Introduce '-fmodules-user-build-path' which accepts the "canonical" path to a user workspace build.

This is used to avoid conflicts with user modules with the same name from different workspaces.

rdar://16042513

llvm-svn: 202683

clang/lib/Frontend/CompilerInvocation.cpp

@@ -918,6 +918,7 @@ static void ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args) {
     Opts.UseLibcxx = (strcmp(A->getValue(), "libc++") == 0);
   Opts.ResourceDir = Args.getLastArgValue(OPT_resource_dir);
   Opts.ModuleCachePath = Args.getLastArgValue(OPT_fmodules_cache_path);
+  Opts.ModuleUserBuildPath = Args.getLastArgValue(OPT_fmodules_user_build_path);
   Opts.DisableModuleHash = Args.hasArg(OPT_fdisable_module_hash);
   // -fmodules implies -fmodule-maps
   Opts.ModuleMaps = Args.hasArg(OPT_fmodule_maps) || Args.hasArg(OPT_fmodules);
@@ -1821,6 +1822,9 @@ std::string CompilerInvocation::getModuleHash() const {
                       hsOpts.UseStandardCXXIncludes,
                       hsOpts.UseLibcxx);
 
+  // Extend the signature with the user build path.
+  code = hash_combine(code, hsOpts.ModuleUserBuildPath);
+
   // Darwin-specific hack: if we have a sysroot, use the contents and
   // modification time of
   //   $sysroot/System/Library/CoreServices/SystemVersion.plist