pass --gc-sections if -Zexport-executable-symbols is enabled and improve tests

Author: usamoi

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2542,12 +2542,9 @@ fn add_order_independent_options(
         // sections to ensure we have all the data for PGO.
         let keep_metadata =
             crate_type == CrateType::Dylib || sess.opts.cg.profile_generate.enabled();
-        if crate_type != CrateType::Executable || !sess.opts.unstable_opts.export_executable_symbols
-        {
-            cmd.gc_sections(keep_metadata);
-        } else {
-            cmd.no_gc_sections();
-        }
+        cmd.gc_sections(keep_metadata);
+    } else {
+        cmd.no_gc_sections();
     }
 
     cmd.set_output_kind(link_output_kind, crate_type, out_filename);

tests/run-make/export-executable-symbols/rmake.rs

@@ -4,20 +4,21 @@
 // symbol.
 // See https://github.com/rust-lang/rust/pull/85673
 
-//@ only-unix
-// Reason: the export-executable-symbols flag only works on Unix
-// due to hardcoded platform-specific implementation
-// (See #85673)
-//@ ignore-cross-compile
 //@ ignore-wasm
 
-use run_make_support::{bin_name, llvm_readobj, rustc};
+use run_make_support::object::Object;
+use run_make_support::{bin_name, is_darwin, object, rustc};
 
 fn main() {
-    rustc().arg("-Zexport-executable-symbols").input("main.rs").crate_type("bin").run();
-    llvm_readobj()
-        .symbols()
-        .input(bin_name("main"))
-        .run()
-        .assert_stdout_contains("exported_symbol");
+    rustc()
+        .arg("-Ctarget-feature=-crt-static")
+        .arg("-Zexport-executable-symbols")
+        .input("main.rs")
+        .crate_type("bin")
+        .run();
+    let name: &[u8] = if is_darwin() { b"_exported_symbol" } else { b"exported_symbol" };
+    let contents = std::fs::read(bin_name("main")).unwrap();
+    let object = object::File::parse(contents.as_slice()).unwrap();
+    let found = object.exports().unwrap().iter().any(|x| x.name() == name);
+    assert!(found);
 }

tests/ui/linking/export-executable-symbols.rs

@@ -1,22 +1,21 @@
 //@ run-pass
-//@ only-linux
-//@ only-gnu
-//@ compile-flags: -Zexport-executable-symbols
+//@ compile-flags: -Ctarget-feature=-crt-static -Zexport-executable-symbols
+//@ ignore-wasm
 //@ edition: 2024
 
 // Regression test for <https://github.com/rust-lang/rust/issues/101610>.
 
 #![feature(rustc_private)]
 
-extern crate libc;
-
 #[unsafe(no_mangle)]
 fn hack() -> u64 {
     998244353
 }
 
 fn main() {
+    #[cfg(unix)]
     unsafe {
+        extern crate libc;
         let handle = libc::dlopen(std::ptr::null(), libc::RTLD_NOW);
         let ptr = libc::dlsym(handle, c"hack".as_ptr());
         let ptr: Option<unsafe fn() -> u64> = std::mem::transmute(ptr);
@@ -27,4 +26,24 @@ fn main() {
             panic!("symbol `hack` is not found");
         }
     }
+    #[cfg(windows)]
+    unsafe {
+        type PCSTR = *const u8;
+        type HMODULE = *mut core::ffi::c_void;
+        type FARPROC = Option<unsafe extern "system" fn() -> isize>;
+        #[link(name = "kernel32", kind = "raw-dylib")]
+        unsafe extern "system" {
+            fn GetModuleHandleA(lpmodulename: PCSTR) -> HMODULE;
+            fn GetProcAddress(hmodule: HMODULE, lpprocname: PCSTR) -> FARPROC;
+        }
+        let handle = GetModuleHandleA(std::ptr::null_mut());
+        let ptr = GetProcAddress(handle, b"hack\0".as_ptr());
+        let ptr: Option<unsafe fn() -> u64> = std::mem::transmute(ptr);
+        if let Some(f) = ptr {
+            assert!(f() == 998244353);
+            println!("symbol `hack` is found successfully");
+        } else {
+            panic!("symbol `hack` is not found");
+        }
+    }
 }