[clang-tidy] Add new readability non-idiomatic static access check

Patch by: Lilla Barancsuk

Differential Revision: https://reviews.llvm.org/D35937

llvm-svn: 310371

1 files changed, 90 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp b/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
new file mode 100644
index 00000000000..b1365772b59
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/StaticAccessedThroughInstanceCheck.cpp
@@ -0,0 +1,90 @@
+//===--- StaticAccessedThroughInstanceCheck.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 "StaticAccessedThroughInstanceCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+static unsigned getNameSpecifierNestingLevel(const QualType &QType) {
+  if (const ElaboratedType *ElType = QType->getAs<ElaboratedType>()) {
+    const NestedNameSpecifier *NestedSpecifiers = ElType->getQualifier();
+    unsigned NameSpecifierNestingLevel = 1;
+    do {
+      NameSpecifierNestingLevel++;
+      NestedSpecifiers = NestedSpecifiers->getPrefix();
+    } while (NestedSpecifiers);
+
+    return NameSpecifierNestingLevel;
+  }
+  return 0;
+}
+
+void StaticAccessedThroughInstanceCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "NameSpecifierNestingThreshold",
+                NameSpecifierNestingThreshold);
+}
+
+void StaticAccessedThroughInstanceCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      memberExpr(hasDeclaration(anyOf(cxxMethodDecl(isStaticStorageClass()),
+                                      varDecl(hasStaticStorageDuration()))),
+                 unless(isInTemplateInstantiation()))
+          .bind("memberExpression"),
+      this);
+}
+
+void StaticAccessedThroughInstanceCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *MemberExpression =
+      Result.Nodes.getNodeAs<MemberExpr>("memberExpression");
+
+  if (MemberExpression->getLocStart().isMacroID())
+    return;
+
+  const Expr *BaseExpr = MemberExpression->getBase();
+
+  // Do not warn for overlaoded -> operators.
+  if (isa<CXXOperatorCallExpr>(BaseExpr))
+    return;
+
+  QualType BaseType =
+      BaseExpr->getType()->isPointerType()
+          ? BaseExpr->getType()->getPointeeType().getUnqualifiedType()
+          : BaseExpr->getType().getUnqualifiedType();
+
+  const ASTContext *AstContext = Result.Context;
+  PrintingPolicy PrintingPolicyWithSupressedTag(AstContext->getLangOpts());
+  PrintingPolicyWithSupressedTag.SuppressTagKeyword = true;
+  std::string BaseTypeName =
+      BaseType.getAsString(PrintingPolicyWithSupressedTag);
+
+  SourceLocation MemberExprStartLoc = MemberExpression->getLocStart();
+  auto Diag =
+      diag(MemberExprStartLoc, "static member accessed through instance");
+
+  if (BaseExpr->HasSideEffects(*AstContext) ||
+      getNameSpecifierNestingLevel(BaseType) > NameSpecifierNestingThreshold)
+    return;
+
+  Diag << FixItHint::CreateReplacement(
+      CharSourceRange::getCharRange(MemberExprStartLoc,
+                                    MemberExpression->getMemberLoc()),
+      BaseTypeName + "::");
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang