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, 25 insertions, 15 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ASTFileLookupFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ASTFileLookupFunction.java
index 2b339046e0..fe44617e02 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ASTFileLookupFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ASTFileLookupFunction.java
@@ -20,6 +20,9 @@ import com.google.devtools.build.lib.packages.CachingPackageLocator;
 import com.google.devtools.build.lib.packages.RuleClassProvider;
 import com.google.devtools.build.lib.pkgcache.PathPackageLocator;
 import com.google.devtools.build.lib.syntax.BuildFileAST;
+import com.google.devtools.build.lib.syntax.Mutability;
+import com.google.devtools.build.lib.syntax.Runtime;
+import com.google.devtools.build.lib.syntax.ValidationEnvironment;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.lib.vfs.RootedPath;
@@ -113,26 +116,33 @@ public class ASTFileLookupFunction implements SkyFunction {
     if (lookupResult == null) {
       return null;
     }
-
-    BuildFileAST ast = null;
     if (!lookupResult.lookupSuccessful()) {
       return ASTFileLookupValue.noFile();
-    } else {
-      Path path = lookupResult.rootedPath().asPath();
-      // Skylark files end with bzl.
-      boolean parseAsSkylark = astFilePathFragment.getPathString().endsWith(".bzl");
-      try {
-        ast = parseAsSkylark
-            ? BuildFileAST.parseSkylarkFile(path, env.getListener(),
-                packageManager, ruleClassProvider.getSkylarkValidationEnvironment().clone())
-            : BuildFileAST.parseBuildFile(path, env.getListener(),
-                packageManager, false);
-      } catch (IOException e) {
+    }
+    BuildFileAST ast = null;
+    Path path = lookupResult.rootedPath().asPath();
+    // Skylark files end with bzl.
+    boolean parseAsSkylark = astFilePathFragment.getPathString().endsWith(".bzl");
+    try {
+      if (parseAsSkylark) {
+        try (Mutability mutability = Mutability.create("validate")) {
+            ast = BuildFileAST.parseSkylarkFile(path, env.getListener(),
+                packageManager, new ValidationEnvironment(
+                    ruleClassProvider.createSkylarkRuleClassEnvironment(
+                        mutability,
+                        env.getListener(),
+                        // the two below don't matter for extracting the ValidationEnvironment:
+                        /*astFileContentHashCode=*/null,
+                        /*importMap=*/null)
+                    .setupDynamic(Runtime.PKG_NAME, Runtime.NONE)));
+        }
+      } else {
+        ast = BuildFileAST.parseBuildFile(path, env.getListener(), packageManager, false);
+      }
+    } catch (IOException e) {
         throw new ASTLookupFunctionException(new ErrorReadingSkylarkExtensionException(
             e.getMessage()), Transience.TRANSIENT);
-      }
     }
-
     return ASTFileLookupValue.withFile(ast);
   }