[PCH] Fix a regression when PCH is used with -fmodules

Following up on r291465 after a regression in r276159. When we use
-fmodule-name=X while building a PCH, modular headers in X will be
textually included and the compiler knows that we are not building
module X, so don't serialize such headers in the PCH as being part of a
module, because at this point they are not.

This was causing subtle bugs and malformed AST crashes, for instance,
when using the PCH in subsequent compiler invocation with -fmodules, the
HFI for a modular header would map to the PCH, which would force a
module load of and unexistent module ID.

rdar://problem/30171164

llvm-svn: 294361

clang/lib/Serialization/ASTWriter.cpp

@@ -2544,7 +2544,8 @@ unsigned ASTWriter::getLocalOrImportedSubmoduleID(Module *Mod) {
 
   auto *Top = Mod->getTopLevelModule();
   if (Top != WritingModule &&
-      !Top->fullModuleNameIs(StringRef(getLangOpts().CurrentModule)))
+      (getLangOpts().CompilingPCH ||
+       !Top->fullModuleNameIs(StringRef(getLangOpts().CurrentModule))))
     return 0;
 
   return SubmoduleIDs[Mod] = NextSubmoduleID++;

clang/test/Modules/Inputs/invalid-module-id/NC-Prefix.pch

@@ -0,0 +1,3 @@
+#ifdef __OBJC__
+  #import <NC/NULog.h>
+#endif

clang/test/Modules/Inputs/invalid-module-id/NC.framework/Headers/NC.h

@@ -0,0 +1 @@
+#import <NC/NUGeometry.h>

clang/test/Modules/Inputs/invalid-module-id/NC.framework/Headers/NU-Visibility.h

@@ -0,0 +1 @@
+// NU-Visibility.h

clang/test/Modules/Inputs/invalid-module-id/NC.framework/Headers/NUGeometry.h

@@ -0,0 +1 @@
+#import <NC/NU-Visibility.h>

clang/test/Modules/Inputs/invalid-module-id/NC.framework/Modules/module.modulemap

@@ -0,0 +1,6 @@
+framework module NC {
+  umbrella header "NC.h"
+
+  export *
+  module * { export * }
+}

clang/test/Modules/Inputs/invalid-module-id/NC.framework/Modules/module.private.modulemap

@@ -0,0 +1,5 @@
+explicit module NC.Private
+{
+	header "NULog.h"
+	header "NUAssert.h"
+}

clang/test/Modules/Inputs/invalid-module-id/NC.framework/PrivateHeaders/NUAssert.h

@@ -0,0 +1 @@
+#import <NC/NULog.h>

clang/test/Modules/Inputs/invalid-module-id/NC.framework/PrivateHeaders/NULog.h

@@ -0,0 +1 @@
+#import <NC/NU-Visibility.h>

clang/test/Modules/invalid-pch-module-id.m

@@ -0,0 +1,13 @@
+// RUN: rm -rf %t.cache
+//
+// RUN: %clang_cc1 -x objective-c-header -fmodules -F%S/Inputs/invalid-module-id \
+// RUN:  -fmodule-implementation-of NC -fmodules-cache-path=%t.cache \
+// RUN:  -fimplicit-module-maps \
+// RUN:  -emit-pch %S/Inputs/invalid-module-id/NC-Prefix.pch -o %t.pch
+//
+// RUN: %clang_cc1 -x objective-c -fmodules -F%S/Inputs/invalid-module-id \
+// RUN:  -fmodule-implementation-of NC -fmodules-cache-path=%t.cache \
+// RUN:  -fimplicit-module-maps -include-pch %t.pch %s -fsyntax-only
+
+#import <NC/NULog.h>
+#import <NC/NUGeometry.h>