Validate drop

src/wasm-validator.h

@@ -303,12 +303,7 @@ struct WasmValidator : public PostWalker<WasmValidator, Visitor<WasmValidator>>
   }
 
   void visitDrop(Drop* curr) {
-    // TODO: assert on this, when tests pass
-    if (getenv("BINARYEN_WARN_DROP")) {
-      if (!(isConcreteWasmType(curr->value->type) || curr->value->type == unreachable)) {
-        std::cerr << "warning: bad drop " << curr << " in " << (getFunction() ? getFunction()->name : Name("?")) << '\n';
-      }
-    }
+    shouldBeTrue(isConcreteWasmType(curr->value->type) || curr->value->type == unreachable, curr, "can only drop a valid value");
   }
 
   void visitReturn(Return* curr) {

test/passes/vacuum.txt

@@ -145,17 +145,17 @@
   )
   (func $if-drop (type $3) (result i32)
     (block $out
-      (drop
-        (if
-          (call $if-drop)
+      (if
+        (call $if-drop)
+        (drop
           (call $int)
-          (br $out)
         )
+        (br $out)
       )
-      (drop
-        (if
-          (call $if-drop)
-          (br $out)
+      (if
+        (call $if-drop)
+        (br $out)
+        (drop
           (call $int)
         )
       )

test/passes/vacuum.wast

@@ -302,13 +302,15 @@
   (func $if-drop (result i32)
     (block $out
       (drop
-        (if (call $if-drop)
+        (if i32
+          (call $if-drop)
           (call $int)
           (br $out)
         )
       )
       (drop
-        (if (call $if-drop)
+        (if i32
+          (call $if-drop)
           (br $out)
           (call $int)
         )