Refactor Skylark Environment-s

Make Environment-s freezable: Introduce a class Mutability
as a revokable capability to mutate objects in an Environment.
For now, only Environment-s carry this capability.
Make sure that every Mutability is revoked in the same function that creates it,
so no Environment is left open for modification after being created and exported;
exceptions for tests, the shell and initialization contexts.

Unify Environment, SkylarkEnvironment and EvaluationContext into Environment.
Have a notion of Frame for the bindings + parent + mutability.
Replace the updateAndPropagate mechanism by a dynamicFrame.
Simplify ValidationEnvironment, that is now always deduced from the Environment.

--
MOS_MIGRATED_REVID=102363438

1 files changed, 11 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
index 94b1917ab6..6140acb0b0 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkCallbackFunction.java
@@ -22,21 +22,25 @@ public class SkylarkCallbackFunction {
 
   private final BaseFunction callback;
   private final FuncallExpression ast;
-  private final SkylarkEnvironment funcallEnv;
+  private final Environment funcallEnv;
 
-  public SkylarkCallbackFunction(BaseFunction callback, FuncallExpression ast,
-      SkylarkEnvironment funcallEnv) {
+  public SkylarkCallbackFunction(
+      BaseFunction callback, FuncallExpression ast, Environment funcallEnv) {
     this.callback = callback;
     this.ast = ast;
     this.funcallEnv = funcallEnv;
   }
 
   public Object call(ClassObject ctx, Object... arguments) throws EvalException {
-    try {
+    try (Mutability mutability = Mutability.create("callback %s", callback)) {
+      Environment env = Environment.builder(mutability)
+          .setSkylark()
+          .setEventHandler(funcallEnv.getEventHandler())
+          .setGlobals(funcallEnv.getGlobals())
+          .build();
       return callback.call(
-          ImmutableList.<Object>builder().add(ctx).add(arguments).build(), null, ast, funcallEnv);
-    } catch (InterruptedException | ClassCastException
-        | IllegalArgumentException e) {
+          ImmutableList.<Object>builder().add(ctx).add(arguments).build(), null, ast, env);
+    } catch (InterruptedException | ClassCastException | IllegalArgumentException e) {
       throw new EvalException(ast.getLocation(), e.getMessage());
     }
   }