[clang-tools-extra] [clang-tidy] Add modernize-use-shared-ptr-array check (#180441) (PR #199458)

[Yanzuo Liu via cfe-commits]

================
@@ -0,0 +1,378 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "UseSharedPtrArrayCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/TypeLoc.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+AST_MATCHER(FunctionDecl, funcHasSingleArrayDeleteBody) {
+  if (Node.getNumParams() != 1 || !Node.hasBody())
+    return false;
+  const ParmVarDecl *Param = Node.getParamDecl(0);
+  const auto *CS = dyn_cast<CompoundStmt>(Node.getBody());
+  if (!CS || CS->size() != 1)
+    return false;
+  const auto *E = dyn_cast<Expr>(CS->body_front());
+  if (!E)
+    return false;
+  const auto *DE = dyn_cast<CXXDeleteExpr>(E->IgnoreParenImpCasts());
+  if (!DE || !DE->isArrayForm())
+    return false;
+  const auto *DRE =
+      dyn_cast<DeclRefExpr>(DE->getArgument()->IgnoreParenImpCasts());
+  return DRE && DRE->getDecl() == Param;
+}
+
+AST_MATCHER(LambdaExpr, lambdaHasSingleArrayDeleteBody) {
+  if (Node.capture_size() != 0)
+    return false;
+  const CXXMethodDecl *CallOp = Node.getCallOperator();
+  if (!CallOp || CallOp->getNumParams() != 1)
+    return false;
+  const ParmVarDecl *Param = CallOp->getParamDecl(0);
+  const auto *CS = dyn_cast<CompoundStmt>(Node.getBody());
+  if (!CS || CS->size() != 1)
+    return false;
+  const auto *E = dyn_cast<Expr>(CS->body_front());
+  if (!E)
+    return false;
+  const auto *DE = dyn_cast<CXXDeleteExpr>(E->IgnoreParenImpCasts());
+  if (!DE || !DE->isArrayForm())
+    return false;
+  const auto *DRE =
+      dyn_cast<DeclRefExpr>(DE->getArgument()->IgnoreParenImpCasts());
+  return DRE && DRE->getDecl() == Param;
+}
+
+void UseSharedPtrArrayCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      cxxConstructExpr(
+          unless(isInTemplateInstantiation()),
+          hasType(qualType(hasDeclaration(classTemplateSpecializationDecl(
+              hasName("::std::shared_ptr"), templateArgumentCountIs(1))))),
+
+          argumentCountIs(2),
+
+          hasArgument(
+              0, ignoringParenImpCasts(cxxNewExpr(isArray()).bind("newExpr"))),
+
+          hasArgument(
+              1, ignoringImplicit(anyOf(
+
+                     cxxConstructExpr(
+                         hasType(qualType(hasCanonicalType(
+                             hasDeclaration(classTemplateSpecializationDecl(
+                                 hasName("::std::default_delete")))))))
+                         .bind("defaultDelete"),
+
+                     lambdaExpr(lambdaHasSingleArrayDeleteBody())
+                         .bind("lambdaDeleter"),
+
+                     declRefExpr(to(functionDecl(funcHasSingleArrayDeleteBody())
+                                        .bind("deleterFunction")))))))
+
+          .bind("sharedPtrCtor"),
+      this);
+}
+
+// From bugprone-smart-ptr-array-mismatch-check
+// Same as SmartPtrArrayMismatchCheck::getConstructedVarOrField.
+static const DeclaratorDecl *
+getConstructedVarOrField(const Expr *FoundConstructExpr, ASTContext &Ctx) {
+  const DynTypedNodeList ConstructParents =
+      Ctx.getParentMapContext().getParents(*FoundConstructExpr);
+  if (ConstructParents.size() != 1)
+    return nullptr;
+  const auto *ParentDecl = ConstructParents.begin()->get<DeclaratorDecl>();
+  if (isa_and_nonnull<VarDecl, FieldDecl>(ParentDecl))
+    return ParentDecl;
+
+  return nullptr;
+}
+
+// Returns a StringRef into the SourceManager-owned buffer; stable for lifetime
+// of the ASTContext.
+static StringRef extractWrittenElementType(const TypeSourceInfo *TSI,
+                                           SourceManager &SM,
+                                           const LangOptions &LO) {
+  if (!TSI)
+    return {};
+  const TypeLoc TL = TSI->getTypeLoc().getUnqualifiedLoc();
+  auto TSTypeLoc = TL.getAsAdjusted<TemplateSpecializationTypeLoc>();
+  if (!TSTypeLoc || TSTypeLoc.getNumArgs() < 1)
+    return {};
+  const TypeSourceInfo *ArgTSI = TSTypeLoc.getArgLoc(0).getTypeSourceInfo();
+  if (!ArgTSI)
+    return {};
+  const TypeLoc ArgTL = ArgTSI->getTypeLoc();
