[Modules] Add 'no_undeclared_includes' module map attribute

The 'no_undeclared_includes' attribute should be used in a module to
tell that only non-modular headers and headers from used modules are
accepted.

The main motivation behind this is to prevent dep cycles between system
libraries (such as darwin) and libc++.

Patch by Richard Smith!

llvm-svn: 284797

1 files changed, 36 insertions, 7 deletions

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index c85aaa2ecc0..d01881c1456 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -413,6 +413,12 @@ getTopFrameworkDir(FileManager &FileMgr, StringRef DirName,
   return TopFrameworkDir;
 }
 
+static bool needModuleLookup(Module *RequestingModule,
+                             bool HasSuggestedModule) {
+  return HasSuggestedModule ||
+         (RequestingModule && RequestingModule->NoUndeclaredIncludes);
+}
+
 /// DoFrameworkLookup - Do a lookup of the specified file in the current
 /// DirectoryLookup, which is a framework directory.
 const FileEntry *DirectoryLookup::DoFrameworkLookup(
@@ -508,7 +514,7 @@ const FileEntry *DirectoryLookup::DoFrameworkLookup(
   }
 
   // If we found the header and are allowed to suggest a module, do so now.
-  if (FE && SuggestedModule) {
+  if (FE && needModuleLookup(RequestingModule, SuggestedModule)) {
     // Find the framework in which this header occurs.
     StringRef FrameworkPath = FE->getDir()->getName();
     bool FoundFramework = false;
@@ -1158,22 +1164,45 @@ bool HeaderSearch::hasModuleMap(StringRef FileName,
 }
 
 ModuleMap::KnownHeader
-HeaderSearch::findModuleForHeader(const FileEntry *File) const {
+HeaderSearch::findModuleForHeader(const FileEntry *File,
+                                  bool AllowTextual) const {
   if (ExternalSource) {
     // Make sure the external source has handled header info about this file,
     // which includes whether the file is part of a module.
     (void)getExistingFileInfo(File);
   }
-  return ModMap.findModuleForHeader(File);
+  return ModMap.findModuleForHeader(File, AllowTextual);
+}
+
+static bool suggestModule(HeaderSearch &HS, const FileEntry *File,
+                          Module *RequestingModule,
+                          ModuleMap::KnownHeader *SuggestedModule) {
+  ModuleMap::KnownHeader Module =
+      HS.findModuleForHeader(File, /*AllowTextual*/true);
+  if (SuggestedModule)
+    *SuggestedModule = (Module.getRole() & ModuleMap::TextualHeader)
+                           ? ModuleMap::KnownHeader()
+                           : Module;
+
+  // If this module specifies [no_undeclared_includes], we cannot find any
+  // file that's in a non-dependency module.
+  if (RequestingModule && Module && RequestingModule->NoUndeclaredIncludes) {
+    HS.getModuleMap().resolveUses(RequestingModule, /*Complain*/false);
+    if (!RequestingModule->directlyUses(Module.getModule())) {
+      return false;
+    }
+  }
+
+  return true;
 }
 
 bool HeaderSearch::findUsableModuleForHeader(
     const FileEntry *File, const DirectoryEntry *Root, Module *RequestingModule,
     ModuleMap::KnownHeader *SuggestedModule, bool IsSystemHeaderDir) {
-  if (File && SuggestedModule) {
+  if (File && needModuleLookup(RequestingModule, SuggestedModule)) {
     // If there is a module that corresponds to this header, suggest it.
     hasModuleMap(File->getName(), Root, IsSystemHeaderDir);
-    *SuggestedModule = findModuleForHeader(File);
+    return suggestModule(*this, File, RequestingModule, SuggestedModule);
   }
   return true;
 }
@@ -1182,7 +1211,7 @@ bool HeaderSearch::findUsableModuleForFrameworkHeader(
     const FileEntry *File, StringRef FrameworkName, Module *RequestingModule,
     ModuleMap::KnownHeader *SuggestedModule, bool IsSystemFramework) {
   // If we're supposed to suggest a module, look for one now.
-  if (SuggestedModule) {
+  if (needModuleLookup(RequestingModule, SuggestedModule)) {
     // Find the top-level framework based on this framework.
     SmallVector<std::string, 4> SubmodulePath;
     const DirectoryEntry *TopFrameworkDir
@@ -1199,7 +1228,7 @@ bool HeaderSearch::findUsableModuleForFrameworkHeader(
     // important so that we're consistent about whether this header
     // corresponds to a module. Possibly we should lock down framework modules
     // so that this is not possible.
-    *SuggestedModule = findModuleForHeader(File);
+    return suggestModule(*this, File, RequestingModule, SuggestedModule);
   }
   return true;
 }