Rollup merge of rust-lang#63948 - crlf0710:path_to_raw_dylib, r=Centril

Add feature gate for raw_dylib.

This PR adds the feature gate for RFC 2627 (rust-lang#58713). It doesn't contain the actual functionality.
Add I'm not sure whether i did it correctly, since this is the first time i did this.

r? @Centril

Author: Centril

src/librustc/hir/mod.rs

@@ -2669,6 +2669,11 @@ pub struct CodegenFnAttrs {
     /// probably isn't set when this is set, this is for foreign items while
     /// `#[export_name]` is for Rust-defined functions.
     pub link_name: Option<Symbol>,
+    /// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an
+    /// imported function has in the dynamic library. Note that this must not
+    /// be set when `link_name` is set. This is for foreign items with the
+    /// "raw-dylib" kind.
+    pub link_ordinal: Option<usize>,
     /// The `#[target_feature(enable = "...")]` attribute and the enabled
     /// features (only enabled features are supported right now).
     pub target_features: Vec<Symbol>,
@@ -2728,6 +2733,7 @@ impl CodegenFnAttrs {
             optimize: OptimizeAttr::None,
             export_name: None,
             link_name: None,
+            link_ordinal: None,
             target_features: vec![],
             linkage: None,
             link_section: None,

src/librustc/middle/cstore.rs

@@ -96,6 +96,8 @@ pub enum NativeLibraryKind {
     NativeStaticNobundle,
     /// macOS-specific
     NativeFramework,
+    /// Windows dynamic library without import library.
+    NativeRawDylib,
     /// default way to specify a dynamic library
     NativeUnknown,
 }

src/librustc_codegen_ssa/back/link.rs

@@ -323,6 +323,7 @@ fn link_rlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
             NativeLibraryKind::NativeStatic => {}
             NativeLibraryKind::NativeStaticNobundle |
             NativeLibraryKind::NativeFramework |
+            NativeLibraryKind::NativeRawDylib |
             NativeLibraryKind::NativeUnknown => continue,
         }
         if let Some(name) = lib.name {
@@ -883,7 +884,8 @@ pub fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLibrary
                     Some(format!("-framework {}", name))
                 },
                 // These are included, no need to print them
-                NativeLibraryKind::NativeStatic => None,
+                NativeLibraryKind::NativeStatic |
+                NativeLibraryKind::NativeRawDylib => None,
             }
         })
         .collect();
@@ -1293,7 +1295,11 @@ pub fn add_local_native_libraries(cmd: &mut dyn Linker,
             NativeLibraryKind::NativeUnknown => cmd.link_dylib(name),
             NativeLibraryKind::NativeFramework => cmd.link_framework(name),
             NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(name),
-            NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(name, &search_path)
+            NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(name, &search_path),
+            NativeLibraryKind::NativeRawDylib => {
+                // FIXME(#58713): Proper handling for raw dylibs.
+                bug!("raw_dylib feature not yet implemented");
+            },
         }
     }
 }
@@ -1678,7 +1684,11 @@ pub fn add_upstream_native_libraries(
                 // ignore statically included native libraries here as we've
                 // already included them when we included the rust library
                 // previously
-                NativeLibraryKind::NativeStatic => {}
+                NativeLibraryKind::NativeStatic => {},
+                NativeLibraryKind::NativeRawDylib => {
+                    // FIXME(#58713): Proper handling for raw dylibs.
+                    bug!("raw_dylib feature not yet implemented");
+                },
             }
         }
     }

src/librustc_metadata/cstore_impl.rs

@@ -270,7 +270,11 @@ pub fn provide(providers: &mut Providers<'_>) {
     // resolve! Does this work? Unsure! That's what the issue is about
     *providers = Providers {
         is_dllimport_foreign_item: |tcx, id| {
-            tcx.native_library_kind(id) == Some(NativeLibraryKind::NativeUnknown)
+            match tcx.native_library_kind(id) {
+                Some(NativeLibraryKind::NativeUnknown) |
+                Some(NativeLibraryKind::NativeRawDylib) => true,
+                _ => false,
+            }
         },
         is_statically_included_foreign_item: |tcx, id| {
             match tcx.native_library_kind(id) {

src/librustc_metadata/native_libs.rs

@@ -73,6 +73,7 @@ impl ItemLikeVisitor<'tcx> for Collector<'tcx> {
                         "static-nobundle" => cstore::NativeStaticNobundle,
                         "dylib" => cstore::NativeUnknown,
                         "framework" => cstore::NativeFramework,
+                        "raw-dylib" => cstore::NativeRawDylib,
                         k => {
                             struct_span_err!(self.tcx.sess, item.span(), E0458,
                                       "unknown kind: `{}`", k)
@@ -169,6 +170,14 @@ impl Collector<'tcx> {
                                            GateIssue::Language,
                                            "kind=\"static-nobundle\" is unstable");
         }
+        if lib.kind == cstore::NativeRawDylib &&
+           !self.tcx.features().raw_dylib {
+            feature_gate::emit_feature_err(&self.tcx.sess.parse_sess,
+                                           sym::raw_dylib,
+                                           span.unwrap_or_else(|| syntax_pos::DUMMY_SP),
+                                           GateIssue::Language,
+                                           "kind=\"raw-dylib\" is unstable");
+        }
         self.libs.push(lib);
     }
 

