Rework cargo-test-support & testsuite to use CARGO_BIN_EXE_* for Cargo (#15692)

### What does this PR try to resolve?

This PR reworks `cargo-test-support` and `testsuite` to use Snapbox's
[`cargo_bin!()`](https://docs.rs/snapbox/latest/snapbox/cmd/macro.cargo_bin.html)
instead of
[`cargo_bin()`](https://docs.rs/snapbox/latest/snapbox/cmd/fn.cargo_bin.html)
which makes assumptions about the structure of Cargo's build directory.
`cargo_bin!()` uses `CARGO_BIN_EXE_*` for locating the `cargo` binary
which should be more resilient to directory/layout changes.

Linking a relevant Zulip discussion
[here](https://rust-lang.zulipchat.com/#narrow/channel/246057-t-cargo/topic/cargo_bin_exe.20and.20tests/with/513638220)[#t-cargo
> cargo_bin_exe and
tests](https://rust-lang.zulipchat.com/#narrow/channel/246057-t-cargo/topic/cargo_bin_exe.20and.20tests/with/513638220)

As shown in that link, we could make these variables available at
runtime and not need to do this. However, `cargo-test-support`, as an
API, is a bit weird in that it is baking in support for one specific
binary. This can be confusing for callers and makes it more annoying for
callers provide their own `fn cargo`, e.g. see crate-ci/cargo-fixit#7

### Implementation Notes

`cargo_bin!()` only works when being called from the `testsuite` as it's
only set when executing integration tests and `cargo-test-support` is a
regular crate.
To make this change, I introduced an extension trait `CargoProjectExt`
in `testsuite` for running `.cargo()` and implemented it on `Project`.

In `cargo-test-support` other functionality relies on `.cargo()` so
these also needed to be moved to `testsuite`
*
[`src/tools.rs`](https://github.com/rust-lang/cargo/blob/master/crates/cargo-test-support/src/tools.rs)
* Parts
[`src/cross_compile`](https://github.com/rust-lang/cargo/blob/master/crates/cargo-test-support/src/cross_compile.rs)
* I had to split this up unfortunately, as `disabled()` requires running
Cargo to check if we should disable cross compile tests.
* Other fns in `cross_compile` are used in `cargo-test-support` so
moving everything to `testsuite` would have ended up requiring moving
many things to test suite.

### How to test and review this PR?

I'd definitely recommend reviewing commit by commit.
There are a lot of diffs due to the nature of reorganizing things.
I did my best to split things things into smaller PRs but they still
contain a lot of `use` statement diffs.

r? @epage

Author: epage

Cargo.lock

@@ -32,7 +32,7 @@ cargo-credential-macos-keychain = { version = "0.4.15", path = "credential/cargo
 cargo-credential-wincred = { version = "0.4.15", path = "credential/cargo-credential-wincred" }
 cargo-platform = { path = "crates/cargo-platform", version = "0.3.0" }
 cargo-test-macro = { version = "0.4.4", path = "crates/cargo-test-macro" }
-cargo-test-support = { version = "0.7.5", path = "crates/cargo-test-support" }
+cargo-test-support = { version = "0.8.0", path = "crates/cargo-test-support" }
 cargo-util = { version = "0.2.22", path = "crates/cargo-util" }
 cargo-util-schemas = { version = "0.9.0", path = "crates/cargo-util-schemas" }
 cargo_metadata = "0.19.1"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cargo-test-support"
-version = "0.7.5"
+version = "0.8.0"
 edition.workspace = true
 rust-version = "1.87"  # MSRV:1
 license.workspace = true

crates/cargo-test-support/Cargo.toml

@@ -9,189 +9,7 @@
 //!
 //! These tests are all disabled on rust-lang/rust's CI, but run in Cargo's CI.
 
