Commit 58618afaee

Luuk de Gram <luuk@degram.dev>
2023-08-31 17:12:12
wasm-linker: correctly pass --shared and --pie
When linking a WebAssembly binary using wasm-ld, we will now correctly pass --shared when building a dynamic library and --pie when `-fpic` is given. This is a breaking change and users who currently build dynamic libraries for WebAssembly but wish to have an executable without a main, should use build-exe instead while supplying `-fno-entry`. We also verify the user does not supply --export-memory when -dynamic is enabled. By default we set this flag now to 'false' when `-dynamic` is used to ensure we do not enable it as it's enabled by default for regular WebAssembly binaries.
master
1 parent 1cb7a01
Changed files (2)
src
link
Wasm.zig
main.zig
src/link/Wasm.zig
@@ -4548,6 +4548,13 @@ fn linkWithLLD(wasm: *Wasm, comp: *Compilation, prog_node: *std.Progress.Node) !
             try argv.append("--no-entry");
         }
 
+        if (wasm.base.options.output_mode == .Lib and wasm.base.options.link_mode == .Dynamic) {
+            try argv.append("--shared");
+        }
+        if (wasm.base.options.pie) {
+            try argv.append("--pie");
+        }
+
         // XXX - TODO: add when wasm-ld supports --build-id.
         // if (wasm.base.options.build_id) {
         //     try argv.append("--build-id=tree");
src/main.zig
@@ -2627,6 +2627,16 @@ fn buildOutputType(
         if (single_threaded == null) {
             single_threaded = true;
         }
+        if (link_mode) |mode| {
+            if (mode == .Dynamic) {
+                if (linker_export_memory != null and linker_export_memory.?) {
+                    fatal("flags '-dynamic' and '--export-memory' are incompatible", .{});
+                }
+                // User did not supply `--export-memory` which is incompatible with -dynamic, therefore
+                // set the flag to false to ensure it does not get enabled by default.
+                linker_export_memory = false;
+            }
+        }
         if (wasi_exec_model) |model| {
             if (model == .reactor) {
                 if (linker_no_entry != null and !linker_no_entry.?) {