[PATCH v2] rust: macros: fix `make rusttest` build on macOS

[Tamir Duberstein]

Do not emit `#[link_section = ".modinfo"]` on macOS (i.e. when building
userspace tests); .modinfo is not a legal section specifier in mach-o.

Before this change tests failed to compile:

  ---- ../rust/macros/lib.rs - module (line 66) stdout ----
  rustc-LLVM ERROR: Global variable '_ZN8rust_out13__module_init13__module_init27__MY_DEVICE_DRIVER_MODULE_017h141f80536770e0d4E' has an invalid section specifier '.modinfo': mach-o section specifier requires a segment and section separated by a comma.
  Couldn't compile the test.
  ---- ../rust/macros/lib.rs - module (line 33) stdout ----
  rustc-LLVM ERROR: Global variable '_ZN8rust_out13__module_init13__module_init20__MY_KERNEL_MODULE_017h5d79189564b41e07E' has an invalid section specifier '.modinfo': mach-o section specifier requires a segment and section separated by a comma.
  Couldn't compile the test.

Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx>
---
Changes in v2:
- Drop patch: "rust: macros: improve panic messages".
- Rebase on v6.14-rc2.
- Link to v1: https://lore.kernel.org/r/20250207-macros-section-v1-0-8f018cb05a20@xxxxxxxxx
---
 rust/macros/module.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index cdf94f4982df..56f746be4ab7 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -56,7 +56,7 @@ fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
             "
                 {cfg}
                 #[doc(hidden)]
-                #[link_section = \".modinfo\"]
+                #[cfg_attr(not(target_os = \"macos\"), link_section = \".modinfo\")]
                 #[used]
                 pub static __{module}_{counter}: [u8; {length}] = *{string};
             ",

---
base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
change-id: 20250207-macros-section-f7cddc7bbdea

Best regards,
-- 
Tamir Duberstein <tamird@xxxxxxxxx>