From 80408e0649b29915ad5258367b67c70a91e6b043 Mon Sep 17 00:00:00 2001
From: Oneirical <manchot@videotron.ca>
Date: Tue, 28 May 2024 13:21:28 -0400
Subject: [PATCH] port symlinked-extern to rmake

---
 src/tools/run-make-support/src/lib.rs         | 23 +++++++++++++++--
 .../tidy/src/allowed_run_make_makefiles.txt   |  1 -
 tests/run-make/symlinked-extern/rmake.rs      | 25 +++++++++++++++++++
 3 files changed, 46 insertions(+), 3 deletions(-)
 create mode 100644 tests/run-make/symlinked-extern/rmake.rs

diff --git a/src/tools/run-make-support/src/lib.rs b/src/tools/run-make-support/src/lib.rs
index b920f9a07db..d93a950d3e1 100644
--- a/src/tools/run-make-support/src/lib.rs
+++ b/src/tools/run-make-support/src/lib.rs
@@ -93,6 +93,17 @@ pub fn source_root() -> PathBuf {
     env_var("SOURCE_ROOT").into()
 }
 
+/// Creates a new symlink to a path on the filesystem, adjusting for Windows or Unix.
+pub fn create_symlink<P: AsRef<Path>, Q: AsRef<Path>>(original: P, link: Q) {
+    if is_windows() {
+        use std::os::windows::fs;
+        fs::symlink_file(original, link).unwrap();
+    } else {
+        use std::os::unix::fs;
+        fs::symlink(original, link).unwrap();
+    }
+}
+
 /// Construct the static library name based on the platform.
 pub fn static_lib_name(name: &str) -> String {
     // See tools.mk (irrelevant lines omitted):
@@ -114,7 +125,11 @@ pub fn static_lib_name(name: &str) -> String {
     // ```
     assert!(!name.contains(char::is_whitespace), "static library name cannot contain whitespace");
 
-    if is_msvc() { format!("{name}.lib") } else { format!("lib{name}.a") }
+    if is_msvc() {
+        format!("{name}.lib")
+    } else {
+        format!("lib{name}.a")
+    }
 }
 
 /// Construct the dynamic library name based on the platform.
@@ -161,7 +176,11 @@ pub fn rust_lib_name(name: &str) -> String {
 
 /// Construct the binary name based on platform.
 pub fn bin_name(name: &str) -> String {
-    if is_windows() { format!("{name}.exe") } else { name.to_string() }
+    if is_windows() {
+        format!("{name}.exe")
+    } else {
+        name.to_string()
+    }
 }
 
 /// Return the current working directory.
diff --git a/src/tools/tidy/src/allowed_run_make_makefiles.txt b/src/tools/tidy/src/allowed_run_make_makefiles.txt
index ac89a30f353..4adfd52b2b3 100644
--- a/src/tools/tidy/src/allowed_run_make_makefiles.txt
+++ b/src/tools/tidy/src/allowed_run_make_makefiles.txt
@@ -228,7 +228,6 @@ run-make/std-core-cycle/Makefile
 run-make/symbol-mangling-hashed/Makefile
 run-make/symbol-visibility/Makefile
 run-make/symbols-include-type-name/Makefile
-run-make/symlinked-extern/Makefile
 run-make/symlinked-libraries/Makefile
 run-make/symlinked-rlib/Makefile
 run-make/sysroot-crates-are-unstable/Makefile
diff --git a/tests/run-make/symlinked-extern/rmake.rs b/tests/run-make/symlinked-extern/rmake.rs
new file mode 100644
index 00000000000..124f1cef849
--- /dev/null
+++ b/tests/run-make/symlinked-extern/rmake.rs
@@ -0,0 +1,25 @@
+// Crates that are resolved normally have their path canonicalized and all
+// symlinks resolved. This did not happen for paths specified
+// using the --extern option to rustc, which could lead to rustc thinking
+// that it encountered two different versions of a crate, when it's
+// actually the same version found through different paths.
+
+// This test checks that --extern and symlinks together
+// can result in successful compilation.
+
+//@ ignore-cross-compile
+
+use run_make_support::{create_symlink, rustc, tmp_dir};
+use std::fs;
+
+fn main() {
+    rustc().input("foo.rs").run();
+    fs::create_dir_all(tmp_dir().join("other")).unwrap();
+    create_symlink(tmp_dir().join("libfoo.rlib"), tmp_dir().join("other"));
+    rustc().input("bar.rs").library_search_path(tmp_dir()).run();
+    rustc()
+        .input("baz.rs")
+        .extern_("foo", tmp_dir().join("other/libfoo.rlib"))
+        .library_search_path(tmp_dir())
+        .run();
+}