Auto merge of rust-lang#135926 - jieyouxu:needs-subprocess-thread, r=<try>

Implement `needs-subprocess` directive, and cleanup a bunch of tests to use `needs-{subprocess,threads}

### Summary

- Implements `//@ needs-subprocess` directive in compiletest.
- Documents `//@ needs-subprocess` in rustc-dev-guide.
- Replace `ignore-{wasm,wasm32,emscripten,sgx}` with `needs-{subprocess,threads}` where suitable in tests.
- Some drive-by test changes as I was trying to figure out if I could use `needs-{subprocess,threads}` and found some bits needlessly distracting.

Count of tests that use `ignore-{wasm,wasm32,emscripten,sgx}` before and after this PR:

| State | `ignore-sgx` | `ignore-wasm` | `ignore-emscripten` |
| - | - | - | - |
| Before this PR | 96 | 88 | 207 |
| After this PR | 36 | 38 | 61 |

<details>
<summary>Commands used to find out locally</summary>

```
--- before

[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-sgx" tests | wc -l
96
[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-wasm" tests | wc -l
88
[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-emscripten" tests | wc -l
207

--- after

[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-sgx" tests | wc -l
36
[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-wasm" tests | wc -l
38
[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-emscripten" tests | wc -l
61
```
</details>

### Review advice

- Best reviewed commit-by-commit.
- Non-trivial test changes (not mechanically simple replacements) are split into individual commits to help with review.
- I *could* split some test changes out into another PR, but I found that I needed to change some tests to `needs-threads`, some to `needs-subprocess`, and some needed to use *both*, so they might conflict and become very annoying.

---

r? `@ghost` (need to run try jobs)

try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: i686-mingw
try-job: x86_64-mingw-1
try-job: x86_64-apple-1
try-job: aarch64-apple
try-job: aarch64-gnu
try-job: test-various
try-job: armhf-gnu

Author: bors

src/doc/rustc-dev-guide/src/tests/directives.md

@@ -94,7 +94,7 @@ for more details.
 | Directive                         | Explanation                                                                                                              | Supported test suites                        | Possible values                                                                         |
 |-----------------------------------|--------------------------------------------------------------------------------------------------------------------------|----------------------------------------------|-----------------------------------------------------------------------------------------|
 | `check-run-results`               | Check run test binary `run-{pass,fail}` output snapshot                                                                  | `ui`, `crashes`, `incremental` if `run-pass` | N/A                                                                                     |
-| `error-pattern`                   | Check that output contains a specific string                                                                             | `ui`, `crashes`, `incremental` if `run-pass` | String                                                                                   |
+| `error-pattern`                   | Check that output contains a specific string                                                                             | `ui`, `crashes`, `incremental` if `run-pass` | String                                                                                  |
 | `regex-error-pattern`             | Check that output contains a regex pattern                                                                               | `ui`, `crashes`, `incremental` if `run-pass` | Regex                                                                                   |
 | `check-stdout`                    | Check `stdout` against `error-pattern`s from running test binary[^check_stdout]                                          | `ui`, `crashes`, `incremental`               | N/A                                                                                     |
 | `normalize-stderr-32bit`          | Normalize actual stderr (for 32-bit platforms) with a rule `"<raw>" -> "<normalized>"` before comparing against snapshot | `ui`, `incremental`                          | `"<RAW>" -> "<NORMALIZED>"`, `<RAW>`/`<NORMALIZED>` is regex capture and replace syntax |
@@ -176,6 +176,7 @@ settings:
 - `needs-rust-lld` — ignores if the rust lld support is not enabled (`rust.lld =
   true` in `config.toml`)
 - `needs-threads` — ignores if the target does not have threading support
+- `needs-subprocess`  — ignores if the target does not have subprocess support
 - `needs-symlink` — ignores if the target does not support symlinks. This can be
   the case on Windows if the developer did not enable privileged symlink
   permissions.

