Rollup merge of #146929 - Zalathar:capture, r=Kobzol,jieyouxu

compiletest: Remove old-output-capture and become a stage0 bootstrap tool

The new compiletest output-capture system became the default in rust-lang/rust#146574, and no problems have been reported since.

This PR therefore removes the old output-capture implementation from compiletest, and adjusts bootstrap to always build and test compiletest as a stage0 bootstrap tool.

In other words, compiletest no longer relies on any unstable features (such as `libtest` or `internal_output_capture`), and is now written entirely in stable Rust!

The compiletest self-tests still need access to an in-tree rustc, in order to obtain information via `rustc --print`, so we interpret `--stage` as indicating the stage of that secondary compiler, but always use the stage0 compiler to build compiletest itself.

r? Kobzol

3 files changed, 10 insertions, 66 deletions

diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index 6da102b1b5f..6d959948918 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -661,18 +661,10 @@ pub struct Config {
     pub builtin_cfg_names: OnceLock<HashSet<String>>,
     pub supported_crate_types: OnceLock<HashSet<String>>,
 
-    /// FIXME: this is why we still need to depend on *staged* `std`, it's because we currently rely
-    /// on `#![feature(internal_output_capture)]` for [`std::io::set_output_capture`] to implement
-    /// `libtest`-esque `--no-capture`.
-    ///
     /// FIXME: rename this to the more canonical `no_capture`, or better, invert this to `capture`
     /// to avoid `!nocapture` double-negatives.
     pub nocapture: bool,
 
-    /// True if the experimental new output-capture implementation should be
-    /// used, avoiding the need for `#![feature(internal_output_capture)]`.
-    pub new_output_capture: bool,
-
     /// Needed both to construct [`build_helper::git::GitConfig`].
     pub nightly_branch: String,
     pub git_merge_commit_email: String,
@@ -790,7 +782,6 @@ impl Config {
             builtin_cfg_names: Default::default(),
             supported_crate_types: Default::default(),
             nocapture: Default::default(),
-            new_output_capture: Default::default(),
             nightly_branch: Default::default(),
             git_merge_commit_email: Default::default(),
             profiler_runtime: Default::default(),
diff --git a/src/tools/compiletest/src/executor.rs b/src/tools/compiletest/src/executor.rs
index c8e13d44573..c7aca6d1c5a 100644
--- a/src/tools/compiletest/src/executor.rs
+++ b/src/tools/compiletest/src/executor.rs
@@ -9,8 +9,8 @@ use std::borrow::Cow;
 use std::collections::HashMap;
 use std::hash::{BuildHasherDefault, DefaultHasher};
 use std::num::NonZero;
-use std::sync::{Arc, Mutex, mpsc};
-use std::{env, hint, io, mem, panic, thread};
+use std::sync::{Arc, mpsc};
+use std::{env, hint, mem, panic, thread};
 
 use camino::Utf8PathBuf;
 
@@ -130,10 +130,6 @@ fn run_test_inner(
         panic_hook::set_capture_buf(Default::default());
     }
 
-    if let CaptureKind::Old { ref buf } = capture {
-        io::set_output_capture(Some(Arc::clone(buf)));
-    }
-
     let stdout = capture.stdout();
     let stderr = capture.stderr();
 
@@ -144,9 +140,6 @@ fn run_test_inner(
         // Forward any captured panic message to (captured) stderr.
         write!(stderr, "{panic_buf}");
     }
-    if matches!(capture, CaptureKind::Old { .. }) {
-        io::set_output_capture(None);
-    }
 
     let outcome = match (should_panic, panic_payload) {
         (ShouldPanic::No, None) | (ShouldPanic::Yes, Some(_)) => TestOutcome::Succeeded,
@@ -167,31 +160,24 @@ enum CaptureKind {
     /// runners, whose output is always captured.)
     None,
 
