rustc: Stabilize #[wasm_import_module] as #[link(...)]

src/librustc/hir/check_attr.rs

@@ -65,35 +65,14 @@ impl<'a, 'tcx> CheckAttrVisitor<'a, 'tcx> {
                 .emit();
         }
 
-        let mut has_wasm_import_module = false;
         for attr in &item.attrs {
             if attr.check_name("inline") {
                 self.check_inline(attr, &item.span, target)
             } else if attr.check_name("non_exhaustive") {
                 self.check_non_exhaustive(attr, item, target)
-            } else if attr.check_name("wasm_import_module") {
-                has_wasm_import_module = true;
-                if attr.value_str().is_none() {
-                    self.tcx.sess.span_err(attr.span, "\
-                        must be of the form #[wasm_import_module = \"...\"]");
-                }
-                if target != Target::ForeignMod {
-                    self.tcx.sess.span_err(attr.span, "\
-                        must only be attached to foreign modules");
-                }
             }
         }
 
-        if target == Target::ForeignMod &&
-            !has_wasm_import_module &&
-            self.tcx.sess.target.target.arch == "wasm32" &&
-            false // FIXME: eventually enable this warning when stable
-        {
-            self.tcx.sess.span_warn(item.span, "\
-                must have a #[wasm_import_module = \"...\"] attribute, this \
-                will become a hard error before too long");
-        }
-
         self.check_repr(item, target);
         self.check_used(item, target);
     }

src/librustc/ich/impls_cstore.rs

@@ -31,7 +31,8 @@ impl_stable_hash_for!(struct middle::cstore::NativeLibrary {
     kind,
     name,
     cfg,
-    foreign_module
+    foreign_module,
+    wasm_import_module
 });
 
 impl_stable_hash_for!(struct middle::cstore::ForeignModule {

src/librustc/middle/cstore.rs

@@ -128,9 +128,10 @@ pub enum NativeLibraryKind {
 #[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct NativeLibrary {
     pub kind: NativeLibraryKind,
-    pub name: Symbol,
+    pub name: Option<Symbol>,
     pub cfg: Option<ast::MetaItem>,
     pub foreign_module: Option<DefId>,
+    pub wasm_import_module: Option<Symbol>,
 }
 
 #[derive(Clone, Hash, RustcEncodable, RustcDecodable)]

src/librustc_codegen_llvm/attributes.rs

@@ -226,13 +226,22 @@ pub fn provide(providers: &mut Providers) {
 
 pub fn provide_extern(providers: &mut Providers) {
     providers.wasm_import_module_map = |tcx, cnum| {
+        // Build up a map from DefId to a `NativeLibrary` structure, where
+        // `NativeLibrary` internally contains information about
+        // `#[link(wasm_import_module = "...")]` for example.
+        let native_libs = tcx.native_libraries(cnum);
+        let mut def_id_to_native_lib = FxHashMap();
+        for lib in native_libs.iter() {
+            if let Some(id) = lib.foreign_module {
+                def_id_to_native_lib.insert(id, lib);
+            }
+        }
+
         let mut ret = FxHashMap();
         for lib in tcx.foreign_modules(cnum).iter() {
-            let attrs = tcx.get_attrs(lib.def_id);
-            let mut module = None;
-            for attr in attrs.iter().filter(|a| a.check_name("wasm_import_module")) {
-                module = attr.value_str();
-            }
+            let module = def_id_to_native_lib
+                .get(&lib.def_id)
+                .and_then(|s| s.wasm_import_module);
             let module = match module {
                 Some(s) => s,
                 None => continue,
@@ -244,7 +253,7 @@ pub fn provide_extern(providers: &mut Providers) {
         }
 
         Lrc::new(ret)
-    }
+    };
 }
 
 fn wasm_import_module(tcx: TyCtxt, id: DefId) -> Option<CString> {

src/librustc_codegen_llvm/back/link.rs

@@ -449,7 +449,9 @@ fn link_rlib<'a>(sess: &'a Session,
             NativeLibraryKind::NativeFramework |
             NativeLibraryKind::NativeUnknown => continue,
         }
-        ab.add_native_library(&lib.name.as_str());
+        if let Some(name) = lib.name {
+            ab.add_native_library(&name.as_str());
+        }
     }
 
