Auto merge of #118417 - anforowicz:default-hidden-visibility, r=TaKO8Ki

Add unstable `-Zdefault-hidden-visibility` cmdline flag for `rustc`.

The new flag has been described in the Major Change Proposal at
https://github.com/rust-lang/compiler-team/issues/656

1 files changed, 31 insertions, 0 deletions

diff --git a/tests/codegen/default-hidden-visibility.rs b/tests/codegen/default-hidden-visibility.rs
new file mode 100644
index 00000000000..9e5e545f0d9
--- /dev/null
+++ b/tests/codegen/default-hidden-visibility.rs
@@ -0,0 +1,31 @@
+// Verifies that `Session::default_hidden_visibility` is affected when using the related cmdline
+// flag.  This is a regression test for https://github.com/rust-lang/compiler-team/issues/656.  See
+// also https://github.com/rust-lang/rust/issues/73295 and
+// https://github.com/rust-lang/rust/issues/37530.
+
+// revisions:DEFAULT YES NO
+//[YES] compile-flags: -Zdefault-hidden-visibility=yes
+//[NO]  compile-flags: -Zdefault-hidden-visibility=no
+
+// The test scenario is specifically about visibility of symbols exported out of dynamically linked
+// libraries.
+#![crate_type = "dylib"]
+
+// The test scenario needs to use a Rust-public, but non-explicitly-exported symbol
+// (e.g. the test doesn't use `#[no_mangle]`, because currently it implies that
+// the symbol should be exported;  we don't want that - we want to test the *default*
+// export setting instead).
+#[used]
+pub static tested_symbol: [u8; 6] = *b"foobar";
+
+// Exact LLVM IR differs depending on the target triple (e.g. `hidden constant`
+// vs `internal constant` vs `constant`).  Because of this, we only apply the
+// specific test expectations below to one specific target triple.  If needed,
+// additional targets can be covered by adding copies of this test file with
+// a different `only-X` directive.
+//
+//     only-x86_64-unknown-linux-gnu
+
+// DEFAULT: @{{.*}}default_hidden_visibility{{.*}}tested_symbol{{.*}} = constant
+// YES:     @{{.*}}default_hidden_visibility{{.*}}tested_symbol{{.*}} = hidden constant
+// NO:      @{{.*}}default_hidden_visibility{{.*}}tested_symbol{{.*}} = constant