[clang-tidy] Add abseil-no-internal-dependencies check

Finds instances where the user depends on internal details and warns them against doing so.
Should not be run on internal Abseil files or Abseil source code.

Patch by hugoeg!

Differential Revision: https://reviews.llvm.org/D50542

llvm-svn: 340928

10 files changed, 196 insertions, 2 deletions

diff --git a/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp b/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
index e7e0a2bdc3c..b3de5c0799e 100644
--- a/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/AbseilTidyModule.cpp
@@ -12,6 +12,7 @@
 #include "../ClangTidyModuleRegistry.h"
 #include "DurationDivisionCheck.h"
 #include "FasterStrsplitDelimiterCheck.h"
+#include "NoInternalDependenciesCheck.h"
 #include "NoNamespaceCheck.h"
 #include "RedundantStrcatCallsCheck.h"
 #include "StringFindStartswithCheck.h"
@@ -28,6 +29,8 @@ public:
         "abseil-duration-division");
     CheckFactories.registerCheck<FasterStrsplitDelimiterCheck>(
         "abseil-faster-strsplit-delimiter");
+    CheckFactories.registerCheck<NoInternalDependenciesCheck>(
+        "abseil-no-internal-dependencies");
     CheckFactories.registerCheck<NoNamespaceCheck>("abseil-no-namespace");
     CheckFactories.registerCheck<RedundantStrcatCallsCheck>(
         "abseil-redundant-strcat-calls");
diff --git a/clang-tools-extra/clang-tidy/abseil/CMakeLists.txt b/clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
index f36c0d979ec..e268b34bf81 100644
--- a/clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/abseil/CMakeLists.txt
@@ -4,6 +4,7 @@ add_clang_library(clangTidyAbseilModule
   AbseilTidyModule.cpp
   DurationDivisionCheck.cpp
   FasterStrsplitDelimiterCheck.cpp
+  NoInternalDependenciesCheck.cpp
   NoNamespaceCheck.cpp
   RedundantStrcatCallsCheck.cpp
   StringFindStartswithCheck.cpp
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
diff --git a/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.h b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.h
new file mode 100644
index 00000000000..7e659df5908
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/abseil/NoInternalDependenciesCheck.h
@@ -0,0 +1,36 @@
+//===--- NoInternalDependenciesCheck.h - clang-tidy----------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_NOINTERNALDEPSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_NOINTERNALDEPSCHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace abseil {
+
+/// Finds instances where the user depends on internal details and warns them
+/// against doing so.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/abseil-no-internal-dependencies.html
+class NoInternalDependenciesCheck : public ClangTidyCheck {
+public:
+  NoInternalDependenciesCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace abseil
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ABSEIL_NOINTERNALDEPSCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1e3a74abedc..c660bc762a1 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -70,6 +70,11 @@ Improvements to clang-tidy
   Finds instances of ``absl::StrSplit()`` or ``absl::MaxSplits()`` where the
   delimiter is a single character string literal and replaces with a character.
 