-use crate::{basic_manifest, main_file, project};
-use cargo_util::ProcessError;
 use std::env;
-use std::fmt::Write;
-use std::process::{Command, Output};
-use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Once;
-
-/// Whether or not the resulting cross binaries can run on the host.
-static CAN_RUN_ON_HOST: AtomicBool = AtomicBool::new(false);
-
-pub fn disabled() -> bool {
-    // First, disable if requested.
-    match env::var("CFG_DISABLE_CROSS_TESTS") {
-        Ok(ref s) if *s == "1" => return true,
-        _ => {}
-    }
-
-    // It requires setting `target.linker` for cross-compilation to work on aarch64,
-    // so not going to bother now.
-    if cfg!(all(target_arch = "aarch64", target_os = "linux")) {
-        return true;
-    }
-
-    // Cross tests are only tested to work on macos, linux, and MSVC windows.
-    if !(cfg!(target_os = "macos") || cfg!(target_os = "linux") || cfg!(target_env = "msvc")) {
-        return true;
-    }
-
-    // It's not particularly common to have a cross-compilation setup, so
-    // try to detect that before we fail a bunch of tests through no fault
-    // of the user.
-    static CAN_BUILD_CROSS_TESTS: AtomicBool = AtomicBool::new(false);
-    static CHECK: Once = Once::new();
-
-    let cross_target = alternate();
-
-    let run_cross_test = || -> anyhow::Result<Output> {
-        let p = project()
-            .at("cross_test")
-            .file("Cargo.toml", &basic_manifest("cross_test", "1.0.0"))
-            .file("src/main.rs", &main_file(r#""testing!""#, &[]))
-            .build();
-
-        let build_result = p
-            .cargo("build --target")
-            .arg(&cross_target)
-            .exec_with_output();
-
-        if build_result.is_ok() {
-            CAN_BUILD_CROSS_TESTS.store(true, Ordering::SeqCst);
-        }
-
-        let result = p
-            .cargo("run --target")
-            .arg(&cross_target)
-            .exec_with_output();
-
-        if result.is_ok() {
-            CAN_RUN_ON_HOST.store(true, Ordering::SeqCst);
-        }
-        build_result
-    };
-
-    CHECK.call_once(|| {
-        drop(run_cross_test());
-    });
-
-    if CAN_BUILD_CROSS_TESTS.load(Ordering::SeqCst) {
-        // We were able to compile a simple project, so the user has the
-        // necessary `std::` bits installed. Therefore, tests should not
-        // be disabled.
-        return false;
-    }
-
-    // We can't compile a simple cross project. We want to warn the user
-    // by failing a single test and having the remainder of the cross tests
-    // pass. We don't use `std::sync::Once` here because panicking inside its
-    // `call_once` method would poison the `Once` instance, which is not what
-    // we want.
-    static HAVE_WARNED: AtomicBool = AtomicBool::new(false);
-
-    if HAVE_WARNED.swap(true, Ordering::SeqCst) {
-        // We are some other test and somebody else is handling the warning.
-        // Just disable the current test.
-        return true;
-    }
-
-    // We are responsible for warning the user, which we do by panicking.
-    let mut message = format!(
-        "
-Cannot cross compile to {}.
-
-This failure can be safely ignored. If you would prefer to not see this
-failure, you can set the environment variable CFG_DISABLE_CROSS_TESTS to \"1\".
-
-Alternatively, you can install the necessary libraries to enable cross
-compilation tests. Cross compilation tests depend on your host platform.
-",
-        cross_target
-    );
-
-    if cfg!(target_os = "linux") {
-        message.push_str(
-            "
-Linux cross tests target i686-unknown-linux-gnu, which requires the ability to
-build and run 32-bit targets. This requires the 32-bit libraries to be
-installed. For example, on Ubuntu, run `sudo apt install gcc-multilib` to
-install the necessary libraries.
-",
-        );
-    } else if cfg!(all(target_os = "macos", target_arch = "aarch64")) {
-        message.push_str(
-            "
-macOS on aarch64 cross tests to target x86_64-apple-darwin.
-This should be natively supported via Xcode, nothing additional besides the
-rustup target should be needed.
-",
-        );
-    } else if cfg!(target_os = "macos") {
-        message.push_str(
-            "
-macOS on x86_64 cross tests to target x86_64-apple-ios, which requires the iOS
-SDK to be installed. This should be included with Xcode automatically. If you
-are using the Xcode command line tools, you'll need to install the full Xcode
-app (from the Apple App Store), and switch to it with this command:
-
-    sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
-
-Some cross-tests want to *run* the executables on the host. These tests will
-be ignored if this is not possible. On macOS, this means you need an iOS
-simulator installed to run these tests. To install a simulator, open Xcode, go
-to preferences > Components, and download the latest iOS simulator.
-",
-        );
-    } else if cfg!(target_os = "windows") {
-        message.push_str(
-            "
-Windows cross tests target i686-pc-windows-msvc, which requires the ability
-to build and run 32-bit targets. This should work automatically if you have
-properly installed Visual Studio build tools.
-",
-        );
-    } else {
-        // The check at the top should prevent this.
-        panic!("platform should have been skipped");
-    }
-
-    let rustup_available = Command::new("rustup").output().is_ok();
-    if rustup_available {
-        write!(
-            message,
-            "
-Make sure that the appropriate `rustc` target is installed with rustup:
-
-    rustup target add {}
-",
-            cross_target
-        )
-        .unwrap();
-    } else {
-        write!(
-            message,
-            "
-rustup does not appear to be installed. Make sure that the appropriate
-`rustc` target is installed for the target `{}`.
-",
-            cross_target
-        )
-        .unwrap();
-    }
-
-    // Show the actual error message.
-    match run_cross_test() {
-        Ok(_) => message.push_str("\nUh oh, second run succeeded?\n"),
-        Err(err) => match err.downcast_ref::<ProcessError>() {
-            Some(proc_err) => write!(message, "\nTest error: {}\n", proc_err).unwrap(),
-            None => write!(message, "\nUnexpected non-process error: {}\n", err).unwrap(),
-        },
-    }
-
-    panic!("{}", message);
-}
 
