Add experimental flag to stop requiring all transitive modules as inputs.

Requiring all transitive modules to always be available can lead to long
critical paths and even unnecessary compiles in combination with the
prune_header_modules feature.

--
MOS_MIGRATED_REVID=137696794

1 files changed, 10 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
index edf780dd76..becf653502 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
@@ -527,6 +527,16 @@ public class CppOptions extends FragmentOptions {
   public boolean inmemoryDotdFiles;
 
   @Option(
+    name = "experimental_skip_unused_modules",
+    defaultValue = "false",
+    category = "experimental",
+    help =
+        "If enabled, not all transitive modules automatically become an action's inputs. Instead,"
+            + " input discovery adds just the required ones."
+  )
+  public boolean skipUnusedModules;
+
+  @Option(
     name = "experimental_omitfp",
     defaultValue = "false",
     category = "semantics",