rust-lang · usamoi · Aug 26, 2025
diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
@@ -197,7 +197,7 @@ attr_parsing_suffixed_literal_in_attribute = suffixed literals are not allowed i
     .help = instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
 
 attr_parsing_as_needed_compatibility =
-    linking modifier `as-needed` is only compatible with `dylib` and `framework` linking kinds
+    linking modifier `as-needed` is only compatible with `dylib`, `framework` and `raw-dylib` linking kinds
 
 attr_parsing_bundle_needs_static =
     linking modifier `bundle` is only compatible with `static` linking kind

diff --git a/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
@@ -168,7 +168,8 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
                     }
 
                     (sym::as_dash_needed, Some(NativeLibKind::Dylib { as_needed }))
-                    | (sym::as_dash_needed, Some(NativeLibKind::Framework { as_needed })) => {
+                    | (sym::as_dash_needed, Some(NativeLibKind::Framework { as_needed }))
+                    | (sym::as_dash_needed, Some(NativeLibKind::RawDylib { as_needed })) => {
                         report_unstable_modifier!(native_link_modifiers_as_needed);
                         assign_modifier(as_needed)
                     }
@@ -207,12 +208,12 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
 
         // Do this outside of the loop so that `import_name_type` can be specified before `kind`.
         if let Some((_, span)) = import_name_type {
-            if kind != Some(NativeLibKind::RawDylib) {
+            if !matches!(kind, Some(NativeLibKind::RawDylib { .. })) {
                 cx.emit_err(ImportNameTypeRaw { span });
             }
         }
 
-        if let Some(NativeLibKind::RawDylib) = kind
+        if let Some(NativeLibKind::RawDylib { .. }) = kind
             && name.as_str().contains('\0')
         {
             cx.emit_err(RawDylibNoNul { span: name_span });
@@ -304,7 +305,7 @@ impl LinkParser {
                     cx.emit_err(RawDylibOnlyWindows { span: nv.value_span });
                 }
 
-                NativeLibKind::RawDylib
+                NativeLibKind::RawDylib { as_needed: None }
             }
             sym::link_dash_arg => {
                 if !features.link_arg_attribute() {

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1485,7 +1485,7 @@ fn print_native_static_libs(
                 NativeLibKind::Static { bundle: None | Some(true), .. }
                 | NativeLibKind::LinkArg
                 | NativeLibKind::WasmImportModule
-                | NativeLibKind::RawDylib => None,
+                | NativeLibKind::RawDylib { .. } => None,
             }
         })
         // deduplication of consecutive repeated libraries, see rust-lang/rust#113209
@@ -2349,13 +2349,13 @@ fn linker_with_args(
             cmd.add_object(&output_path);
         }
     } else {
-        for link_path in raw_dylib::create_raw_dylib_elf_stub_shared_objects(
+        for (link_path, as_needed) in raw_dylib::create_raw_dylib_elf_stub_shared_objects(
             sess,
             codegen_results.crate_info.used_libraries.iter(),
             &raw_dylib_dir,
         ) {
             // Always use verbatim linkage, see comments in create_raw_dylib_elf_stub_shared_objects.
-            cmd.link_dylib_by_name(&link_path, true, false);
+            cmd.link_dylib_by_name(&link_path, true, as_needed);
         }
     }
     // As with add_upstream_native_libraries, we need to add the upstream raw-dylib symbols in case
@@ -2396,13 +2396,13 @@ fn linker_with_args(
             cmd.add_object(&output_path);
         }
     } else {
-        for link_path in raw_dylib::create_raw_dylib_elf_stub_shared_objects(
+        for (link_path, as_needed) in raw_dylib::create_raw_dylib_elf_stub_shared_objects(
             sess,
             native_libraries_from_nonstatics,
             &raw_dylib_dir,
         ) {
             // Always use verbatim linkage, see comments in create_raw_dylib_elf_stub_shared_objects.
-            cmd.link_dylib_by_name(&link_path, true, false);
+            cmd.link_dylib_by_name(&link_path, true, as_needed);
         }
     }
 
