implement link-arg as an attribute

Author: zetanumbers

compiler/rustc_feature/src/unstable.rs

@@ -500,6 +500,9 @@ declare_features! (
     (incomplete, lazy_type_alias, "1.72.0", Some(112792), None),
     /// Allows `if/while p && let q = r && ...` chains.
     (unstable, let_chains, "1.37.0", Some(53667), None),
+    /// Allows using `#[link(kind = "link-arg", name = "...")]`
+    /// to pass custom arguments to the linker.
+    (unstable, link_arg_attribute, "CURRENT_RUSTC_VERSION", Some(99427), None),
     /// Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check.
     (unstable, lint_reasons, "1.31.0", Some(54503), None),
     /// Give access to additional metadata about declarative macro meta-variables.

compiler/rustc_metadata/messages.ftl

@@ -269,7 +269,7 @@ metadata_unknown_import_name_type =
     unknown import name type `{$import_name_type}`, expected one of: decorated, noprefix, undecorated
 
 metadata_unknown_link_kind =
-    unknown link kind `{$kind}`, expected one of: static, dylib, framework, raw-dylib
+    unknown link kind `{$kind}`, expected one of: static, dylib, framework, raw-dylib, link-arg
     .label = unknown link kind
 
 metadata_unknown_link_modifier =

compiler/rustc_metadata/src/native_libs.rs

@@ -160,6 +160,18 @@ impl<'tcx> Collector<'tcx> {
                                 }
                                 NativeLibKind::RawDylib
                             }
+                            "link-arg" => {
+                                if !features.link_arg_attribute {
+                                    feature_err(
+                                        &sess.parse_sess,
+                                        sym::link_arg_attribute,
+                                        item.span(),
+                                        "link-arg link kind is unstable",
+                                    )
+                                    .emit();
+                                }
+                                NativeLibKind::LinkArg
+                            }
                             kind => {
                                 sess.emit_err(errors::UnknownLinkKind { span, kind });
                                 continue;

compiler/rustc_span/src/symbol.rs

@@ -950,6 +950,7 @@ symbols! {
         likely,
         line,
         link,
+        link_arg_attribute,
         link_args,
         link_cfg,
         link_llvm_intrinsics,

tests/run-make/linker-flags-from-attribute-flavor/Makefile

@@ -0,0 +1,8 @@
+# only-linux
+
+include ../tools.mk
+
+all:
+	$(RUSTC) no_verbatim.rs -Z unstable-options -C linker-flavor=gnu-cc --print link-args | $(CGREP) -e 'l1.*-Wl,a1.*l2.*-Wl,a2.*d1.*-Wl,a3'
+	$(RUSTC) verbatim.rs -Z unstable-options -C linker-flavor=gnu-cc --print link-args | $(CGREP) -e 'l1.*"a1".*l2.*-Wl,a2.*d1.*-Wl,a3'
+	$(RUSTC) no_verbatim.rs -C linker-flavor=ld --print link-args | $(CGREP) -e 'l1.*"a1".*l2.*"a2".*d1.*"a3"'

tests/run-make/linker-flags-from-attribute-flavor/no_verbatim.rs

@@ -0,0 +1,11 @@
+#![feature(link_arg_attribute)]
+
+#[link(kind = "static", name = "l1")]
+#[link(kind = "link-arg", name = "a1")]
+#[link(kind = "static", name = "l2")]
+#[link(kind = "link-arg", name = "a2")]
+#[link(kind = "dylib", name = "d1")]
+#[link(kind = "link-arg", name = "a3")]
+extern "C" {}
+
+fn main() {}

tests/run-make/linker-flags-from-attribute-flavor/verbatim.rs

@@ -0,0 +1,11 @@
+#![feature(link_arg_attribute)]
+
+#[link(kind = "static", name = "l1")]
+#[link(kind = "link-arg", name = "a1", modifiers = "+verbatim")]
+#[link(kind = "static", name = "l2")]
+#[link(kind = "link-arg", name = "a2")]
+#[link(kind = "dylib", name = "d1")]
+#[link(kind = "link-arg", name = "a3")]
+extern "C" {}
+
+fn main() {}

tests/run-make/linker-flags-from-attribute-from-dep/Makefile

@@ -0,0 +1,10 @@
+include ../tools.mk
+
+all:
+	# Build deps
+	$(RUSTC) native_dep_1.rs --crate-type=staticlib
+	$(RUSTC) native_dep_2.rs --crate-type=staticlib
+	$(RUSTC) rust_dep.rs --crate-type=lib
+
+	# Check sequence of linker args
+	$(RUSTC) main.rs --extern lib=$(TMPDIR)/librust_dep.rlib --crate-type=bin --print link-args | $(CGREP) -e 'native_dep_1.*some_flag.*native_dep_2'

tests/run-make/linker-flags-from-attribute-from-dep/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    lib::f();
+}

tests/run-make/linker-flags-from-attribute-from-dep/native_dep_1.rs

@@ -0,0 +1 @@
+pub fn f1() {}