For compilations with C++ modules, treat private headers (header files in

'srcs') as textually included headers.

A private header is never exported to a different module and thus cannot be
used by a different module. We never need to compile a module just because one
of it's private headers is used from somewhere else. There must be a different
cc_library (and thus module) that exports the header.

At the same time, being compiled into a module doesn't provide benefits for the
compilation of that cc_library itself, because a module created for a
cc_library A is never used when compiling any of A's srcs.

PiperOrigin-RevId: 197846388

2 files changed, 2 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
index 5b782ef492..611193a5a7 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
@@ -950,7 +950,7 @@ public final class CcCompilationHelper {
     ccCompilationContextBuilder.addDeclaredIncludeSrcs(additionalInputs);
     ccCompilationContextBuilder.addNonCodeInputs(additionalInputs);
     ccCompilationContextBuilder.addModularHdrs(publicHeaders.getHeaders());
-    ccCompilationContextBuilder.addModularHdrs(privateHeaders);
+    ccCompilationContextBuilder.addTextualHdrs(privateHeaders);
     ccCompilationContextBuilder.addTextualHdrs(publicTextualHeaders);
     ccCompilationContextBuilder.addPregreppedHeaders(
         CppHelper.createExtractInclusions(ruleContext, semantics, publicHeaders.getHeaders()));
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java
index 602089b691..05d78cf745 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModuleMapAction.java
@@ -140,7 +140,7 @@ public final class CppModuleMapAction extends AbstractFileWriteAction {
                 "private",
                 artifact.getExecPath(),
                 leadingPeriods,
-                /*canCompile=*/ true,
+                /*canCompile=*/ false,
                 deduper,
                 /*isUmbrellaHeader*/ false);
           }