@@ -2711,7 +2711,7 @@ fn add_native_libs_from_crate(
                     cmd.link_framework_by_name(name, verbatim, as_needed.unwrap_or(true))
                 }
             }
-            NativeLibKind::RawDylib => {
+            NativeLibKind::RawDylib { as_needed: _ } => {
                 // Handled separately in `linker_with_args`.
             }
             NativeLibKind::WasmImportModule => {}

diff --git a/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs b/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs
@@ -31,7 +31,7 @@ fn collate_raw_dylibs_windows<'a>(
     let mut dylib_table = FxIndexMap::<String, FxIndexMap<Symbol, &DllImport>>::default();
 
     for lib in used_libraries {
-        if lib.kind == NativeLibKind::RawDylib {
+        if let NativeLibKind::RawDylib { .. } = lib.kind {
             let ext = if lib.verbatim { "" } else { ".dll" };
             let name = format!("{}{}", lib.name, ext);
             let imports = dylib_table.entry(name.clone()).or_default();
@@ -128,12 +128,12 @@ pub(super) fn create_raw_dylib_dll_import_libs<'a>(
 fn collate_raw_dylibs_elf<'a>(
     sess: &Session,
     used_libraries: impl IntoIterator<Item = &'a NativeLib>,
-) -> Vec<(String, Vec<DllImport>)> {
+) -> Vec<(String, Vec<DllImport>, bool)> {
     // Use index maps to preserve original order of imports and libraries.
-    let mut dylib_table = FxIndexMap::<String, FxIndexMap<Symbol, &DllImport>>::default();
+    let mut dylib_table = FxIndexMap::<String, (FxIndexMap<Symbol, &DllImport>, bool)>::default();
 
     for lib in used_libraries {
-        if lib.kind == NativeLibKind::RawDylib {
+        if let NativeLibKind::RawDylib { as_needed } = lib.kind {
             let filename = if lib.verbatim {
                 lib.name.as_str().to_owned()
             } else {
@@ -142,17 +142,19 @@ fn collate_raw_dylibs_elf<'a>(
                 format!("{prefix}{}{ext}", lib.name)
             };
 
-            let imports = dylib_table.entry(filename.clone()).or_default();
+            let (stub_imports, stub_as_needed) =
+                dylib_table.entry(filename.clone()).or_insert((Default::default(), true));
             for import in &lib.dll_imports {
-                imports.insert(import.name, import);
+                stub_imports.insert(import.name, import);
             }
+            *stub_as_needed = *stub_as_needed && as_needed.unwrap_or(true);
         }
     }
     sess.dcx().abort_if_errors();
     dylib_table
         .into_iter()
-        .map(|(name, imports)| {
-            (name, imports.into_iter().map(|(_, import)| import.clone()).collect())
+        .map(|(name, (imports, as_needed))| {
+            (name, imports.into_iter().map(|(_, import)| import.clone()).collect(), as_needed)
         })
         .collect()
 }
@@ -161,10 +163,10 @@ pub(super) fn create_raw_dylib_elf_stub_shared_objects<'a>(
     sess: &Session,
     used_libraries: impl IntoIterator<Item = &'a NativeLib>,
     raw_dylib_so_dir: &Path,
-) -> Vec<String> {
+) -> Vec<(String, bool)> {
     collate_raw_dylibs_elf(sess, used_libraries)
         .into_iter()
-        .map(|(load_filename, raw_dylib_imports)| {
+        .map(|(load_filename, raw_dylib_imports, as_needed)| {
             use std::hash::Hash;
 
             // `load_filename` is the *target/loader* filename that will end up in NEEDED.
@@ -205,7 +207,7 @@ pub(super) fn create_raw_dylib_elf_stub_shared_objects<'a>(
                 });
             };
 
-            temporary_lib_name
+            (temporary_lib_name, as_needed)
         })
         .collect()
 }

