asm2wasm: properly infer return type of a call inside a sequence (#1006)

1 files changed, 8 insertions, 2 deletions

diff --git a/src/asm2wasm.h b/src/asm2wasm.h
index 2fbe4d0ae..6327920fe 100644
--- a/src/asm2wasm.h
+++ b/src/asm2wasm.h
@@ -478,8 +478,14 @@ private:
   }
 
   FunctionType* getFunctionType(Ref parent, ExpressionList& operands) {
-    // generate signature
-    WasmType result = !!parent ? detectWasmType(parent, nullptr) : none;
+    WasmType result = none;
+    if (!!parent) {
+      // if the parent is a seq, we cannot be the last element in it (we would have a coercion, which would be
+      // the parent), so we must be (us, somethingElse), and so our return is void
+      if (parent[0] != SEQ) {
+        result = detectWasmType(parent, nullptr);
+      }
+    }
     return ensureFunctionType(getSig(result, operands), &wasm);
   }