Fix parser error on block params (#6932)

The error checking we had to report an error when the input contains
block parameters was in a code path that is no longer executed under
normal circumstances. Specifically, it was part of the
`ParseModuleTypesCtx` phase of parsing, which no longer parses function
bodies. Move the error checking to the `ParseDefsCtx` phase, which does
parse function bodies.

Fixes #6929.

src/parser/contexts.h

@@ -1259,12 +1259,6 @@ struct ParseModuleTypesCtx : TypeParserCtx<ParseModuleTypesCtx>,
   }
 
   Result<HeapType> getBlockTypeFromTypeUse(Index pos, TypeUse use) {
-    assert(use.type.isSignature());
-    if (use.type.getSignature().params != Type::none) {
-      return in.err(pos, "block parameters not yet supported");
-    }
-    // TODO: Once we support block parameters, return an error here if any of
-    // them are named.
     return use.type;
   }
 
@@ -1451,6 +1445,12 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx> {
   }
 
   Result<HeapType> getBlockTypeFromTypeUse(Index pos, HeapType type) {
+    assert(type.isSignature());
+    if (type.getSignature().params != Type::none) {
+      return in.err(pos, "block parameters not yet supported");
+    }
+    // TODO: Once we support block parameters, return an error here if any of
+    // them are named.
     return type;
   }
 

test/lit/parse-bad-block-params.wast

@@ -0,0 +1,12 @@
+;; RUN: not wasm-opt %s -S -o - 2>&1 | filecheck %s
+
+;; CHECK: 8:11: error: block parameters not yet supported
+
+(module
+  (func
+    (i32.const 0)
+    (block (param i32)
+      (drop)
+    )
+  )
+)