+  const CharSourceRange R =
+      CharSourceRange::getTokenRange(ArgTL.getBeginLoc(), ArgTL.getEndLoc());
+  return Lexer::getSourceText(R, SM, LO);
+}
+
+static QualType getDeleterParamPointee(const Expr *DeleterArg) {
+  const Expr *E = DeleterArg->IgnoreParenImpCasts();
+
+  if (const auto *L = dyn_cast<LambdaExpr>(E)) {
+    const CXXMethodDecl *CallOp = L->getCallOperator();
+    if (!CallOp || CallOp->getNumParams() != 1)
+      return {};
+    const QualType P = CallOp->getParamDecl(0)->getType();
+    if (!P->isPointerType())
+      return {};
+    return P->getPointeeType();
+  }
+
+  if (const auto *DRE = dyn_cast<DeclRefExpr>(E)) {
+    if (const auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
+      if (FD->getNumParams() != 1)
+        return {};
+      const QualType P = FD->getParamDecl(0)->getType();
+      if (!P->isPointerType())
+        return {};
+      return P->getPointeeType();
+    }
+  }
+
+  // default_delete<T[]>: the template argument is T[], extract T.
+  if (const auto *CE = dyn_cast<CXXConstructExpr>(E)) {
+    const auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(
+        CE->getConstructor()->getParent());
+    if (!CTSD || CTSD->getTemplateArgs().size() != 1)
+      return {};
+    const TemplateArgument &Arg = CTSD->getTemplateArgs()[0];
+    if (Arg.getKind() != TemplateArgument::Type)
+      return {};
+    const QualType T = Arg.getAsType();
+    if (!T->isArrayType())
+      return {};
+    return cast<ArrayType>(T.getTypePtr())->getElementType();
+  }
+
+  return {};
+}
+
+// Manual parent walk rather than a matcher because implicit
+// wrappers obscure assignment contexts.
+static bool isInsideAssignment(ASTContext &Ctx, const CXXConstructExpr *Ctor) {
+  DynTypedNode Node = DynTypedNode::create(*Ctor);
+  while (true) {
+    auto Parents = Ctx.getParents(Node);
+    if (Parents.empty())
+      return false;
+
+    bool Advanced = false;
+    for (const DynTypedNode &P : Parents) {
+      if (const auto *Op = P.get<CXXOperatorCallExpr>();
+          Op && Op->getOperator() == OO_Equal)
+        return true;
+
+      // VarDecl indicates initialization rather than assignment.
+      if (P.get<VarDecl>())
+        return false;
+
+      if (!Advanced && (P.get<Expr>() || P.get<CXXBindTemporaryExpr>() ||
+                        P.get<MaterializeTemporaryExpr>())) {
+        Node = P;
+        Advanced = true;
+      }
+    }
+
+    if (!Advanced)
+      return false;
+  }
+}
+
+// FixIt 2: remove ", deleter" — from the end of arg 0 to the end of arg 1.
+static std::optional<FixItHint>
+buildRemoveDeleterFix(const CXXConstructExpr *Ctor, SourceManager &SM,
+                      const LangOptions &LO) {
+  const Expr *Arg0 = Ctor->getArg(0);
+  const Expr *Arg1 = Ctor->getArg(1);
+
+  const SourceLocation Arg0End =
+      Lexer::getLocForEndOfToken(Arg0->getEndLoc(), 0, SM, LO);
+  const SourceLocation Arg1End =
+      Lexer::getLocForEndOfToken(Arg1->getEndLoc(), 0, SM, LO);
+
+  if (Arg0End.isInvalid() || Arg1End.isInvalid())
+    return std::nullopt;
+
+  return FixItHint::CreateRemoval(
+      CharSourceRange::getCharRange(Arg0End, Arg1End));
+}
+
+void UseSharedPtrArrayCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructExpr>("sharedPtrCtor");
+  assert(Ctor && "sharedPtrCtor must be bound");
+
+  const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>("newExpr");
+  assert(NewExpr && "newExpr must be bound");
+
+  const auto *CTSD = cast<ClassTemplateSpecializationDecl>(
+      Ctor->getType()->getAsCXXRecordDecl());
+  assert(CTSD->getTemplateArgs().size() == 1 &&
+         "shared_ptr must have exactly one template argument");
+
+  const TemplateArgument &TyArg = CTSD->getTemplateArgs()[0];
+  assert(TyArg.getKind() == TemplateArgument::Type &&
+         "shared_ptr template argument must be a type");
+
+  QualType ElemTy = TyArg.getAsType();
+  if (ElemTy->isArrayType() || ElemTy->isDependentType())
----------------
zwuis wrote:

Use `hasTemplateArgument`/`hasTemplateArgumentLoc` matcher so that we can filter element types in AST matchers.

https://github.com/llvm/llvm-project/pull/199458