break type system fixes, avoid spurious errors on mismatched types

2 files changed, 9 insertions, 3 deletions

diff --git a/src/wasm-validator.h b/src/wasm-validator.h
index 49e2eb5d8..3d9693421 100644
--- a/src/wasm-validator.h
+++ b/src/wasm-validator.h
@@ -71,8 +71,10 @@ public:
     } else {
       if (breakTypes[name] == unreachable) {
         breakTypes[name] = valueType;
-      } else {
-        shouldBeEqual(valueType, breakTypes[name], name.str, "breaks to same target must have same type (ignoring unreachable)");
+      } else if (valueType != unreachable) {
+        if (valueType != breakTypes[name]) {
+          breakTypes[name] = none; // a poison value that must not be consumed
+        }
       }
     }
   }
diff --git a/src/wasm.cpp b/src/wasm.cpp
index 2157992e3..98268310a 100644
--- a/src/wasm.cpp
+++ b/src/wasm.cpp
@@ -33,7 +33,11 @@ struct BlockTypeSeeker : public PostWalker<BlockTypeSeeker, Visitor<BlockTypeSee
       if (other == none) {
         type = none;
       } else if (other != unreachable) {
-        type = other;
+        if (type == unreachable) {
+          type = other;
+        } else if (type != other) {
+          type = none; // poison value, we saw multiple types; this should not be consumed
+        }
       }
     }
   }