Don't export non-function symbols with emscripten

Emscripten only provides an export mechanism for functions.
Exporting statics does not make sense conceptually in this case,
and will result in emcc undefined function errors.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/librustc_codegen_utils/symbol_export.rs b/src/librustc_codegen_utils/symbol_export.rs
index 2d650f7f18d..6c40296b2ef 100644
--- a/src/librustc_codegen_utils/symbol_export.rs
+++ b/src/librustc_codegen_utils/symbol_export.rs
@@ -388,6 +388,16 @@ fn symbol_export_level(tcx: TyCtxt, sym_def_id: DefId) -> SymbolExportLevel {
         codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL);
 
     if is_extern && !std_internal {
+        // Emscripten cannot export statics, so reduce their export level here
+        if tcx.sess.target.target.options.is_like_emscripten {
+            if let Some(Node::Item(&hir::Item {
+                node: hir::ItemKind::Static(..),
+                ..
+            })) = tcx.hir.get_if_local(sym_def_id) {
+                return SymbolExportLevel::Rust;
+            }
+        }
+
         SymbolExportLevel::C
     } else {
         SymbolExportLevel::Rust