wasm2js: fix printing of negated negative constants (#2034)

It is invalid to print --5, we need to add a space - -5 so that it is valid JS to parse.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/emscripten-optimizer/simple_ast.h b/src/emscripten-optimizer/simple_ast.h
index 969277466..ded8af5f4 100644
--- a/src/emscripten-optimizer/simple_ast.h
+++ b/src/emscripten-optimizer/simple_ast.h
@@ -986,6 +986,9 @@ struct JSPrinter {
   }
 
   void printNum(Ref node) {
+    if (node->getNumber() < 0 && buffer[used-1] == '-') {
+      emit(' '); // cannot join - and - to --, looks like the -- operator
+    }
     emit(numToString(node->getNumber(), finalize));
   }