 /// The arch triple of the test-running host.
 pub fn native() -> &'static str {
@@ -252,31 +70,9 @@ pub fn unused() -> &'static str {
     "wasm32-unknown-unknown"
 }
 
-/// Whether or not the host can run cross-compiled executables.
-pub fn can_run_on_host() -> bool {
-    if disabled() {
-        return false;
-    }
-    // macos is currently configured to cross compile to x86_64-apple-ios
-    // which requires a simulator to run. Azure's CI image appears to have the
-    // SDK installed, but are not configured to launch iOS images with a
-    // simulator.
-    if cfg!(target_os = "macos") {
-        if CAN_RUN_ON_HOST.load(Ordering::SeqCst) {
-            return true;
-        } else {
-            println!("Note: Cannot run on host, skipping.");
-            return false;
-        }
-    } else {
-        assert!(CAN_RUN_ON_HOST.load(Ordering::SeqCst));
-        return true;
-    }
-}
-
 /// Check if the given target has been installed.
 ///
-/// Generally [`disabled`] should be used to check if cross-compilation is allowed.
+/// Generally `testsuite::utils::cross_compile::disabled` should be used to check if cross-compilation is allowed.
 /// And [`alternate`] to get the cross target.
 ///
 /// You should only use this as a last resort to skip tests,

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

@@ -110,13 +110,11 @@ pub mod install;
 pub mod paths;
 pub mod publish;
 pub mod registry;
-pub mod tools;
 
 pub mod prelude {
     pub use crate::cargo_test;
     pub use crate::paths::CargoPathExt;
     pub use crate::ArgLineCommandExt;
-    pub use crate::CargoCommandExt;
     pub use crate::ChannelChangerCommandExt;
     pub use crate::TestEnvCommandExt;
     pub use snapbox::IntoData;
@@ -491,28 +489,6 @@ impl Project {
         execs().with_process_builder(p)
     }
 