src/tools/compiletest/src/directive-list.rs

@@ -152,6 +152,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "needs-sanitizer-support",
     "needs-sanitizer-thread",
     "needs-std-debug-assertions",
+    "needs-subprocess",
     "needs-symlink",
     "needs-target-has-atomic",
     "needs-threads",

src/tools/compiletest/src/header/needs.rs

@@ -94,6 +94,11 @@ pub(super) fn handle_needs(
             condition: config.has_threads(),
             ignore_reason: "ignored on targets without threading support",
         },
+        Need {
+            name: "needs-subprocess",
+            condition: cache.subprocess,
+            ignore_reason: "ignored on targets without subprocess support",
+        },
         Need {
             name: "needs-unwind",
             condition: config.can_unwind(),
@@ -279,6 +284,7 @@ pub(super) struct CachedNeedsConditions {
     symlinks: bool,
     /// Whether LLVM built with zstd, for the `needs-llvm-zstd` directive.
     llvm_zstd: bool,
+    subprocess: bool,
 }
 
 impl CachedNeedsConditions {
@@ -324,6 +330,7 @@ impl CachedNeedsConditions {
             llvm_zstd: llvm_has_libzstd(&config),
             dlltool: find_dlltool(&config),
             symlinks: has_symlinks(),
+            subprocess: has_subprocess(),
         }
     }
 }
@@ -369,3 +376,9 @@ fn has_symlinks() -> bool {
 fn has_symlinks() -> bool {
     true
 }
+
+fn has_subprocess() -> bool {
+    std::process::Command::new("/does/not/exist")
+        .output()
+        .is_err_and(|e| e.kind() != std::io::ErrorKind::Unsupported)
+}

tests/ui/abi/homogenous-floats-target-feature-mixup.rs

@@ -5,8 +5,7 @@
 // without #[repr(simd)]
 
 //@ run-pass
-//@ ignore-wasm32 no processes
-//@ ignore-sgx no processes
+//@ needs-subprocess
 
 #![feature(avx512_target_feature)]
 

tests/ui/abi/segfault-no-out-of-stack.rs

@@ -1,6 +1,5 @@
 //@ run-pass
-//@ ignore-wasm32 can't run commands
-//@ ignore-sgx no processes
+//@ needs-subprocess
 //@ ignore-fuchsia must translate zircon signal to SIGSEGV/SIGBUS, FIXME (#58590)
 
 #![feature(rustc_private)]

tests/ui/abi/stack-probes-lto.rs

@@ -3,7 +3,7 @@
 //@[aarch64] only-aarch64
 //@[x32] only-x86
 //@[x64] only-x86_64
-//@ ignore-sgx no processes
+//@ needs-subprocess
 //@ ignore-musl FIXME #31506
 //@ ignore-fuchsia no exception handler registered for segfault
 //@ compile-flags: -C lto

tests/ui/abi/stack-probes.rs

@@ -3,8 +3,7 @@
 //@[aarch64] only-aarch64
 //@[x32] only-x86
 //@[x64] only-x86_64
-//@ ignore-emscripten no processes
-//@ ignore-sgx no processes
+//@ needs-subprocess
 //@ ignore-fuchsia no exception handler registered for segfault
 //@ ignore-nto Crash analysis impossible at SIGSEGV in QNX Neutrino
 //@ ignore-ios Stack probes are enabled, but the SIGSEGV handler isn't

tests/ui/alloc-error/default-alloc-error-hook.rs

@@ -1,6 +1,5 @@
 //@ run-pass
-//@ ignore-wasm32 no processes
-//@ ignore-sgx no processes
+//@ needs-subprocess
 
 use std::alloc::{Layout, handle_alloc_error};
 use std::env;

tests/ui/array-slice-vec/bounds-check-no-overflow.rs

@@ -1,6 +1,6 @@
 //@ run-fail
 //@ error-pattern:index out of bounds
-//@ ignore-emscripten no processes
+//@ needs-subprocess
 
 use std::mem::size_of;
 

tests/ui/array-slice-vec/box-of-array-of-drop-1.rs

@@ -1,12 +1,12 @@
 //@ run-pass
 //@ needs-unwind
+//@ needs-threads
+
 #![allow(overflowing_literals)]
 
 // Test that we cleanup a fixed size Box<[D; k]> properly when D has a
 // destructor.
 
-//@ ignore-emscripten no threads support
-
 use std::thread;
 use std::sync::atomic::{AtomicUsize, Ordering};