Fix issue #1732 heapGraph crashes

scripts/test-runner.js

@@ -286,6 +286,7 @@ function runTest(name, code, options: PrepackOptions, args) {
   options.invariantLevel = code.includes("// omit invariants") || args.verbose ? 0 : 99;
   if (code.includes("// emit concrete model")) options.emitConcreteModel = true;
   if (code.includes("// exceeds stack limit")) options.maxStackDepth = 10;
+  if (code.includes("// heapGraphFilePath")) options.heapGraphFormat = "VISJS";
   if (code.includes("// react")) {
     options.reactEnabled = true;
     options.reactOutput = "jsx";

src/serializer/serializer.js

@@ -182,6 +182,9 @@ export class Serializer {
             additionalFunctionValuesAndEffects,
             referentializer
           );
+          // Copying dERB map so cache lookup returns the same object, and the subsequent
+          // invariant in ModifiedBindingEntry's visit() passes.
+          heapRefCounter.declarativeEnvironmentRecordsBindings = residualHeapVisitor.declarativeEnvironmentRecordsBindings;
           heapRefCounter.visitRoots();
 
           const heapGraphGenerator = new ResidualHeapGraphGenerator(
@@ -193,6 +196,7 @@ export class Serializer {
             heapRefCounter.getResult(),
             referentializer
           );
+          heapGraphGenerator.declarativeEnvironmentRecordsBindings = residualHeapVisitor.declarativeEnvironmentRecordsBindings;
           heapGraphGenerator.visitRoots();
           invariant(this.options.heapGraphFormat);
           heapGraph = heapGraphGenerator.generateResult(this.options.heapGraphFormat);

src/utils/generator.js

@@ -253,10 +253,11 @@ class ModifiedBindingEntry extends GeneratorEntry {
       containingGenerator === this.containingGenerator,
       "This entry requires effects to be applied and may not be moved"
     );
-    invariant(this.modifiedBinding.value === this.newValue);
+    invariant(this.modifiedBinding.value === this.newValue, "ModifiedBinding's value has been improperly modified.");
     let [residualBinding, newValue] = context.visitModifiedBinding(this.modifiedBinding);
-    invariant(this.residualFunctionBinding === undefined || this.residualFunctionBinding === residualBinding);
+    invariant(this.residualFunctionBinding === undefined || this.residualFunctionBinding === residualBinding, "ResidualFunctionBinding improperly mutated");
     this.residualFunctionBinding = residualBinding;
+    this.modifiedBinding.value = newValue;
     this.newValue = newValue;
     return true;
   }

test/serializer/additional-functions/heapGraph.js

@@ -0,0 +1,18 @@
+// Tests that code with heapgraph enabled doesn't crash.
+// Regression test for issue #1732.
+
+// heapGraphFilePath
+
+(function () {
+    let a = global.__abstract ? __abstract("number", "5") : 5;
+    let b, c;
+    global.f = function() {
+      b = a + 42;
+      c = a + 42;
+      return b;
+    }
+    global.__optimize && __optimize(f);
+
+})();
+
+inspect = function() { return global.f(); }