Modules: Add -Rmodule-import

Add a remark for importing modules.  Depending on whether this is a
direct import (into the TU being built by this compiler instance) or
transitive import (into an already-imported module), the diagnostic has
two forms:

    importing module 'Foo' from 'path/to/Foo.pcm'
    importing module 'Foo' into 'Bar' from 'path/to/Foo.pcm'

Also drop a redundant FileCheck invocation in Rmodule-build.m that was
using -Reverything, since the notes from -Rmodule-import were confusing
it.

https://reviews.llvm.org/D58891

llvm-svn: 355477
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 5ad2160..39df352 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2610,6 +2610,9 @@
 
     case MODULE_NAME:
       F.ModuleName = Blob;
+      Diag(diag::remark_module_import)
+          << F.ModuleName << F.FileName << (ImportedBy ? true : false)
+          << (ImportedBy ? StringRef(ImportedBy->ModuleName) : StringRef());
       if (Listener)
         Listener->ReadModuleName(F.ModuleName);
 
@@ -4141,6 +4144,9 @@
 
   switch (AddResult) {
   case ModuleManager::AlreadyLoaded:
+    Diag(diag::remark_module_import)
+        << M->ModuleName << M->FileName << (ImportedBy ? true : false)
+        << (ImportedBy ? StringRef(ImportedBy->ModuleName) : StringRef());
     return Success;
 
   case ModuleManager::NewlyLoaded: