[PCH/Modules] Check that the specific module cache path the PCH was built with, is the same as

the one in the current compiler invocation. If they differ reject the PCH.

This protects against the badness occurring from getting modules loaded from different module caches (see crashes).

rdar://19889860

llvm-svn: 229909

clang/lib/Frontend/FrontendActions.cpp

@@ -501,9 +501,11 @@ namespace {
     }
 
     bool ReadHeaderSearchOptions(const HeaderSearchOptions &HSOpts,
+                                 StringRef SpecificModuleCachePath,
                                  bool Complain) override {
       Out.indent(2) << "Header search options:\n";
       Out.indent(4) << "System root [-isysroot=]: '" << HSOpts.Sysroot << "'\n";
+      Out.indent(4) << "Module Cache: '" << SpecificModuleCachePath << "'\n";
       DUMP_BOOLEAN(HSOpts.UseBuiltinIncludes,
                    "Use builtin include directories [-nobuiltininc]");
       DUMP_BOOLEAN(HSOpts.UseStandardSystemIncludes,