[lld][WebAssembly] Trace export of symbols when specified with --trace-symbol. NFC

[dschuff]

Is it possible/useful to also list the name under which the symbol was exported?

[sbc100]

In D148190#4265750, @dschuff wrote:

Is it possible/useful to also list the name under which the symbol was exported?

The indent of the stub object is that it gets exported under it default name (i.e. toString(*needed)). You are correct though that a symbol with custom export name might not work as expected here.

lld/wasm/Driver.cpp

for (auto [name, deps]: stub_file->symbolDependencies) {
         if (!needed) {
           error(toString(stub_file) + ": undefined symbol: " + dep +
                 ". Required by " + toString(*sym));
         } else if (needed->isUndefined()) {
           error(toString(stub_file) +
                 ": undefined symbol: " + toString(*needed) +
                 ". Required by " + toString(*sym));
         } else {
+          if (needed->traced)
+            message(toString(stub_file) + ": exported " + toString(*needed) +
+                    " due to import of " + name);
+          else
             LLVM_DEBUG(llvm::dbgs()
                        << "force export: " << toString(*needed) << "\n");
           needed->forceExport = true;
           if (auto *lazy = dyn_cast<LazySymbol>(needed)) {
             lazy->fetch();
             if (!config->whyExtract.empty())
               config->whyExtractRecords.emplace_back(stub_file->getName(),
                                                      sym->getFile(), *sym);
           }
         }