commit de62eddd42be8ccba7e7d908fb62e02dfeccb517
author ulfjack <ulfjack@google.com> Fri May 24 08:11:43 2019 -0700
committer Copybara-Service <copybara-worker@google.com> Fri May 24 08:13:05 2019 -0700
tree 2326cb3dad5e300c37abdbb9433f0f34aa1e82f1
parent b75e4530ee0d13683ae965939e1dfc475ef9ee21

Fix Objc pre-execution header thinning

It was accidentally disabled by https://github.com/bazelbuild/bazel/commit/51a9596f592c183beffdeeffc43c86295c88a4a5 due to the refactoring in
CppCompileAction that made it no longer call the include processing if
shouldScanIncludes() returned false.

Note that ObjC header thinning relies on needsDotdInputPruning being
true as controlled by the --objc_use_dotd_pruning flag. Note that bazel
emits an error if header thinning is enabled, but dotd pruning is
disabled.

This was not caught by our existing tests because none of them actually
check if the list of inputs to the action was reduced before it is
executed. The tests only check that the include scanning action returns
a reduced list, but not that the reduced list is actually used in the
CppCompileAction.

PiperOrigin-RevId: 249835036

src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
index b199335..d317dfd 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
@@ -401,17 +401,18 @@
   private Iterable<Artifact> findUsedHeaders(
       ActionExecutionContext actionExecutionContext, IncludeScanningHeaderData headerData)
       throws ActionExecutionException, InterruptedException {
-    if (!shouldScanIncludes()) {
-      return NestedSetBuilder.fromNestedSet(ccCompilationContext.getDeclaredIncludeSrcs())
-          .addTransitive(additionalPrunableHeaders)
-          .build();
-    }
     try {
       try {
-        return actionExecutionContext
-            .getContext(CppIncludeScanningContext.class)
-            .findAdditionalInputs(this, actionExecutionContext, includeProcessing, headerData)
-            .get();
+        ListenableFuture<Iterable<Artifact>> future =
+            actionExecutionContext
+                .getContext(CppIncludeScanningContext.class)
+                .findAdditionalInputs(this, actionExecutionContext, includeProcessing, headerData);
+        if (future == null) {
+          return NestedSetBuilder.fromNestedSet(ccCompilationContext.getDeclaredIncludeSrcs())
+              .addTransitive(additionalPrunableHeaders)
+              .build();
+        }
+        return future.get();
       } catch (ExecutionException e) {
         Throwables.throwIfInstanceOf(e.getCause(), ExecException.class);
         Throwables.throwIfInstanceOf(e.getCause(), InterruptedException.class);