[Parser] Do not involve IRBuilder for imported functions (#6286)

We previously had a bug where we would begin and end an IRBuilder context for
imported functions even though they don't have bodies. For functions that return
results, ending this empty scope should have produced an error except that we
had another bug where we only produced that error for multivalue functions. We
did not previously have imported multivalue functions in wat-kitchen-sink.wast,
so both of these bugs went undetected. Fix both bugs and update the test to
include an imported multivalue function so that it would have failed without
this fix.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/wasm/wasm-ir-builder.cpp b/src/wasm/wasm-ir-builder.cpp
index 8098856e4..bf3c38c1e 100644
--- a/src/wasm/wasm-ir-builder.cpp
+++ b/src/wasm/wasm-ir-builder.cpp
@@ -162,7 +162,6 @@ Result<Expression*> IRBuilder::pop(size_t size) {
   // Find the suffix of expressions that do not produce values.
   auto hoisted = hoistLastValue();
   CHECK_ERR(hoisted);
-
   if (!hoisted) {
     // There are no expressions that produce values.
     if (scope.unreachable) {
@@ -700,6 +699,9 @@ Result<Expression*> IRBuilder::finishScope(Block* block) {
     // the top.
     auto hoisted = hoistLastValue();
     CHECK_ERR(hoisted);
+    if (!hoisted) {
+      return Err{"popping from empty stack"};
+    }
   }
 
   Expression* ret = nullptr;