src/librustc_typeck/collect.rs

@@ -2560,6 +2560,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
     let whitelist = tcx.target_features_whitelist(LOCAL_CRATE);
 
     let mut inline_span = None;
+    let mut link_ordinal_span = None;
     for attr in attrs.iter() {
         if attr.check_name(sym::cold) {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
@@ -2641,6 +2642,11 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
             }
         } else if attr.check_name(sym::link_name) {
             codegen_fn_attrs.link_name = attr.value_str();
+        } else if attr.check_name(sym::link_ordinal) {
+            link_ordinal_span = Some(attr.span);
+            if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
+                codegen_fn_attrs.link_ordinal = ordinal;
+            }
         }
     }
 
@@ -2718,6 +2724,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
     // purpose functions as they wouldn't have the right target features
     // enabled. For that reason we also forbid #[inline(always)] as it can't be
     // respected.
+
     if codegen_fn_attrs.target_features.len() > 0 {
         if codegen_fn_attrs.inline == InlineAttr::Always {
             if let Some(span) = inline_span {
@@ -2742,6 +2749,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
         codegen_fn_attrs.export_name = Some(name);
         codegen_fn_attrs.link_name = Some(name);
     }
+    check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
 
     // Internal symbols to the standard library all have no_mangle semantics in
     // that they have defined symbol names present in the function name. This
@@ -2752,3 +2760,48 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
 
     codegen_fn_attrs
 }
+
+fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<usize> {
+    use syntax::ast::{Lit, LitIntType, LitKind};
+    let meta_item_list = attr.meta_item_list();
+    let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
+    let sole_meta_list = match meta_item_list {
+        Some([item]) => item.literal(),
+        _ => None,
+    };
+    if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
+        if *ordinal <= std::usize::MAX as u128 {
+            Some(*ordinal as usize)
+        } else {
+            let msg = format!(
+                "ordinal value in `link_ordinal` is too large: `{}`",
+                &ordinal
+            );
+            tcx.sess.struct_span_err(attr.span, &msg)
+                .note("the value may not exceed `std::usize::MAX`")
+                .emit();
+            None
+        }
+    } else {
+        tcx.sess.struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
+            .note("an unsuffixed integer value, e.g., `1`, is expected")
+            .emit();
+        None
+    }
+}
+
+fn check_link_name_xor_ordinal(
+    tcx: TyCtxt<'_>,
+    codegen_fn_attrs: &CodegenFnAttrs,
+    inline_span: Option<Span>,
+) {
+    if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
+        return;
+    }
+    let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
+    if let Some(span) = inline_span {
+        tcx.sess.span_err(span, msg);
+    } else {
+        tcx.sess.err(msg);
+    }
+}

src/libsyntax/feature_gate/active.rs

@@ -522,6 +522,9 @@ declare_features! (
     /// Allows the definition of `const extern fn` and `const unsafe extern fn`.
     (active, const_extern_fn, "1.40.0", Some(64926), None),
 
+    // Allows the use of raw-dylibs (RFC 2627).
+    (active, raw_dylib, "1.40.0", Some(58713), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------
@@ -536,4 +539,5 @@ pub const INCOMPLETE_FEATURES: &[Symbol] = &[
     sym::const_generics,
     sym::or_patterns,
     sym::let_chains,
+    sym::raw_dylib,
 ];

src/libsyntax/feature_gate/builtin_attrs.rs

@@ -276,6 +276,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         "the `link_args` attribute is experimental and not portable across platforms, \
         it is recommended to use `#[link(name = \"foo\")] instead",
     ),
+    gated!(
+        link_ordinal, Whitelisted, template!(List: "ordinal"), raw_dylib,
+        experimental!(link_ordinal)
+    ),
 
     // Plugins:
     (

src/libsyntax_pos/symbol.rs

@@ -389,6 +389,7 @@ symbols! {
         link_cfg,
         link_llvm_intrinsics,
         link_name,
+        link_ordinal,
         link_section,
         LintPass,
         lint_reasons,
@@ -531,6 +532,7 @@ symbols! {
         RangeInclusive,
         RangeTo,
         RangeToInclusive,
+        raw_dylib,
         raw_identifiers,
         Ready,
         reason,

src/test/ui/rfc-2627-raw-dylib/feature-gate-raw-dylib-2.rs

@@ -0,0 +1,8 @@
+#[link(name="foo")]
+extern {
+    #[link_ordinal(42)]
+    //~^ ERROR: the `#[link_ordinal]` attribute is an experimental feature
+    fn foo();
+}
+
+fn main() {}