     // After adding all files to the archive, we need to update the
@@ -583,21 +585,24 @@ fn link_staticlib(sess: &Session,
 fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLibrary]) {
     let lib_args: Vec<_> = all_native_libs.iter()
         .filter(|l| relevant_lib(sess, l))
-        .filter_map(|lib| match lib.kind {
-            NativeLibraryKind::NativeStaticNobundle |
-            NativeLibraryKind::NativeUnknown => {
-                if sess.target.target.options.is_like_msvc {
-                    Some(format!("{}.lib", lib.name))
-                } else {
-                    Some(format!("-l{}", lib.name))
-                }
-            },
-            NativeLibraryKind::NativeFramework => {
-                // ld-only syntax, since there are no frameworks in MSVC
-                Some(format!("-framework {}", lib.name))
-            },
-            // These are included, no need to print them
-            NativeLibraryKind::NativeStatic => None,
+        .filter_map(|lib| {
+            let name = lib.name?;
+            match lib.kind {
+                NativeLibraryKind::NativeStaticNobundle |
+                NativeLibraryKind::NativeUnknown => {
+                    if sess.target.target.options.is_like_msvc {
+                        Some(format!("{}.lib", name))
+                    } else {
+                        Some(format!("-l{}", name))
+                    }
+                },
+                NativeLibraryKind::NativeFramework => {
+                    // ld-only syntax, since there are no frameworks in MSVC
+                    Some(format!("-framework {}", name))
+                },
+                // These are included, no need to print them
+                NativeLibraryKind::NativeStatic => None,
+            }
         })
         .collect();
     if !lib_args.is_empty() {
@@ -1211,11 +1216,15 @@ fn add_local_native_libraries(cmd: &mut dyn Linker,
 
     let search_path = archive_search_paths(sess);
     for lib in relevant_libs {
+        let name = match lib.name {
+            Some(ref l) => l,
+            None => continue,
+        };
         match lib.kind {
-            NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
-            NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
-            NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
-            NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
+            NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
+            NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
+            NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&name.as_str()),
+            NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&name.as_str(),
                                                                         &search_path)
         }
     }
@@ -1578,19 +1587,23 @@ fn add_upstream_native_libraries(cmd: &mut dyn Linker,
     let crates = &codegen_results.crate_info.used_crates_static;
     for &(cnum, _) in crates {
         for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
+            let name = match lib.name {
+                Some(ref l) => l,
+                None => continue,
+            };
             if !relevant_lib(sess, &lib) {
                 continue
             }
             match lib.kind {
-                NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
-                NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
+                NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
+                NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
                 NativeLibraryKind::NativeStaticNobundle => {
                     // Link "static-nobundle" native libs only if the crate they originate from
                     // is being linked statically to the current crate.  If it's linked dynamically
                     // or is an rlib already included via some other dylib crate, the symbols from
                     // native libs will have already been included in that dylib.
                     if data[cnum.as_usize() - 1] == Linkage::Static {
-                        cmd.link_staticlib(&lib.name.as_str())
+                        cmd.link_staticlib(&name.as_str())
                     }
                 },
                 // ignore statically included native libraries here as we've

src/librustc_codegen_llvm/back/wasm.rs

@@ -34,9 +34,9 @@ const WASM_EXTERNAL_KIND_GLOBAL: u8 = 3;
 ///
 /// This function is intended as a hack for now where we manually rewrite the
 /// wasm output by LLVM to have the correct import modules listed. The
-/// `#[wasm_import_module]` attribute in Rust translates to the module that each
-/// symbol is imported from, so here we manually go through the wasm file,
-/// decode it, rewrite imports, and then rewrite the wasm module.
+/// `#[link(wasm_import_module = "...")]` attribute in Rust translates to the
+/// module that each symbol is imported from, so here we manually go through the
+/// wasm file, decode it, rewrite imports, and then rewrite the wasm module.
 ///
 /// Support for this was added to LLVM in
 /// https://github.com/llvm-mirror/llvm/commit/0f32e1365, although support still

