1 files changed, 48 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
new file mode 100644
index 00000000000..cb77e95fa81
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.cpp
@@ -0,0 +1,48 @@
+//===--- NoInternalDependenciesCheck.cpp - clang-tidy----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NoInternalDependenciesCheck.h"
+#include "AbseilMatcher.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+void NoInternalDependenciesCheck::registerMatchers(MatchFinder *Finder) {
+  if (!getLangOpts().CPlusPlus)
+    return;
+
+  // TODO: refactor matcher to be configurable or just match on any internal
+  // access from outside the enclosing namespace.
+
+  Finder->addMatcher(
+      nestedNameSpecifierLoc(loc(specifiesNamespace(namespaceDecl(
+                                 matchesName("internal"),
+                                 hasParent(namespaceDecl(hasName("absl")))))),
+                             unless(isInAbseilFile()))
+          .bind("InternalDep"),
+      this);
+}
+
+void NoInternalDependenciesCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *InternalDependency =
+      Result.Nodes.getNodeAs<NestedNameSpecifierLoc>("InternalDep");
+
+  diag(InternalDependency->getBeginLoc(),
+       "do not reference any 'internal' namespaces; those implementation "
+       "details are reserved to Abseil");
+}
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang