feat(compile-time-deps): Add cli flag --compile-time-deps and adjust docs

src/bin/cargo/commands/build.rs

@@ -38,6 +38,7 @@ pub fn cli() -> Command {
         .arg_build_plan()
         .arg_unit_graph()
         .arg_timings()
+        .arg_compile_time_deps()
         .arg_manifest_path()
         .arg_lockfile_path()
         .arg_ignore_rust_version()

src/bin/cargo/commands/check.rs

@@ -35,6 +35,7 @@ pub fn cli() -> Command {
         .arg_target_dir()
         .arg_unit_graph()
         .arg_timings()
+        .arg_compile_time_deps()
         .arg_manifest_path()
         .arg_lockfile_path()
         .arg_ignore_rust_version()

src/cargo/util/command_prelude.rs

@@ -521,6 +521,10 @@ pub trait CommandExt: Sized {
             .hide(true),
         )
     }
+
+    fn arg_compile_time_deps(self) -> Self {
+        self._arg(flag("compile-time-deps", "").hide(true))
+    }
 }
 
 impl CommandExt for Command {
@@ -806,6 +810,7 @@ Run `{cmd}` to see possible targets."
         build_config.build_plan = self.flag("build-plan");
         build_config.unit_graph = self.flag("unit-graph");
         build_config.future_incompat_report = self.flag("future-incompat-report");
+        build_config.compile_time_deps_only = self.flag("compile-time-deps");
 
         if self._contains("timings") {
             for timing_output in self._values_of("timings") {
@@ -840,6 +845,10 @@ Run `{cmd}` to see possible targets."
             gctx.cli_unstable()
                 .fail_if_stable_opt("--unit-graph", 8002)?;
         }
+        if build_config.compile_time_deps_only {
+            gctx.cli_unstable()
+                .fail_if_stable_opt("--compile-time-deps", 14434)?;
+        }
 
         let opts = CompileOptions {
             build_config,

src/doc/src/reference/unstable.md

@@ -2190,3 +2190,17 @@ More information can be found in the [config chapter](config.md#cache).
 ## doctest-xcompile
 
 Doctest cross-compiling is now unconditionally enabled starting in Rust 1.89. Running doctests with `cargo test` will now honor the `--target` flag.
+
+## compile-time-deps
+
+This permanently-unstable flag to only build proc-macros and build scripts (and their required dependencies),
+as well as run the build scripts.
+
+It is intended for use by tools like rust-analyzer and will never be stabilized.
+
+Example:
+
+```console
+cargo +nightly build --compile-time-deps -Z unstable-options
+cargo +nightly check --compile-time-deps --all-targets -Z unstable-options
+```

tests/testsuite/compile_time_deps.rs

@@ -8,13 +8,11 @@ fn gated_by_unstable_opts() {
         .build();
 
     p.cargo("check --compile-time-deps")
-        .with_status(1)
+        .with_status(101)
         .with_stderr_data(str![[r#"
-[ERROR] unexpected argument '--compile-time-deps' found
+[ERROR] the `--compile-time-deps` flag is unstable, and only available on the nightly channel of Cargo, but this is the `stable` channel
-
+See https://doc.rust-lang.org/book/appendix-07-nightly-rust.html for more information about Rust release channels.
-Usage: cargo check [OPTIONS]
+See https://github.com/rust-lang/cargo/issues/14434 for more information about the `--compile-time-deps` flag.
-
-For more information, try '--help'.
 
 "#]])
         .run();
@@ -55,11 +53,10 @@ fn non_comp_time_dep() {
         .file("bar/src/lib.rs", r#"pub fn bar() {}"#)
         .build();
 
-    p.cargo("check")
+    p.cargo("-Zunstable-options check --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
 [LOCKING] 1 package to latest compatible version
-[CHECKING] bar v0.0.1 ([ROOT]/foo/bar)
-[CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -151,11 +148,11 @@ fn proc_macro_dep() {
         .file("baz/src/lib.rs", r#"pub fn baz() {}"#)
         .build();
 
-    p.cargo("check --package foo")
+    p.cargo("-Zunstable-options check --package foo --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
 [COMPILING] baz v0.0.1 ([ROOT]/foo/baz)
 [COMPILING] bar v0.0.1 ([ROOT]/foo/bar)
-[CHECKING] foo v0.0.1 ([ROOT]/foo/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -163,10 +160,9 @@ fn proc_macro_dep() {
 
     p.cargo("clean").run();
 
-    p.cargo("check --package bar")
+    p.cargo("-Zunstable-options check --package bar --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
-[CHECKING] baz v0.0.1 ([ROOT]/foo/baz)
-[CHECKING] bar v0.0.1 ([ROOT]/foo/bar)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -174,10 +170,11 @@ fn proc_macro_dep() {
 
     p.cargo("clean").run();
 
-    p.cargo("check --package bar --all-targets")
+    p.cargo("-Zunstable-options check --package bar --all-targets --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
-[CHECKING] baz v0.0.1 ([ROOT]/foo/baz)
+[COMPILING] baz v0.0.1 ([ROOT]/foo/baz)
-[CHECKING] bar v0.0.1 ([ROOT]/foo/bar)
+[COMPILING] bar v0.0.1 ([ROOT]/foo/bar)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -241,7 +238,8 @@ fn build_dep() {
         .file("bar/baz/src/lib.rs", r#"pub fn baz() {}"#)
         .build();
 
-    p.cargo("check")
+    p.cargo("-Zunstable-options check --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
 [LOCKING] 2 packages to latest compatible versions
 [COMPILING] baz v0.0.1 ([ROOT]/foo/bar/baz)
@@ -314,12 +312,12 @@ fn indirect_comp_time_dep() {
         .file("bar/baz/src/lib.rs", r#"pub fn baz() {}"#)
         .build();
 
-    p.cargo("check")
+    p.cargo("-Zunstable-options check --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
 [LOCKING] 2 packages to latest compatible versions
 [COMPILING] baz v0.0.1 ([ROOT]/foo/bar/baz)
 [COMPILING] bar v0.0.1 ([ROOT]/foo/bar)
-[CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -379,21 +377,21 @@ fn tests_target() {
         )
         .build();
 
-    p.cargo("check --tests")
+    p.cargo("-Zunstable-options check --tests --compile-time-deps")
         .with_stderr_data(str![[r#"
 [LOCKING] 1 package to latest compatible version
 [COMPILING] bar v0.0.1 ([ROOT]/foo/bar)
-[CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .run();
 
     p.cargo("clean").run();
 
-    p.cargo("check")
+    p.cargo("-Zunstable-options check --compile-time-deps")
+        .masquerade_as_nightly_cargo(&["compile-time-deps"])
         .with_stderr_data(str![[r#"
-[CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])