Rollup merge of #126862 - ChrisDenton:needs-symlink, r=jieyouxu

Add needs-symlink directive to compiletest

This is an alternative to #126846 that allows running symlink tests on Windows in CI but will ignore them locally if symlinks aren't available. A future improvement would be to check that the `needs-symlink` directive is used in rmake files that call `create_symlink` but this is just a quick PR to unblock Windows users who want to run tests locally without enabling symlinks.

src/tools/compiletest/src/header.rs

@@ -877,6 +877,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "needs-sanitizer-shadow-call-stack",
     "needs-sanitizer-support",
     "needs-sanitizer-thread",
+    "needs-symlink",
     "needs-threads",
     "needs-unwind",
     "needs-wasmtime",

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

@@ -144,6 +144,11 @@ pub(super) fn handle_needs(
             condition: config.runner.as_ref().is_some_and(|r| r.contains("wasmtime")),
             ignore_reason: "ignored when wasmtime runner is not available",
         },
+        Need {
+            name: "needs-symlink",
+            condition: cache.symlinks,
+            ignore_reason: "ignored if symlinks are unavailable",
+        },
     ];
 
     let (name, comment) = match ln.split_once([':', ' ']) {
@@ -209,6 +214,7 @@ pub(super) struct CachedNeedsConditions {
     xray: bool,
     rust_lld: bool,
     dlltool: bool,
+    symlinks: bool,
 }
 
 impl CachedNeedsConditions {
@@ -253,6 +259,7 @@ impl CachedNeedsConditions {
                 .exists(),
 
             dlltool: find_dlltool(&config),
+            symlinks: has_symlinks(),
         }
     }
 }
@@ -279,3 +286,22 @@ fn find_dlltool(config: &Config) -> bool {
     };
     dlltool_found
 }
+
+#[cfg(windows)]
+fn has_symlinks() -> bool {
+    if std::env::var_os("CI").is_some() {
+        return true;
+    }
+    let link = std::env::temp_dir().join("RUST_COMPILETEST_SYMLINK_CHECK");
+    if std::os::windows::fs::symlink_file("DOES NOT EXIST", &link).is_ok() {
+        std::fs::remove_file(&link).unwrap();
+        true
+    } else {
+        false
+    }
+}
+
+#[cfg(not(windows))]
+fn has_symlinks() -> bool {
+    true
+}

tests/run-make/symlinked-extern/rmake.rs

@@ -9,6 +9,7 @@
 // can result in successful compilation.
 
 //@ ignore-cross-compile
+//@ needs-symlink
 
 use run_make_support::{create_symlink, cwd, fs_wrapper, rustc};
 

tests/run-make/symlinked-libraries/rmake.rs

@@ -6,6 +6,7 @@
 // See https://github.com/rust-lang/rust/issues/12459
 
 //@ ignore-cross-compile
+//@ needs-symlink
 
 use run_make_support::{create_symlink, dynamic_lib_name, fs_wrapper, rustc};
 

tests/run-make/symlinked-rlib/rmake.rs

@@ -6,6 +6,7 @@
 // See https://github.com/rust-lang/rust/pull/32828
 
 //@ ignore-cross-compile
+//@ needs-symlink
 
 use run_make_support::{create_symlink, cwd, rustc};