src/librustc_metadata/native_libs.rs

@@ -61,56 +61,75 @@ impl<'a, 'tcx> ItemLikeVisitor<'tcx> for Collector<'a, 'tcx> {
                 Some(item) => item,
                 None => continue,
             };
-            let kind = items.iter().find(|k| {
-                k.check_name("kind")
-            }).and_then(|a| a.value_str()).map(Symbol::as_str);
-            let kind = match kind.as_ref().map(|s| &s[..]) {
-                Some("static") => cstore::NativeStatic,
-                Some("static-nobundle") => cstore::NativeStaticNobundle,
-                Some("dylib") => cstore::NativeUnknown,
-                Some("framework") => cstore::NativeFramework,
-                Some(k) => {
-                    struct_span_err!(self.tcx.sess, m.span, E0458,
-                              "unknown kind: `{}`", k)
-                        .span_label(m.span, "unknown kind").emit();
-                    cstore::NativeUnknown
-                }
-                None => cstore::NativeUnknown
-            };
-            let n = items.iter().find(|n| {
-                n.check_name("name")
-            }).and_then(|a| a.value_str());
-            let n = match n {
-                Some(n) => n,
-                None => {
-                    struct_span_err!(self.tcx.sess, m.span, E0459,
-                                     "#[link(...)] specified without `name = \"foo\"`")
-                        .span_label(m.span, "missing `name` argument").emit();
-                    Symbol::intern("foo")
-                }
+            let mut lib = NativeLibrary {
+                name: None,
+                kind: cstore::NativeUnknown,
+                cfg: None,
+                foreign_module: Some(self.tcx.hir.local_def_id(it.id)),
+                wasm_import_module: None,
             };
-            let cfg = items.iter().find(|k| {
-                k.check_name("cfg")
-            }).and_then(|a| a.meta_item_list());
-            let cfg = if let Some(list) = cfg {
-                if list.is_empty() {
-                    self.tcx.sess.span_err(m.span(), "`cfg()` must have an argument");
-                    return;
-                } else if let cfg @ Some(..) = list[0].meta_item() {
-                    cfg.cloned()
+            let mut kind_specified = false;
+
+            for item in items.iter() {
+                if item.check_name("kind") {
+                    kind_specified = true;
+                    let kind = match item.value_str() {
+                        Some(name) => name,
+                        None => continue, // skip like historical compilers
+                    };
+                    lib.kind = match &kind.as_str()[..] {
+                        "static" => cstore::NativeStatic,
+                        "static-nobundle" => cstore::NativeStaticNobundle,
+                        "dylib" => cstore::NativeUnknown,
+                        "framework" => cstore::NativeFramework,
+                        k => {
+                            struct_span_err!(self.tcx.sess, m.span, E0458,
+                                      "unknown kind: `{}`", k)
+                                .span_label(item.span, "unknown kind").emit();
+                            cstore::NativeUnknown
+                        }
+                    };
+                } else if item.check_name("name") {
+                    lib.name = item.value_str();
+                } else if item.check_name("cfg") {
+                    let cfg = match item.meta_item_list() {
+                        Some(list) => list,
+                        None => continue, // skip like historical compilers
+                    };
+                    if cfg.is_empty() {
+                        self.tcx.sess.span_err(
+                            item.span(),
+                            "`cfg()` must have an argument",
+                        );
+                    } else if let cfg @ Some(..) = cfg[0].meta_item() {
+                        lib.cfg = cfg.cloned();
+                    } else {
+                        self.tcx.sess.span_err(cfg[0].span(), "invalid argument for `cfg(..)`");
+                    }
+                } else if item.check_name("wasm_import_module") {
+                    match item.value_str() {
+                        Some(s) => lib.wasm_import_module = Some(s),
+                        None => {
+                            let msg = "must be of the form #[link(wasm_import_module = \"...\")]";
+                            self.tcx.sess.span_err(item.span(), msg);
+                        }
+                    }
                 } else {
-                    self.tcx.sess.span_err(list[0].span(), "invalid argument for `cfg(..)`");
-                    return;
+                    // currently, like past compilers, ignore unknown
+                    // directives here.
                 }
-            } else {
-                None
-            };
-            let lib = NativeLibrary {
-                name: n,
-                kind,
-                cfg,
-                foreign_module: Some(self.tcx.hir.local_def_id(it.id)),
-            };
+            }
+
+            // In general we require #[link(name = "...")] but we allow
+            // #[link(wasm_import_module = "...")] without the `name`.
+            let requires_name = kind_specified || lib.wasm_import_module.is_none();
+            if lib.name.is_none() && requires_name {
+                struct_span_err!(self.tcx.sess, m.span, E0459,
+                                 "#[link(...)] specified without \
+                                  `name = \"foo\"`")
+                    .span_label(m.span, "missing `name` argument")
+                    .emit();
+            }
             self.register_native_lib(Some(m.span), lib);
         }
     }
@@ -121,7 +140,7 @@ impl<'a, 'tcx> ItemLikeVisitor<'tcx> for Collector<'a, 'tcx> {
 
