From 339616b97afbd3b84c9fd5054f5cb8f7bbcfd249 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=AE=B8=E6=9D=B0=E5=8F=8B=20Jieyou=20Xu=20=28Joe=29?=
 <39484203+jieyouxu@users.noreply.github.com>
Date: Thu, 23 Jan 2025 14:38:43 +0800
Subject: [PATCH] compiletest: implement `needs-subprocess` directive

---
 src/tools/compiletest/src/common.rs         | 11 +++++++++++
 src/tools/compiletest/src/directive-list.rs |  1 +
 src/tools/compiletest/src/header/needs.rs   |  8 ++++++++
 3 files changed, 20 insertions(+)

diff --git a/src/tools/compiletest/src/common.rs b/src/tools/compiletest/src/common.rs
index c6f3d7c0d108..00821fc9f9db 100644
--- a/src/tools/compiletest/src/common.rs
+++ b/src/tools/compiletest/src/common.rs
@@ -488,6 +488,17 @@ impl Config {
             git_merge_commit_email: &self.git_merge_commit_email,
         }
     }
+
+    pub fn has_subprocess_support(&self) -> bool {
+        // FIXME(#135928): compiletest is always a **host** tool. Building and running an
+        // capability detection executable against the **target** is not trivial. The short term
+        // solution here is to hard-code some targets to allow/deny, unfortunately.
+
+        let unsupported_target = self.target_cfg().env == "sgx"
+            || matches!(self.target_cfg().arch.as_str(), "wasm32" | "wasm64")
+            || self.target_cfg().os == "emscripten";
+        !unsupported_target
+    }
 }
 
 /// Known widths of `target_has_atomic`.
diff --git a/src/tools/compiletest/src/directive-list.rs b/src/tools/compiletest/src/directive-list.rs
index 5784cd831196..acdb3cbdd459 100644
--- a/src/tools/compiletest/src/directive-list.rs
+++ b/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",
diff --git a/src/tools/compiletest/src/header/needs.rs b/src/tools/compiletest/src/header/needs.rs
index e19dcd992fc2..12f0790fb104 100644
--- a/src/tools/compiletest/src/header/needs.rs
+++ b/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: config.has_subprocess_support(),
+            ignore_reason: "ignored on targets without subprocess support",
+        },
         Need {
             name: "needs-unwind",
             condition: config.can_unwind(),
@@ -351,6 +356,9 @@ fn find_dlltool(config: &Config) -> bool {
     dlltool_found
 }
 
+// FIXME(#135928): this is actually not quite right because this detection is run on the **host**.
+// This however still helps the case of windows -> windows local development in case symlinks are
+// not available.
 #[cfg(windows)]
 fn has_symlinks() -> bool {
     if std::env::var_os("CI").is_some() {