Statically link proc_macro into proc macros.

src/libproc_macro/Cargo.toml

@@ -5,5 +5,3 @@ version = "0.0.0"
 
 [lib]
 path = "lib.rs"
-crate-type = ["dylib"]
-

src/librustc/middle/dependency_format.rs

@@ -127,9 +127,8 @@ fn calculate_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             sess.crt_static() => Linkage::Static,
         config::CrateType::Executable => Linkage::Dynamic,
 
-        // proc-macro crates are required to be dylibs, and they're currently
-        // required to link to libsyntax as well.
-        config::CrateType::ProcMacro => Linkage::Dynamic,
+        // proc-macro crates are mostly cdylibs, but we also need metadata.
+        config::CrateType::ProcMacro => Linkage::Static,
 
         // No linkage happens with rlibs, we just needed the metadata (which we
         // got long ago), so don't bother with anything.

src/librustc_cratesio_shim/src/lib.rs

@@ -15,4 +15,5 @@
 
 extern crate bitflags;
 extern crate log;
+extern crate proc_macro;
 extern crate unicode_width;