-    /// Creates a `ProcessBuilder` to run cargo.
-    ///
-    /// Arguments can be separated by spaces.
-    ///
-    /// For `cargo run`, see [`Project::rename_run`].
-    ///
-    /// # Example:
-    ///
-    /// ```no_run
-    /// # let p = cargo_test_support::project().build();
-    /// p.cargo("build --bin foo").run();
-    /// ```
-    pub fn cargo(&self, cmd: &str) -> Execs {
-        let cargo = cargo_exe();
-        let mut execs = self.process(&cargo);
-        if let Some(ref mut p) = execs.process_builder {
-            p.env("CARGO", cargo);
-            p.arg_line(cmd);
-        }
-        execs
-    }
-
     /// Safely run a process after `cargo build`.
     ///
     /// Windows has a problem where a process cannot be reliably
@@ -621,11 +597,6 @@ pub fn main_file(println: &str, externed_deps: &[&str]) -> String {
     buf
 }
 
-/// Path to the cargo binary
-pub fn cargo_exe() -> PathBuf {
-    snapbox::cmd::cargo_bin("cargo")
-}
-
 /// This is the raw output from the process.
 ///
 /// This is similar to `std::process::Output`, however the `status` is
@@ -643,8 +614,8 @@ pub struct RawOutput {
 ///
 /// Construct with
 /// - [`execs`]
-/// - [`cargo_process`]
 /// - [`Project`] methods
+/// - `cargo_process` in testsuite
 #[must_use]
 #[derive(Clone)]
 pub struct Execs {
@@ -1495,21 +1466,6 @@ impl TestEnvCommandExt for snapbox::cmd::Command {
     }
 }
 
-/// Test the cargo command
-pub trait CargoCommandExt {
-    fn cargo_ui() -> Self;
-}
-
-impl CargoCommandExt for snapbox::cmd::Command {
-    fn cargo_ui() -> Self {
-        Self::new(cargo_exe())
-            .with_assert(compare::assert_ui())
-            .env("CARGO_TERM_COLOR", "always")
-            .env("CARGO_TERM_HYPERLINKS", "true")
-            .test_env()
-    }
-}
-
 /// Add a list of arguments as a line
 pub trait ArgLineCommandExt: Sized {
     fn arg_line(mut self, s: &str) -> Self {
@@ -1547,15 +1503,6 @@ impl ArgLineCommandExt for snapbox::cmd::Command {
     }
 }
 
-/// Run `cargo $arg_line`, see [`Execs`]
-pub fn cargo_process(arg_line: &str) -> Execs {
-    let cargo = cargo_exe();
-    let mut p = process(&cargo);
-    p.env("CARGO", cargo);
-    p.arg_line(arg_line);
-    execs().with_process_builder(p)
-}
-
 /// Run `git $arg_line`, see [`ProcessBuilder`]
 pub fn git_process(arg_line: &str) -> ProcessBuilder {
     let mut p = process("git");

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

@@ -6,29 +6,6 @@
 //! # use cargo_test_support::registry::RegistryBuilder;
 //! # use cargo_test_support::publish::validate_upload;
 //! # use cargo_test_support::project;
-//! // This replaces `registry::init()` and must be called before `Package::new().publish()`
-//! let registry = RegistryBuilder::new().http_api().http_index().build();
-//!
-//! let p = project()
-//!     .file(
-//!         "Cargo.toml",
-//!         r#"
-//!             [package]
-//!             name = "foo"
-//!             version = "0.0.1"
-//!             edition = "2015"
-//!             authors = []
-//!             license = "MIT"
-//!             description = "foo"
-//!         "#,
-//!     )
-//!     .file("src/main.rs", "fn main() {}")
-//!     .build();
-//!
-//! p.cargo("publish --no-verify")
-//!     .replace_crates_io(registry.index_url())
-//!     .run();
-//!
 //! validate_upload(
 //!     r#"
 //!     {

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

@@ -39,7 +39,7 @@
 //!     "#)
 //!     .build();
 //!
-//! p.cargo("run").with_stdout_data(str!["24"]).run();
+//! // p.cargo("run").with_stdout_data(str!["24"]).run();
 //! ```
 
 use crate::git::repo;