forked from OSchip/llvm-project
140 lines
4.8 KiB
C++
140 lines
4.8 KiB
C++
//===--- RedundantStrcatCallsCheck.cpp - clang-tidy------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "RedundantStrcatCallsCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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using namespace clang::ast_matchers;
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namespace clang {
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namespace tidy {
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namespace abseil {
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// TODO: Features to add to the check:
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// - Make it work if num_args > 26.
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// - Remove empty literal string arguments.
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// - Collapse consecutive literal string arguments into one (remove the ,).
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// - Replace StrCat(a + b) -> StrCat(a, b) if a or b are strings.
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// - Make it work in macros if the outer and inner StrCats are both in the
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// argument.
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void RedundantStrcatCallsCheck::registerMatchers(MatchFinder* Finder) {
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const auto CallToStrcat =
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callExpr(callee(functionDecl(hasName("::absl::StrCat"))));
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const auto CallToStrappend =
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callExpr(callee(functionDecl(hasName("::absl::StrAppend"))));
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// Do not match StrCat() calls that are descendants of other StrCat calls.
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// Those are handled on the ancestor call.
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const auto CallToEither = callExpr(
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callee(functionDecl(hasAnyName("::absl::StrCat", "::absl::StrAppend"))));
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Finder->addMatcher(
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callExpr(CallToStrcat, unless(hasAncestor(CallToEither))).bind("StrCat"),
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this);
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Finder->addMatcher(CallToStrappend.bind("StrAppend"), this);
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}
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namespace {
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struct StrCatCheckResult {
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int NumCalls = 0;
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std::vector<FixItHint> Hints;
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};
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void removeCallLeaveArgs(const CallExpr *Call, StrCatCheckResult *CheckResult) {
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if (Call->getNumArgs() == 0)
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return;
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// Remove 'Foo('
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CheckResult->Hints.push_back(
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FixItHint::CreateRemoval(CharSourceRange::getCharRange(
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Call->getBeginLoc(), Call->getArg(0)->getBeginLoc())));
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// Remove the ')'
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CheckResult->Hints.push_back(
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FixItHint::CreateRemoval(CharSourceRange::getCharRange(
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Call->getRParenLoc(), Call->getEndLoc().getLocWithOffset(1))));
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}
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const clang::CallExpr *processArgument(const Expr *Arg,
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const MatchFinder::MatchResult &Result,
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StrCatCheckResult *CheckResult) {
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const auto IsAlphanum = hasDeclaration(cxxMethodDecl(hasName("AlphaNum")));
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static const auto* const Strcat = new auto(hasName("::absl::StrCat"));
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const auto IsStrcat = cxxBindTemporaryExpr(
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has(callExpr(callee(functionDecl(*Strcat))).bind("StrCat")));
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if (const auto *SubStrcatCall = selectFirst<const CallExpr>(
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"StrCat",
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match(stmt(traverse(TK_AsIs,
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anyOf(cxxConstructExpr(IsAlphanum,
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hasArgument(0, IsStrcat)),
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IsStrcat))),
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*Arg->IgnoreParenImpCasts(), *Result.Context))) {
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removeCallLeaveArgs(SubStrcatCall, CheckResult);
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return SubStrcatCall;
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}
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return nullptr;
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}
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StrCatCheckResult processCall(const CallExpr *RootCall, bool IsAppend,
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const MatchFinder::MatchResult &Result) {
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StrCatCheckResult CheckResult;
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std::deque<const CallExpr*> CallsToProcess = {RootCall};
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while (!CallsToProcess.empty()) {
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++CheckResult.NumCalls;
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const CallExpr* CallExpr = CallsToProcess.front();
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CallsToProcess.pop_front();
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int StartArg = CallExpr == RootCall && IsAppend;
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for (const auto *Arg : CallExpr->arguments()) {
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if (StartArg-- > 0)
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continue;
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if (const clang::CallExpr *Sub =
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processArgument(Arg, Result, &CheckResult)) {
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CallsToProcess.push_back(Sub);
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}
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}
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}
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return CheckResult;
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}
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} // namespace
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void RedundantStrcatCallsCheck::check(const MatchFinder::MatchResult& Result) {
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bool IsAppend;
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const CallExpr* RootCall;
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if ((RootCall = Result.Nodes.getNodeAs<CallExpr>("StrCat")))
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IsAppend = false;
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else if ((RootCall = Result.Nodes.getNodeAs<CallExpr>("StrAppend")))
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IsAppend = true;
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else
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return;
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if (RootCall->getBeginLoc().isMacroID()) {
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// Ignore calls within macros.
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// In many cases the outer StrCat part of the macro and the inner StrCat is
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// a macro argument. Removing the inner StrCat() converts one macro
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// argument into many.
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return;
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}
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const StrCatCheckResult CheckResult = processCall(RootCall, IsAppend, Result);
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if (CheckResult.NumCalls == 1) {
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// Just one call, so nothing to fix.
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return;
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}
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diag(RootCall->getBeginLoc(),
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"multiple calls to 'absl::StrCat' can be flattened into a single call")
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<< CheckResult.Hints;
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}
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} // namespace abseil
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} // namespace tidy
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} // namespace clang
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