[clang][modules] Allow module map files with textual header be non-affecting

Author: jansvoboda11

clang/lib/Serialization/ASTWriter.cpp

@@ -187,7 +187,8 @@ GetAffectingModuleMaps(const Preprocessor &PP, Module *RootModule) {
       continue;
 
     const HeaderFileInfo *HFI = HS.getExistingLocalFileInfo(*File);
-    if (!HFI || (HFI->isModuleHeader && !HFI->isCompilingModuleHeader))
+    if (!HFI || ((HFI->isModuleHeader || HFI->isTextualModuleHeader) &&
+                 !HFI->isCompilingModuleHeader))
       continue;
 
     for (const auto &KH : HS.findResolvedModulesForHeader(*File)) {
@@ -2055,11 +2056,12 @@ void ASTWriter::WriteHeaderSearch(const HeaderSearch &HS) {
 
     // Get the file info. Skip emitting this file if we have no information on
     // it as a header file (in which case HFI will be null) or if it hasn't
-    // changed since it was loaded. Also skip it if it's for a modular header
-    // from a different module; in that case, we rely on the module(s)
+    // changed since it was loaded. Also skip it if it's for a non-excluded
+    // header from a different module; in that case, we rely on the module(s)
     // containing the header to provide this information.
     const HeaderFileInfo *HFI = HS.getExistingLocalFileInfo(*File);
-    if (!HFI || (HFI->isModuleHeader && !HFI->isCompilingModuleHeader))
+    if (!HFI || ((HFI->isModuleHeader || HFI->isTextualModuleHeader) &&
+                 !HFI->isCompilingModuleHeader))
       continue;
 
     // Massage the file path into an appropriate form.

clang/test/Modules/prune-non-affecting-module-map-files-textual.c

@@ -0,0 +1,26 @@
+// This test checks that a module map with a textual header can be marked as
+// non-affecting.
+
+// RUN: rm -rf %t && mkdir %t
+// RUN: split-file %s %t
+
+//--- A.modulemap
+module A { textual header "A.h" }
+//--- B.modulemap
+module B { header "B.h" export * }
+//--- A.h
+typedef int A_int;
+//--- B.h
+#include "A.h"
+typedef A_int B_int;
+
+// RUN: %clang_cc1 -fmodules -emit-module %t/A.modulemap -fmodule-name=A -o %t/A.pcm \
+// RUN:   -fmodule-map-file=%t/A.modulemap -fmodule-map-file=%t/B.modulemap
+
+// RUN: %clang_cc1 -fmodules -emit-module %t/B.modulemap -fmodule-name=B -o %t/B0.pcm \
+// RUN:   -fmodule-map-file=%t/A.modulemap -fmodule-map-file=%t/B.modulemap -fmodule-file=%t/A.pcm
+
+// RUN: %clang_cc1 -fmodules -emit-module %t/B.modulemap -fmodule-name=B -o %t/B1.pcm \
+// RUN:                                    -fmodule-map-file=%t/B.modulemap -fmodule-file=%t/A.pcm
+
+// RUN: diff %t/B0.pcm %t/B1.pcm