Add __isOSVersionAtLeast and __isPlatformVersionAtLeast symbols

Allows users to link to Objective-C code using `@available(...)`.

3 files changed, 43 insertions, 0 deletions

diff --git a/tests/run-make/apple-c-available-links/foo.c b/tests/run-make/apple-c-available-links/foo.c
new file mode 100644
index 00000000000..eff99a8b12a
--- /dev/null
+++ b/tests/run-make/apple-c-available-links/foo.c
@@ -0,0 +1,22 @@
+int foo(void) {
+    // Act as if using some API that's a lot newer than the deployment target.
+    //
+    // This forces Clang to insert a call to __isPlatformVersionAtLeast,
+    // and linking will fail if that is not present.
+    if (__builtin_available(
+        macos 1000.0,
+        ios 1000.0,
+        tvos 1000.0,
+        watchos 1000.0,
+        // CI runs below Xcode 15, where `visionos` wasn't a valid key in
+        // `__builtin_available`.
+#ifdef TARGET_OS_VISION
+        visionos 1000.0,
+#endif
+        *
+    )) {
+        return 1;
+    } else {
+        return 0;
+    }
+}
diff --git a/tests/run-make/apple-c-available-links/main.rs b/tests/run-make/apple-c-available-links/main.rs
new file mode 100644
index 00000000000..4ffada43c1b
--- /dev/null
+++ b/tests/run-make/apple-c-available-links/main.rs
@@ -0,0 +1,7 @@
+unsafe extern "C" {
+    safe fn foo() -> core::ffi::c_int;
+}
+
+fn main() {
+    assert_eq!(foo(), 0);
+}
diff --git a/tests/run-make/apple-c-available-links/rmake.rs b/tests/run-make/apple-c-available-links/rmake.rs
new file mode 100644
index 00000000000..44a5ee94d57
--- /dev/null
+++ b/tests/run-make/apple-c-available-links/rmake.rs
@@ -0,0 +1,14 @@
+//! Test that using `__builtin_available` in C (`@available` in Objective-C)
+//! successfully links (because `std` provides the required symbols).
+
+//@ only-apple __builtin_available is (mostly) specific to Apple platforms.
+
+use run_make_support::{cc, rustc, target};
+
+fn main() {
+    // Invoke the C compiler to generate an object file.
+    cc().arg("-c").input("foo.c").output("foo.o").run();
+
+    // Link the object file together with a Rust program.
+    rustc().target(target()).input("main.rs").link_arg("foo.o").run();
+}