-    /// Use the old output-capture implementation, which relies on the unstable
-    /// library feature `#![feature(internal_output_capture)]`.
-    Old { buf: Arc<Mutex<Vec<u8>>> },
-
-    /// Use the new output-capture implementation, which only uses stable Rust.
-    New { buf: output_capture::CaptureBuf },
+    /// Capture all console output that would be printed by test runners via
+    /// their `stdout` and `stderr` trait objects, or via the custom panic hook.
+    Capture { buf: output_capture::CaptureBuf },
 }
 
 impl CaptureKind {
     fn for_config(config: &Config) -> Self {
         if config.nocapture {
             Self::None
-        } else if config.new_output_capture {
-            Self::New { buf: output_capture::CaptureBuf::new() }
         } else {
-            // Create a capure buffer for `io::set_output_capture`.
-            Self::Old { buf: Default::default() }
+            Self::Capture { buf: output_capture::CaptureBuf::new() }
         }
     }
 
     fn should_set_panic_hook(&self) -> bool {
         match self {
             Self::None => false,
-            Self::Old { .. } => true,
-            Self::New { .. } => true,
+            Self::Capture { .. } => true,
         }
     }
 
@@ -205,16 +191,15 @@ impl CaptureKind {
 
     fn capture_buf_or<'a>(&'a self, fallback: &'a dyn ConsoleOut) -> &'a dyn ConsoleOut {
         match self {
-            Self::None | Self::Old { .. } => fallback,
-            Self::New { buf } => buf,
+            Self::None => fallback,
+            Self::Capture { buf } => buf,
         }
     }
 
     fn into_inner(self) -> Option<Vec<u8>> {
         match self {
             Self::None => None,
-            Self::Old { buf } => Some(buf.lock().unwrap_or_else(|e| e.into_inner()).to_vec()),
-            Self::New { buf } => Some(buf.into_inner().into()),
+            Self::Capture { buf } => Some(buf.into_inner().into()),
         }
     }
 }
diff --git a/src/tools/compiletest/src/lib.rs b/src/tools/compiletest/src/lib.rs
index ce2a3d4b5fb..15e31dadf97 100644
--- a/src/tools/compiletest/src/lib.rs
+++ b/src/tools/compiletest/src/lib.rs
@@ -1,9 +1,4 @@
 #![crate_name = "compiletest"]
-// Needed by the "new" test executor that does not depend on libtest.
-// FIXME(Zalathar): We should be able to get rid of `internal_output_capture`,
-// by having `runtest` manually capture all of its println-like output instead.
-// That would result in compiletest being written entirely in stable Rust!
-#![feature(internal_output_capture)]
 
 #[cfg(test)]
 mod tests;
@@ -178,12 +173,6 @@ pub fn parse_config(args: Vec<String>) -> Config {
         // FIXME: Temporarily retained so we can point users to `--no-capture`
         .optflag("", "nocapture", "")
         .optflag("", "no-capture", "don't capture stdout/stderr of tests")
-        .optopt(
-            "N",
-            "new-output-capture",
-            "enables or disables the new output-capture implementation",
-            "off|on",
-        )
         .optflag("", "profiler-runtime", "is the profiler runtime enabled for this target")
         .optflag("h", "help", "show this message")
         .reqopt("", "channel", "current Rust channel", "CHANNEL")
@@ -480,14 +469,6 @@ pub fn parse_config(args: Vec<String>) -> Config {
         supported_crate_types: OnceLock::new(),
 
         nocapture: matches.opt_present("no-capture"),
-        new_output_capture: {
-            let value = matches
-                .opt_str("new-output-capture")
-                .or_else(|| env::var("COMPILETEST_NEW_OUTPUT_CAPTURE").ok())
-                .unwrap_or_else(|| "on".to_owned());
-            parse_bool_option(&value)
-                .unwrap_or_else(|| panic!("unknown `--new-output-capture` value `{value}` given"))
-        },
 
         nightly_branch: matches.opt_str("nightly-branch").unwrap(),
         git_merge_commit_email: matches.opt_str("git-merge-commit-email").unwrap(),
@@ -503,19 +484,6 @@ pub fn parse_config(args: Vec<String>) -> Config {
     }
 }
 
-/// Parses the same set of boolean values accepted by rustc command-line arguments.
-///
-/// Accepting all of these values is more complicated than just picking one
-/// pair, but has the advantage that contributors who are used to rustc
-/// shouldn't have to think about which values are legal.
-fn parse_bool_option(value: &str) -> Option<bool> {
-    match value {
-        "off" | "no" | "n" | "false" => Some(false),
-        "on" | "yes" | "y" | "true" => Some(true),
-        _ => None,
-    }
-}
-
 pub fn opt_str(maybestr: &Option<String>) -> &str {
     match *maybestr {
         None => "(none)",