[Modules][ObjC] Warn on the use of '@import' in framework headers

Using @import in framework headers inhibit the use of such headers
when not using modules, this is specially bad for headers that end
up in the SDK (or any other system framework). Add a warning to give
users some indication that this is discouraged.

rdar://problem/39192894

llvm-svn: 335780

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index d925510..d1c3535 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -20,6 +20,7 @@
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
+#include "llvm/Support/Path.h"
 using namespace clang;
 
 
@@ -2123,6 +2124,7 @@ Decl *Parser::ParseModuleImport(SourceLocation AtLoc) {
   assert((AtLoc.isInvalid() ? Tok.is(tok::kw_import)
                             : Tok.isObjCAtKeyword(tok::objc_import)) &&
          "Improper start to module import");
+  bool IsObjCAtImport = Tok.isObjCAtKeyword(tok::objc_import);
   SourceLocation ImportLoc = ConsumeToken();
   SourceLocation StartLoc = AtLoc.isInvalid() ? ImportLoc : AtLoc;
   
@@ -2146,6 +2148,16 @@ Decl *Parser::ParseModuleImport(SourceLocation AtLoc) {
   if (Import.isInvalid())
     return nullptr;
 
+  // Using '@import' in framework headers requires modules to be enabled so that
+  // the header is parseable. Emit a warning to make the user aware.
+  if (IsObjCAtImport && AtLoc.isValid()) {
+    auto &SrcMgr = PP.getSourceManager();
+    auto *FE = SrcMgr.getFileEntryForID(SrcMgr.getFileID(AtLoc));
+    if (FE && llvm::sys::path::parent_path(FE->getDir()->getName())
+                  .endswith(".framework"))
+      Diags.Report(AtLoc, diag::warn_atimport_in_framework_header);
+  }
+
   return Import.get();
 }