Auto merge of #128245 - Oneirical:total-linkage-ownage, r=<try>

Migrate `cdylib-dylib-linkage` `run-make` test to rmake

Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).

~~Those sysroot tests are always fun. I'm getting local errors that don't make a lot of sense about my own sysroot not existing, so I am trying this in CI to see what happens.~~

~~EDIT: I am getting the same error here. The strange thing is, when I try to navigate to `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib` on my personal computer, the directory does exist, but the error message is that the directory does not.~~

EDIT 2: The sysroot path just needed to be trimmed!

Please try:

// try-job: x86_64-msvc // passed previously
try-job: x86_64-mingw
try-job: x86_64-gnu-llvm-18
try-job: i686-msvc
try-job: aarch64-apple

src/tools/run-make-support/src/lib.rs

@@ -76,8 +76,8 @@ pub use artifact_names::{
 
 /// Path-related helpers.
 pub use path_helpers::{
-    cwd, filename_not_in_denylist, has_extension, has_prefix, has_suffix, not_contains, path,
-    shallow_find_files, source_root,
+    cwd, filename_not_in_denylist, has_extension, has_prefix, has_suffix, name_contains,
+    not_contains, path, shallow_find_files, source_root,
 };
 
 /// Helpers for scoped test execution where certain properties are attempted to be maintained.

src/tools/run-make-support/src/path_helpers.rs

@@ -3,6 +3,7 @@
 use std::path::{Path, PathBuf};
 
 use crate::env::env_var;
+use crate::rfs;
 
 /// Return the current working directory.
 ///
@@ -40,7 +41,7 @@ pub fn shallow_find_files<P: AsRef<Path>, F: Fn(&PathBuf) -> bool>(
     filter: F,
 ) -> Vec<PathBuf> {
     let mut matching_files = Vec::new();
-    for entry in std::fs::read_dir(path).unwrap() {
+    for entry in rfs::read_dir(path) {
         let entry = entry.expect("failed to read directory entry.");
         let path = entry.path();
 
@@ -78,3 +79,8 @@ pub fn has_extension<P: AsRef<Path>>(path: P, extension: &str) -> bool {
 pub fn has_suffix<P: AsRef<Path>>(path: P, suffix: &str) -> bool {
     path.as_ref().file_name().is_some_and(|name| name.to_str().unwrap().ends_with(suffix))
 }
+
+/// Returns true if the filename at `path` contains `needle`.
+pub fn name_contains<P: AsRef<Path>>(path: P, needle: &str) -> bool {
+    path.as_ref().file_name().is_some_and(|name| name.to_str().unwrap().contains(needle))
+}

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -1,6 +1,5 @@
 run-make/branch-protection-check-IBT/Makefile
 run-make/cat-and-grep-sanity-check/Makefile
-run-make/cdylib-dylib-linkage/Makefile
 run-make/cross-lang-lto-clang/Makefile
 run-make/cross-lang-lto-pgo-smoketest/Makefile
 run-make/cross-lang-lto-upstream-rlibs/Makefile

tests/run-make/cdylib-dylib-linkage/rmake.rs

@@ -0,0 +1,40 @@
+// Previously, rustc mandated that cdylibs could only link against rlibs as dependencies,
+// making linkage between cdylibs and dylibs impossible. After this was changed in #68448,
+// this test attempts to link both `foo` (a cdylib) and `bar` (a dylib) and checks that
+// both compilation and execution are successful.
+// See https://github.com/rust-lang/rust/pull/68448
+
+//@ ignore-cross-compile
+// Reason: the compiled binary is executed
+
+use run_make_support::{
+    bin_name, cc, dynamic_lib_name, has_extension, has_prefix, has_suffix, is_msvc, name_contains,
+    path, run, rustc, shallow_find_files, target,
+};
+
+fn main() {
+    rustc().arg("-Cprefer-dynamic").input("bar.rs").run();
+    rustc().input("foo.rs").run();
+    let sysroot = rustc().print("sysroot").run().stdout_utf8();
+    let sysroot = sysroot.trim();
+    let target_sysroot = path(sysroot).join("lib/rustlib").join(target()).join("lib");
+    if is_msvc() {
+        let mut libs = shallow_find_files(&target_sysroot, |path| {
+            has_prefix(path, "libstd-") && has_suffix(path, ".dll.lib")
+        });
+        libs.push(path("foo.dll.lib"));
+        libs.push(path("bar.dll.lib"));
+        cc().input("foo.c").args(&libs).out_exe("foo").run();
+    } else {
+        let stdlibs = shallow_find_files(&target_sysroot, |path| {
+            !has_extension(path, "rlib") && name_contains(path, "std")
+        });
+        cc().input("foo.c")
+            .args(&[dynamic_lib_name("foo"), dynamic_lib_name("bar")])
+            .arg(stdlibs.get(0).unwrap())
+            .library_search_path(&target_sysroot)
+            .output(bin_name("foo"))
+            .run();
+    }
+    run("foo");
+}