diff --git a/compiler/rustc_hir/src/attrs/data_structures.rs b/compiler/rustc_hir/src/attrs/data_structures.rs
@@ -307,7 +307,10 @@ pub enum NativeLibKind {
     },
     /// Dynamic library (e.g. `foo.dll` on Windows) without a corresponding import library.
     /// On Linux, it refers to a generated shared library stub.
-    RawDylib,
+    RawDylib {
+        /// Whether the dynamic library will be linked only if it satisfies some undefined symbols
+        as_needed: Option<bool>,
+    },
     /// A macOS-specific kind of dynamic libraries.
     Framework {
         /// Whether the framework will be linked only if it satisfies some undefined symbols
@@ -330,11 +333,10 @@ impl NativeLibKind {
             NativeLibKind::Static { bundle, whole_archive } => {
                 bundle.is_some() || whole_archive.is_some()
             }
-            NativeLibKind::Dylib { as_needed } | NativeLibKind::Framework { as_needed } => {
-                as_needed.is_some()
-            }
-            NativeLibKind::RawDylib
-            | NativeLibKind::Unspecified
+            NativeLibKind::Dylib { as_needed }
+            | NativeLibKind::Framework { as_needed }
+            | NativeLibKind::RawDylib { as_needed } => as_needed.is_some(),
+            NativeLibKind::Unspecified
             | NativeLibKind::LinkArg
             | NativeLibKind::WasmImportModule => false,
         }
@@ -347,7 +349,9 @@ impl NativeLibKind {
     pub fn is_dllimport(&self) -> bool {
         matches!(
             self,
-            NativeLibKind::Dylib { .. } | NativeLibKind::RawDylib | NativeLibKind::Unspecified
+            NativeLibKind::Dylib { .. }
+                | NativeLibKind::RawDylib { .. }
+                | NativeLibKind::Unspecified
         )
     }
 }

diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
@@ -218,7 +218,7 @@ impl<'tcx> Collector<'tcx> {
                 .flatten()
         {
             let dll_imports = match attr.kind {
-                NativeLibKind::RawDylib => foreign_items
+                NativeLibKind::RawDylib { .. } => foreign_items
                     .iter()
                     .map(|&child_item| {
                         self.build_dll_import(

diff --git a/compiler/rustc_session/src/config/native_libs.rs b/compiler/rustc_session/src/config/native_libs.rs
@@ -135,7 +135,8 @@ fn parse_and_apply_modifier(cx: &ParseNativeLibCx<'_>, modifier: &str, native_li
         ),
 
         ("as-needed", NativeLibKind::Dylib { as_needed })
-        | ("as-needed", NativeLibKind::Framework { as_needed }) => {
+        | ("as-needed", NativeLibKind::Framework { as_needed })
+        | ("as-needed", NativeLibKind::RawDylib { as_needed }) => {
             cx.on_unstable_value(
                 "linking modifier `as-needed` is unstable",
                 ", the `-Z unstable-options` flag must also be passed to use it",

diff --git a/tests/ui/linkage-attr/raw-dylib/elf/as_needed.rs b/tests/ui/linkage-attr/raw-dylib/elf/as_needed.rs
@@ -0,0 +1,43 @@
+//@ only-elf
+//@ needs-dynamic-linking
+
+//@ only-gnu
+//@ only-x86_64
+//@ revisions: as_needed no_as_needed no_modifier merge_1 merge_2 merge_3 merge_4
+
+//@ [as_needed] run-pass
+//@ [no_as_needed] run-fail
+//@ [no_modifier] run-pass
+//@ [merge_1] run-fail
+//@ [merge_2] run-fail
+//@ [merge_3] run-fail
+//@ [merge_4] run-pass
+
+#![allow(incomplete_features)]
+#![feature(raw_dylib_elf)]
+#![feature(native_link_modifiers_as_needed)]
+
+#[cfg_attr(
+    as_needed,
+    link(name = "taiqannf1y28z2rw", kind = "raw-dylib", modifiers = "+as-needed")
+)]
+#[cfg_attr(
+    no_as_needed,
+    link(name = "taiqannf1y28z2rw", kind = "raw-dylib", modifiers = "-as-needed")
+)]
+#[cfg_attr(no_modifier, link(name = "taiqannf1y28z2rw", kind = "raw-dylib"))]
+unsafe extern "C" {}
+
+#[cfg_attr(merge_1, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "+as-needed"))]
+#[cfg_attr(merge_2, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "-as-needed"))]
+#[cfg_attr(merge_3, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "-as-needed"))]
+#[cfg_attr(merge_4, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "+as-needed"))]
+unsafe extern "C" {}
+
+#[cfg_attr(merge_1, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "-as-needed"))]
+#[cfg_attr(merge_2, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "+as-needed"))]
+#[cfg_attr(merge_3, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "-as-needed"))]
+#[cfg_attr(merge_4, link(name = "k9nm7qxoa79bg7e6", kind = "raw-dylib", modifiers = "+as-needed"))]
+unsafe extern "C" {}
+
+fn main() {}