[clang-tools-extra] [clang-tidy] Add check performance-lost-std-move (PR #139525)
via cfe-commits
cfe-commits at lists.llvm.org
Sat May 31 22:04:48 PDT 2025
================
@@ -0,0 +1,180 @@
+//===--- LostStdMoveCheck.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 "LostStdMoveCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+template <typename Node>
+void extractNodesByIdTo(ArrayRef<BoundNodes> Matches, StringRef ID,
+ llvm::SmallPtrSet<const Node*, 16>& Nodes) {
+ for (const BoundNodes& Match : Matches)
+ Nodes.insert(Match.getNodeAs<Node>(ID));
+}
+
+static llvm::SmallPtrSet<const DeclRefExpr*, 16> allDeclRefExprsHonourLambda(
+ const VarDecl& VarDecl, const Decl& Decl, ASTContext& Context) {
+ auto Matches = match(
+ decl(forEachDescendant(
+ declRefExpr(to(varDecl(equalsNode(&VarDecl))),
+
+ unless(hasAncestor(lambdaExpr(hasAnyCapture(lambdaCapture(
+ capturesVar(varDecl(equalsNode(&VarDecl))))))))
+
+ )
+ .bind("declRef"))),
+ Decl, Context);
+ llvm::SmallPtrSet<const DeclRefExpr*, 16> DeclRefs;
+ extractNodesByIdTo(Matches, "declRef", DeclRefs);
+ return DeclRefs;
+}
+
+static const Expr* getLastVarUsage(const VarDecl& Var, const Decl& Func,
+ ASTContext& Context) {
+ auto Exprs = allDeclRefExprsHonourLambda(Var, Func, Context);
+
+ const Expr* LastExpr = nullptr;
+ for (const clang::DeclRefExpr* Expr : Exprs) {
+ if (!LastExpr) LastExpr = Expr;
+
+ if (LastExpr->getBeginLoc() < Expr->getBeginLoc()) LastExpr = Expr;
+ }
+
+ return LastExpr;
+}
+
+AST_MATCHER(CXXRecordDecl, hasTrivialMoveConstructor) {
+ return Node.hasDefinition() && Node.hasTrivialMoveConstructor();
+}
+
+void LostStdMoveCheck::registerMatchers(MatchFinder* Finder) {
+ auto ReturnParent =
+ hasParent(expr(hasParent(cxxConstructExpr(hasParent(returnStmt())))));
+
+ auto OutermostExpr = expr(unless(hasParent(expr())));
+ auto LeafStatement = stmt(OutermostExpr);
+
+ Finder->addMatcher(
+ declRefExpr(
+ // not "return x;"
+ unless(ReturnParent),
+
+ unless(hasType(namedDecl(hasName("::std::string_view")))),
+
+ // non-trivial type
+ hasType(hasCanonicalType(hasDeclaration(cxxRecordDecl()))),
+
+ // non-trivial X(X&&)
+ unless(hasType(hasCanonicalType(
+ hasDeclaration(cxxRecordDecl(hasTrivialMoveConstructor()))))),
+
+ // Not in a cycle
+ unless(hasAncestor(forStmt())),
+
+ unless(hasAncestor(doStmt())),
+
+ unless(hasAncestor(whileStmt())),
+
+ // Not in a body of lambda
+ unless(hasAncestor(compoundStmt(hasAncestor(lambdaExpr())))),
+
+ // only non-X&
+ unless(hasDeclaration(
+ varDecl(hasType(qualType(lValueReferenceType()))))),
+
+ hasAncestor(LeafStatement.bind("leaf_statement")),
+
+ hasDeclaration(
+ varDecl(hasAncestor(functionDecl().bind("func"))).bind("decl")),
+
+ anyOf(
+
+ // f(x)
+ hasParent(expr(hasParent(cxxConstructExpr())).bind("use_parent")),
+
+ // f((x))
+ hasParent(parenExpr(hasParent(
+ expr(hasParent(cxxConstructExpr())).bind("use_parent"))))
+
+ )
+
+ )
+ .bind("use"),
+ this);
+}
+
+void LostStdMoveCheck::check(const MatchFinder::MatchResult& Result) {
+ const auto* MatchedDecl = Result.Nodes.getNodeAs<VarDecl>("decl");
+ const auto* MatchedFunc = Result.Nodes.getNodeAs<FunctionDecl>("func");
+ const auto* MatchedUse = Result.Nodes.getNodeAs<Expr>("use");
+ const auto* MatchedUseCall = Result.Nodes.getNodeAs<CallExpr>("use_parent");
+ const auto* MatchedLeafStatement =
+ Result.Nodes.getNodeAs<Stmt>("leaf_statement");
+
+ if (!MatchedDecl->hasLocalStorage()) return;
----------------
EugeneZelenko wrote:
Should be two lines as next statement.
https://github.com/llvm/llvm-project/pull/139525
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