[WebAssembly] Add assertion for init function signature

[ncw]

Summary

Split out from D43933

[sbc100]

Nice!

Can you update the title? (this is adding validation, not an assertion).

And I don't think you need to mention other change which it used to be part of (at least not in the description that lands in svn).

[ruiu]

wasm/Writer.cpp

899

... init func: " + toString(Sym)

[ncw]

wasm/Writer.cpp

899

Fixed.

wasm/Writer.cpp

 }
 
 // Populate InitFunctions vector with init functions from all input objects.
 // This is then used either when creating the output linking section or to
 // synthesize the "__wasm_call_ctors" function.
 void Writer::calculateInitFunctions() {
   for (ObjFile *File : Symtab->ObjectFiles) {
     const WasmLinkingData &L = File->getWasmObj()->linkingData();
-    for (const WasmInitFunc &F : L.InitFunctions)
-      InitFunctions.emplace_back(
-          WasmInitEntry{File->getFunctionSymbol(F.Symbol), F.Priority});
+    for (const WasmInitFunc &F : L.InitFunctions) {
+      FunctionSymbol *Sym = File->getFunctionSymbol(F.Symbol);
+      if (*Sym->getFunctionType() != WasmSignature{{}, WASM_TYPE_NORESULT})
+        error("invalid signature for init func");
+      InitFunctions.emplace_back(WasmInitEntry{Sym, F.Priority});
+    }
   }
 
   // Sort in order of priority (lowest first) so that they are called
   // in the correct order.
   std::stable_sort(InitFunctions.begin(), InitFunctions.end(),
                    [](const WasmInitEntry &L, const WasmInitEntry &R) {
                      return L.Priority < R.Priority;
                    });