[clang-tools-extra] [clang-tidy] Add bugprone-move-shared-pointer-contents check. (PR #67467)

[via cfe-commits]

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+//===--- MoveSharedPointerContentsCheck.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 "MoveSharedPointerContentsCheck.h"
+#include "../ClangTidyCheck.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+namespace {
+
+// Reports whether the QualType matches the inner matcher, which is expected to be
+// matchesAnyListedName. The QualType is expected to either point to a RecordDecl
+// (for concrete types) or an ElaboratedType (for dependent ones).
+AST_MATCHER_P(QualType, isSharedPointer,
+              clang::ast_matchers::internal::Matcher<NamedDecl>, InnerMatcher) {
+  if (const auto *RD = Node.getTypePtr()->getAsCXXRecordDecl(); RD != nullptr) {
+    return InnerMatcher.matches(*RD, Finder, Builder);
+  } else if (const auto *ED = Node.getTypePtr()->getAs<ElaboratedType>();
+             ED != nullptr) {
+    if (const auto *TS = ED->getNamedType()
+                             .getTypePtr()
+                             ->getAs<TemplateSpecializationType>();
+        TS != nullptr) {
+      return InnerMatcher.matches(*TS->getTemplateName().getAsTemplateDecl(),
+                                  Finder, Builder);
+    }
+  }
+
+  return false;
+}
+
+} // namespace
+
+MoveSharedPointerContentsCheck::MoveSharedPointerContentsCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      SharedPointerClasses(utils::options::parseStringList(
+          Options.get("SharedPointerClasses", "::std::shared_ptr;::boost::shared_pointer"))) {}
+
+void MoveSharedPointerContentsCheck::registerMatchers(MatchFinder *Finder) {
+  auto isStdMove = callee(functionDecl(hasAnyName("::std::move", "::std::forward")));
+
+  auto resolvedType = callExpr(anyOf(
+      // Resolved type, direct move.
+      callExpr(
+          isStdMove,
+          hasArgument(
+              0,
+              cxxOperatorCallExpr(
+                  hasOverloadedOperatorName("*"),
+                  hasDescendant(declRefExpr(hasType(qualType(isSharedPointer(
----------------
pizzud wrote:

Doing that gives me a QualType for the underlying type, not the user-visible type. As an example, this matters when operator* or get() are declared in a parent rather than the visible class, which is the case for at least one major implementation of std::shared_ptr (I think it's libstdc++ but haven't looked in several months) and is visible in the unit tests because the dummy implementation in use has a std::__shared_ptr that defines them and std::shared_ptr inherits from it. Using DeclRefExpr is an intentional attempt to get at the user-visible type of the variable. The hasDescendant can at least be hasArgument(0).

The good news is that I added your example to the unit tests and it doesn't actually trigger.

https://github.com/llvm/llvm-project/pull/67467