[clang][modules] Don't prevent translation of FW_Private includes when explicitly building FW (#70714)

We prevent translating `#include <FW/PrivateHeader.h>` into an import of
FW_Private when compiling the implementation of FW or FW_Private. This
is specified via `-fmodule-name=` on the TU command line (used to be
`-fmodule-implementation-of`).

This logic is supposed to only kick in when imported directly from a TU,
but it currently also kicks in when compiling the public FW module
explicitly (since it also has `-fmodule-name=` on the command line).

This patch makes sure this logic only kicks in for the case that used to
be `-fmodule-implementation-of` (for the TU), and not for all
`-fmodule-name=` cases (especially for the explicit compile of a
module).

rdar://101051277; related: rdar://37500098&38434694

1 files changed, 4 insertions, 3 deletions

diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index cc2e5be..e4ac1ab 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -161,9 +161,10 @@ bool Module::isForBuilding(const LangOptions &LangOpts) const {
   StringRef TopLevelName = getTopLevelModuleName();
   StringRef CurrentModule = LangOpts.CurrentModule;
 
-  // When building framework Foo, we want to make sure that Foo *and*
-  // Foo_Private are textually included and no modules are built for both.
-  if (getTopLevelModule()->IsFramework &&
+  // When building the implementation of framework Foo, we want to make sure
+  // that Foo *and* Foo_Private are textually included and no modules are built
+  // for either.
+  if (!LangOpts.isCompilingModule() && getTopLevelModule()->IsFramework &&
       CurrentModule == LangOpts.ModuleName &&
       !CurrentModule.endswith("_Private") && TopLevelName.endswith("_Private"))
     TopLevelName = TopLevelName.drop_back(8);