Add the readability-redundant-access-specifiers check.

This finds redundant access specifier declarations inside classes, structs, and unions.

Patch by Mateusz Mackowski.

4 files changed, 128 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
index 2d226b1..7455e10 100644
--- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
@@ -21,6 +21,7 @@ add_clang_library(clangTidyReadabilityModule
   NamespaceCommentCheck.cpp
   NonConstParameterCheck.cpp
   ReadabilityTidyModule.cpp
+  RedundantAccessSpecifiersCheck.cpp
   RedundantControlFlowCheck.cpp
   RedundantDeclarationCheck.cpp
   RedundantFunctionPtrDereferenceCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
index 5005ba3..2fd2870 100644
--- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -27,6 +27,7 @@
 #include "MisplacedArrayIndexCheck.h"
 #include "NamedParameterCheck.h"
 #include "NonConstParameterCheck.h"
+#include "RedundantAccessSpecifiersCheck.h"
 #include "RedundantControlFlowCheck.h"
 #include "RedundantDeclarationCheck.h"
 #include "RedundantFunctionPtrDereferenceCheck.h"
@@ -82,6 +83,8 @@ public:
         "readability-misleading-indentation");
     CheckFactories.registerCheck<MisplacedArrayIndexCheck>(
         "readability-misplaced-array-index");
+    CheckFactories.registerCheck<RedundantAccessSpecifiersCheck>(
+        "readability-redundant-access-specifiers");
     CheckFactories.registerCheck<RedundantFunctionPtrDereferenceCheck>(
         "readability-redundant-function-ptr-dereference");
     CheckFactories.registerCheck<RedundantMemberInitCheck>(
diff --git a/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
new file mode 100644
index 0000000..22625c9
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.cpp
@@ -0,0 +1,85 @@
+//===--- RedundantAccessSpecifiersCheck.cpp - clang-tidy ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "RedundantAccessSpecifiersCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+void RedundantAccessSpecifiersCheck::registerMatchers(MatchFinder *Finder) {
+  if (!getLangOpts().CPlusPlus)
+    return;
+
+  Finder->addMatcher(
+      cxxRecordDecl(has(accessSpecDecl())).bind("redundant-access-specifiers"),
+      this);
+}
+
+void RedundantAccessSpecifiersCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *MatchedDecl =
+      Result.Nodes.getNodeAs<CXXRecordDecl>("redundant-access-specifiers");
+
+  const AccessSpecDecl *LastASDecl = nullptr;
+  for (DeclContext::specific_decl_iterator<AccessSpecDecl>
+           AS(MatchedDecl->decls_begin()),
+       ASEnd(MatchedDecl->decls_end());
+       AS != ASEnd; ++AS) {
+    const AccessSpecDecl *ASDecl = *AS;
+
+    // Ignore macro expansions.
+    if (ASDecl->getLocation().isMacroID()) {
+      LastASDecl = ASDecl;
+      continue;
+    }
+
+    if (LastASDecl == nullptr) {
+      // First declaration.
+      LastASDecl = ASDecl;
+
+      if (CheckFirstDeclaration) {
+        AccessSpecifier DefaultSpecifier =
+            MatchedDecl->isClass() ? AS_private : AS_public;
+        if (ASDecl->getAccess() == DefaultSpecifier) {
+          diag(ASDecl->getLocation(),
+               "redundant access specifier has the same accessibility as the "
+               "implicit access specifier")
+              << FixItHint::CreateRemoval(ASDecl->getSourceRange());
+        }
+      }
+
+      continue;
+    }
+
+    if (LastASDecl->getAccess() == ASDecl->getAccess()) {
+      // Ignore macro expansions.
+      if (LastASDecl->getLocation().isMacroID()) {
+        LastASDecl = ASDecl;
+        continue;
+      }
+
+      diag(ASDecl->getLocation(),
+           "redundant access specifier has the same accessibility as the "
+           "previous access specifier")
+          << FixItHint::CreateRemoval(ASDecl->getSourceRange());
+      diag(LastASDecl->getLocation(), "previously declared here",
+           DiagnosticIDs::Note);
+    } else {
+      LastASDecl = ASDecl;
+    }
+  }
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.h b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.h
new file mode 100644
index 0000000..2aee22f
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/RedundantAccessSpecifiersCheck.h
@@ -0,0 +1,39 @@
+//===--- RedundantAccessSpecifiersCheck.h - clang-tidy ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTACCESSSPECIFIERSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTACCESSSPECIFIERSCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+/// Detects redundant access specifiers inside classes, structs, and unions.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability-redundant-access-specifiers.html
+class RedundantAccessSpecifiersCheck : public ClangTidyCheck {
+public:
+  RedundantAccessSpecifiersCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context),
+        CheckFirstDeclaration(
+            Options.getLocalOrGlobal("CheckFirstDeclaration", false)) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  const bool CheckFirstDeclaration;
+};
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTACCESSSPECIFIERSCHECK_H