[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 {
+
+MoveSharedPointerContentsCheck::MoveSharedPointerContentsCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      SharedPointerClasses(utils::options::parseStringList(
+          Options.get("SharedPointerClasses", "::std::shared_ptr"))) {}
+
+void MoveSharedPointerContentsCheck::registerMatchers(MatchFinder *Finder) {
+  auto isStdMove = callee(functionDecl(hasName("::std::move")));
+
+  // Resolved type, direct move.
+  Finder->addMatcher(
+      callExpr(isStdMove, hasArgument(0, cxxOperatorCallExpr(
+                                             hasOverloadedOperatorName("*"),
+                                             callee(cxxMethodDecl(ofClass(
+                                                 matchers::matchesAnyListedName(
+                                                     SharedPointerClasses)))))))
+          .bind("call"),
+      this);
+
+  // Resolved type, move out of get().
+  Finder->addMatcher(
+      callExpr(
+          isStdMove,
+          hasArgument(
+              0, unaryOperator(
+                     hasOperatorName("*"),
+                     hasUnaryOperand(cxxMemberCallExpr(callee(cxxMethodDecl(
+                         hasName("get"), ofClass(matchers::matchesAnyListedName(
+                                             SharedPointerClasses)))))))))
+          .bind("get_call"),
+      this);
+
+  auto isStdMoveUnresolved = callee(unresolvedLookupExpr(
+      hasAnyDeclaration(namedDecl(hasUnderlyingDecl(hasName("::std::move"))))));
+
+  // Unresolved type, direct move.
+  Finder->addMatcher(
+      callExpr(
+          isStdMoveUnresolved,
+          hasArgument(0, unaryOperator(hasOperatorName("*"),
+                                       hasUnaryOperand(declRefExpr(hasType(
+                                           qualType().bind("unresolved_p")))))))
+          .bind("unresolved_call"),
+      this);
+  // Annoyingly, the declRefExpr in the unresolved-move-of-get() case
+  // is of <dependent type> rather than shared_ptr<T>, so we have to
+  // just fetch the variable. This does leave a gap where a temporary
+  // shared_ptr wouldn't be caught, but moving out of a temporary
+  // shared pointer is a truly wild thing to do so it should be okay.
+
+  // Unresolved type, move out of get().
+  Finder->addMatcher(
+      callExpr(isStdMoveUnresolved,
+               hasArgument(
+                   0, unaryOperator(hasOperatorName("*"),
+                                    hasDescendant(cxxDependentScopeMemberExpr(
+                                        hasMemberName("get"))),
+                                    hasDescendant(declRefExpr(to(
+                                        varDecl().bind("unresolved_get_p")))))))
+          .bind("unresolved_get_call"),
+      this);
+}
+
+bool MoveSharedPointerContentsCheck::isSharedPointerClass(
+    const VarDecl *VD) const {
+  if (VD == nullptr) {
+    return false;
+  }
+
+  const QualType QT = VD->getType();
+  return isSharedPointerClass(&QT);
+}
+
+bool MoveSharedPointerContentsCheck::isSharedPointerClass(
+    const QualType *QT) const {
+  if (QT == nullptr) {
+    return false;
+  }
+  // We want the qualified name without template parameters,
+  // const/volatile, or reference/pointer qualifiers so we can look
+  // it up in SharedPointerClasses. This is a bit messy, but gets us
+  // to the underlying type without template parameters (eg
+  // std::shared_ptr) or const/volatile qualifiers even in the face of
+  // typedefs.
+
+  bool found = false;
+  const auto *Template = llvm::dyn_cast<TemplateSpecializationType>(
+      QT->getSplitDesugaredType().Ty);
+  if (Template != nullptr) {
+    const std::string TypeName = Template->getTemplateName()
+                                     .getAsTemplateDecl()
+                                     ->getQualifiedNameAsString();
+    for (const llvm::StringRef SharedPointer : SharedPointerClasses) {
+      // SharedPointer entries may or may not have leading ::, but TypeName
+      // definitely won't.
+      if (SharedPointer == TypeName || SharedPointer.substr(2) == TypeName) {
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pizzud wrote:

Thanks for the pointer, I finally managed to figure this out.

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