Skip to content

Commit

Permalink
Implement -Zlink-native-libraries
Browse files Browse the repository at this point in the history
This implements a flag `-Zlink-native-libraries=yes/no`. If set to true/yes, or unspecified, then
native libraries referenced via `#[link]` attributes will be put on the linker line (ie, unchanged
behaviour).

If `-Zlink-native-libraries=no` is specified then rustc will not add the native libraries to the link
line. The assumption is that the outer build system driving the build already knows about the native
libraries and will specify them to the linker directly (for example via `-Clink-arg=`).

Addresses issue rust-lang#70093
  • Loading branch information
jsgf committed Mar 27, 2020
1 parent 0a2df62 commit 53c4e0c
Show file tree
Hide file tree
Showing 3 changed files with 20 additions and 3 deletions.
13 changes: 10 additions & 3 deletions src/librustc_codegen_ssa/back/link.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1379,10 +1379,17 @@ fn link_args<'a, B: ArchiveBuilder<'a>>(
// link line. And finally upstream native libraries can't depend on anything
// in this DAG so far because they're only dylibs and dylibs can only depend
// on other dylibs (e.g., other native deps).
add_local_native_libraries(cmd, sess, codegen_results);
//
// If -Zlink-native-libraries=false is set, then the assumption is that an
// external build system already has the native dependencies defined, and it
// will provide them to the linker itself.
if sess.opts.debugging_opts.link_native_libraries.unwrap_or(true) {
add_local_native_libraries(cmd, sess, codegen_results);
}
add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);

if sess.opts.debugging_opts.link_native_libraries.unwrap_or(true) {
add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
}
// Tell the linker what we're doing.
if crate_type != config::CrateType::Executable {
cmd.build_dylib(out_filename);
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_session/options.rs
Original file line number Diff line number Diff line change
Expand Up @@ -959,4 +959,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
"link the `.rlink` file generated by `-Z no-link`"),
new_llvm_pass_manager: Option<bool> = (None, parse_opt_bool, [TRACKED],
"use new LLVM pass manager"),
link_native_libraries: Option<bool> = (None, parse_opt_bool, [UNTRACKED],
"Link native libraries in the linker invocation."),
}
8 changes: 8 additions & 0 deletions src/test/ui/issues/issue-70093.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
// run-pass
// compile-flags: -Zlink-native-libraries=no -Cdefault-linker-libraries=yes
// ignore-windows - this will probably only work on unixish systems

#[link(name = "some-random-non-existent-library", kind = "static")]
extern "C" {}

fn main() {}

0 comments on commit 53c4e0c

Please sign in to comment.