UnitFor::new_host(false), mode);
+    let bo = profiles.get_profile(a_pkg, true, true, UnitFor::new_host(false), mode, kind);
     assert_eq!(bo.name, "foo");
     assert_eq!(bo.codegen_units, Some(6)); // "foo" build override from config
     assert_eq!(bo.opt_level, "0"); // default to zero
@@ -421,7 +422,7 @@ fn named_config_profile() {
     assert_eq!(bo.overflow_checks, true); // SAME as normal
 
     // package overrides
-    let po = profiles.get_profile(dep_pkg, false, true, UnitFor::new_normal(), mode);
+    let po = profiles.get_profile(dep_pkg, false, true, UnitFor::new_normal(), mode, kind);
     assert_eq!(po.name, "foo");
     assert_eq!(po.codegen_units, Some(7)); // "foo" package override from config
     assert_eq!(po.opt_level, "1"); // SAME as normal