+- New :doc:`abseil-no-internal-dependencies
+  <clang-tidy/checks/abseil-no-internal-dependencies>` check.
+  
+  Gives a warning if code using Abseil depends on internal details.
+
 - New :doc:`abseil-no-namespace
   <clang-tidy/checks/abseil-no-namespace>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/abseil-no-internal-dependencies.rst b/clang-tools-extra/docs/clang-tidy/checks/abseil-no-internal-dependencies.rst
new file mode 100644
index 00000000000..bcf68ffd2d5
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/abseil-no-internal-dependencies.rst
@@ -0,0 +1,24 @@
+subl.. title:: clang-tidy - abseil-no-internal-dependencies
+
+abseil-no-internal-dependencies
+===============================
+
+Warns if code using Abseil depends on internal details. If something is in a
+namespace that includes the word “internal”, code is not allowed to depend upon
+it beaucse it’s an implementation detail. They cannot friend it, include it,
+you mention it or refer to it in any way. Doing so violates Abseil's
+compatibility guidelines and may result in breakage. See
+https://abseil.io/about/compatibility for more information.
+
+The following cases will result in warnings:
+
+.. code-block:: c++
+
+  absl::strings_internal::foo();
+  // warning triggered on this line
+  class foo {
+    friend struct absl::container_internal::faa;
+    // warning triggered on this line
+  };
+  absl::memory_internal::MakeUniqueResult();
+  // warning triggered on this line
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 35deccd8e96..600969fbdd6 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -6,6 +6,7 @@ Clang-Tidy Checks
 .. toctree::
    abseil-duration-division
    abseil-faster-strsplit-delimiter
+   abseil-no-internal-dependencies
    abseil-no-namespace
    abseil-redundant-strcat-calls
    abseil-string-find-startswith
diff --git a/clang-tools-extra/test/clang-tidy/Inputs/absl/external-file.h b/clang-tools-extra/test/clang-tidy/Inputs/absl/external-file.h
index 94f6687b501..11e2e4aa96c 100644
--- a/clang-tools-extra/test/clang-tidy/Inputs/absl/external-file.h
+++ b/clang-tools-extra/test/clang-tidy/Inputs/absl/external-file.h
@@ -1 +1,6 @@
-namespace absl {}
+namespace absl {
+namespace base_internal {
+void InternalFunction() {}
+} // namespace base_internal 
+} //namespace absl
+void DirectAccess2() { absl::base_internal::InternalFunction(); }
diff --git a/clang-tools-extra/test/clang-tidy/Inputs/absl/strings/internal-file.h b/clang-tools-extra/test/clang-tidy/Inputs/absl/strings/internal-file.h
index 94f6687b501..6014278e260 100644
--- a/clang-tools-extra/test/clang-tidy/Inputs/absl/strings/internal-file.h
+++ b/clang-tools-extra/test/clang-tidy/Inputs/absl/strings/internal-file.h
@@ -1 +1,33 @@
-namespace absl {}
+namespace std {
+struct string {
+  string(const char *);
+  ~string();
+};
+} // namespace std
+
+namespace absl {
+std::string StringsFunction(std::string s1) { return s1; }
+class SomeContainer {};
+namespace strings_internal {
+void InternalFunction() {}
+template <class P> P InternalTemplateFunction(P a) {}
+} // namespace strings_internal
+
+namespace container_internal {
+struct InternalStruct {};
+} // namespace container_internal
+} // namespace absl
+
+// should not trigger warnings because inside Abseil files
+void DirectAcessInternal() {
+  absl::strings_internal::InternalFunction();
+  absl::strings_internal::InternalTemplateFunction<std::string>("a");
+}
+
+class FriendUsageInternal {
+  friend struct absl::container_internal::InternalStruct;
+};
+
+namespace absl {
+void OpeningNamespaceInternally() { strings_internal::InternalFunction(); }
+} // namespace absl
diff --git a/clang-tools-extra/test/clang-tidy/abseil-no-internal-dependencies.cpp b/clang-tools-extra/test/clang-tidy/abseil-no-internal-dependencies.cpp
new file mode 100644
index 00000000000..bd56cb04df7
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/abseil-no-internal-dependencies.cpp
@@ -0,0 +1,39 @@
+// RUN: %check_clang_tidy %s abseil-no-internal-dependencies %t,  -- -- -I %S/Inputs
+// RUN: clang-tidy -checks='-*, abseil-no-internal-dependencies' -header-filter='.*' %s -- -I %S/Inputs 2>&1 | FileCheck %s
+
+#include "absl/strings/internal-file.h"
+// CHECK-NOT: warning:
+
+#include "absl/external-file.h"
+// CHECK: absl/external-file.h:6:24: warning: do not reference any 'internal' namespaces; those implementation details are reserved to Abseil [abseil-no-internal-dependencies]
+
+void DirectAcess() {
+  absl::strings_internal::InternalFunction();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not reference any 'internal' namespaces; those implementation details are reserved to Abseil
+
+  absl::strings_internal::InternalTemplateFunction<std::string>("a");
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not reference any 'internal' namespaces; those implementation details are reserved to Abseil
+}
+
+class FriendUsage {
+  friend struct absl::container_internal::InternalStruct;
+  // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: do not reference any 'internal' namespaces; those implementation details are reserved to Abseil
+};
+
+namespace absl {
+void OpeningNamespace() {
+  strings_internal::InternalFunction();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not reference any 'internal' namespaces; those implementation details are reserved to Abseil
+}
+} // namespace absl
+
+// should not trigger warnings
+void CorrectUsage() {
+  std::string Str = absl::StringsFunction("a");
+  absl::SomeContainer b;
+}
+
+namespace absl {
+SomeContainer b;
+std::string Str = absl::StringsFunction("a");
+} // namespace absl