 impl<'a, 'tcx> Collector<'a, 'tcx> {
     fn register_native_lib(&mut self, span: Option<Span>, lib: NativeLibrary) {
-        if lib.name.as_str().is_empty() {
+        if lib.name.as_ref().map(|s| s.as_str().is_empty()).unwrap_or(false) {
             match span {
                 Some(span) => {
                     struct_span_err!(self.tcx.sess, span, E0454,
@@ -167,10 +186,14 @@ impl<'a, 'tcx> Collector<'a, 'tcx> {
         let mut renames = FxHashSet();
         for &(ref name, ref new_name, _) in &self.tcx.sess.opts.libs {
             if let &Some(ref new_name) = new_name {
+                let any_duplicate = self.libs
+                    .iter()
+                    .filter_map(|lib| lib.name.as_ref())
+                    .any(|n| n == name);
                 if new_name.is_empty() {
                     self.tcx.sess.err(
                         &format!("an empty renaming target was specified for library `{}`",name));
-                } else if !self.libs.iter().any(|lib| lib.name == name as &str) {
+                } else if !any_duplicate {
                     self.tcx.sess.err(&format!("renaming of the library `{}` was specified, \
                                                 however this crate contains no #[link(...)] \
                                                 attributes referencing this library.", name));
@@ -189,14 +212,18 @@ impl<'a, 'tcx> Collector<'a, 'tcx> {
         for &(ref name, ref new_name, kind) in &self.tcx.sess.opts.libs {
             let mut found = false;
             for lib in self.libs.iter_mut() {
-                if lib.name == name as &str {
+                let lib_name = match lib.name {
+                    Some(n) => n,
+                    None => continue,
+                };
+                if lib_name == name as &str {
                     let mut changed = false;
                     if let Some(k) = kind {
                         lib.kind = k;
                         changed = true;
                     }
                     if let &Some(ref new_name) = new_name {
-                        lib.name = Symbol::intern(new_name);
+                        lib.name = Some(Symbol::intern(new_name));
                         changed = true;
                     }
                     if !changed {
@@ -212,10 +239,11 @@ impl<'a, 'tcx> Collector<'a, 'tcx> {
                 // Add if not found
                 let new_name = new_name.as_ref().map(|s| &**s); // &Option<String> -> Option<&str>
                 let lib = NativeLibrary {
-                    name: Symbol::intern(new_name.unwrap_or(name)),
+                    name: Some(Symbol::intern(new_name.unwrap_or(name))),
                     kind: if let Some(k) = kind { k } else { cstore::NativeUnknown },
                     cfg: None,
                     foreign_module: None,
+                    wasm_import_module: None,
                 };
                 self.register_native_lib(None, lib);
             }