Add '#pragma clang __debug module_map module.name' to dump the module
map being used for the module 'module.name'.

llvm-svn: 358632
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index fa8a797..5c567f2 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -561,6 +561,8 @@
   "unexpected debug command '%0'">, InGroup<IgnoredPragmas>;
 def warn_pragma_debug_missing_argument : Warning<
   "missing argument to debug command '%0'">, InGroup<IgnoredPragmas>;
+def warn_pragma_debug_unknown_module : Warning<
+  "unknown module '%0'">, InGroup<IgnoredPragmas>;
 // #pragma module
 def err_pp_expected_module_name : Error<
   "expected %select{identifier after '.' in |}0module name">;
diff --git a/clang/lib/Lex/Pragma.cpp b/clang/lib/Lex/Pragma.cpp
index 1c87f3e..ba1b73e 100644
--- a/clang/lib/Lex/Pragma.cpp
+++ b/clang/lib/Lex/Pragma.cpp
@@ -1010,7 +1010,7 @@
   PragmaDebugHandler() : PragmaHandler("__debug") {}
 
   void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
-                    Token &DepToken) override {
+                    Token &DebugToken) override {
     Token Tok;
     PP.LexUnexpandedToken(Tok);
     if (Tok.isNot(tok::identifier)) {
@@ -1072,6 +1072,22 @@
       else
         PP.Diag(MacroName, diag::warn_pragma_debug_missing_argument)
             << II->getName();
+    } else if (II->isStr("module_map")) {
+      llvm::SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 8>
+          ModuleName;
+      if (LexModuleName(PP, Tok, ModuleName))
+        return;
+      ModuleMap &MM = PP.getHeaderSearchInfo().getModuleMap();
+      Module *M = nullptr;
+      for (auto IIAndLoc : ModuleName) {
+        M = MM.lookupModuleQualified(IIAndLoc.first->getName(), M);
+        if (!M) {
+          PP.Diag(IIAndLoc.second, diag::warn_pragma_debug_unknown_module)
+              << IIAndLoc.first;
+          return;
+        }
+      }
+      M->dump();
     } else if (II->isStr("overflow_stack")) {
       DebugOverflowStack();
     } else if (II->isStr("handle_crash")) {