================ @@ -0,0 +1,217 @@ +//===--- StringViewSubstrCheck.cpp - clang-tidy------------------*- C++ -*-===// +// +// 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 "StringViewSubstrCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" +#include "clang/Lex/Lexer.h" + +using namespace clang::ast_matchers; + +namespace clang::tidy::readability { + +void StringViewSubstrCheck::registerMatchers(MatchFinder *Finder) { + // Match string_view type + const auto StringViewDecl = recordDecl(hasName("::std::basic_string_view")); + const auto IsStringView = qualType( + hasUnqualifiedDesugaredType(recordType(hasDeclaration(StringViewDecl)))); + + // Match substr() call on string_views + const auto SubstrCall = cxxMemberCallExpr( + callee(memberExpr(hasDeclaration(cxxMethodDecl(hasName("substr"))))), + on(expr(hasType(IsStringView)).bind("source"))); + + // Match assignment to string_view's substr, but exclude assignments in + // expressions + Finder->addMatcher( + stmt(cxxOperatorCallExpr( + unless(isInTemplateInstantiation()), + hasOverloadedOperatorName("="), + hasArgument(0, expr(hasType(IsStringView)).bind("target")), + hasArgument(1, SubstrCall.bind("substr_call"))) + .bind("assignment"), + // Exclude assignments used in larger expressions + unless(hasAncestor(varDecl())), unless(hasAncestor(callExpr()))), + this); +} + +void StringViewSubstrCheck::check(const MatchFinder::MatchResult &Result) { + const auto *Assignment = + Result.Nodes.getNodeAs<CXXOperatorCallExpr>("assignment"); + const auto *Target = Result.Nodes.getNodeAs<Expr>("target"); + const auto *Source = Result.Nodes.getNodeAs<Expr>("source"); + const auto *SubstrCall = + Result.Nodes.getNodeAs<CXXMemberCallExpr>("substr_call"); + + if (!Assignment || !Target || !Source || !SubstrCall) { + return; + } + + // Get the DeclRefExpr for the target and source + const auto *TargetDRE = dyn_cast<DeclRefExpr>(Target->IgnoreParenImpCasts()); + const auto *SourceDRE = dyn_cast<DeclRefExpr>(Source->IgnoreParenImpCasts()); + + if (!TargetDRE || !SourceDRE) { + return; + } + + const Expr *StartArg = SubstrCall->getArg(0); + const Expr *LengthArg = + SubstrCall->getNumArgs() > 1 ? SubstrCall->getArg(1) : nullptr; + + std::string StartText = + Lexer::getSourceText( + CharSourceRange::getTokenRange(StartArg->getSourceRange()), + *Result.SourceManager, Result.Context->getLangOpts()) + .str(); + + const bool IsSameVar = (TargetDRE->getDecl() == SourceDRE->getDecl()); + + // Case 1: Check for remove_prefix pattern + if (!LengthArg || isa<CXXDefaultArgExpr>(LengthArg)) { + if (IsSameVar) { + std::string Replacement = TargetDRE->getNameInfo().getAsString() + + ".remove_prefix(" + StartText + ")"; + diag(Assignment->getBeginLoc(), "prefer 'remove_prefix' over 'substr' " + "for removing characters from the start") + << FixItHint::CreateReplacement(Assignment->getSourceRange(), + Replacement); + } + return; + } + + // Check if StartArg resolves to 0 + bool IsZero = false; + + // Handle cases where StartArg is an integer literal + if (const auto *IL = + dyn_cast<IntegerLiteral>(StartArg->IgnoreParenImpCasts())) { + IsZero = IL->getValue() == 0; + } + + // Optional: Handle cases where StartArg evaluates to zero + if (!IsZero) { + // Add logic for other constant evaluation (e.g., constexpr evaluation) + const auto &EvalResult = StartArg->EvaluateKnownConstInt(*Result.Context); + IsZero = !EvalResult.isNegative() && EvalResult == 0; + } + + // If StartArg resolves to 0, handle the case + if (IsZero) { + bool isFullCopy = false; ---------------- 5chmidti wrote:
nit: `IsFullCopy` https://github.com/llvm/llvm-project/pull/120055 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
