llvm-project/clang-tools-extra/clang-tidy/misc/UnusedParametersCheck.cpp

113 lines
4.1 KiB
C++

//===--- UnusedParametersCheck.cpp - clang-tidy----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "UnusedParametersCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
void UnusedParametersCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(functionDecl().bind("function"), this);
}
static FixItHint removeParameter(const FunctionDecl *Function, unsigned Index) {
const ParmVarDecl *Param = Function->getParamDecl(Index);
unsigned ParamCount = Function->getNumParams();
SourceRange RemovalRange = Param->getSourceRange();
if (ParamCount == 1)
return FixItHint::CreateRemoval(RemovalRange);
if (Index == 0)
RemovalRange.setEnd(
Function->getParamDecl(Index + 1)->getLocStart().getLocWithOffset(-1));
else
RemovalRange.setBegin(
Function->getParamDecl(Index - 1)->getLocEnd().getLocWithOffset(1));
return FixItHint::CreateRemoval(RemovalRange);
}
static FixItHint removeArgument(const CallExpr *Call, unsigned Index) {
unsigned ArgCount = Call->getNumArgs();
const Expr *Arg = Call->getArg(Index);
SourceRange RemovalRange = Arg->getSourceRange();
if (ArgCount == 1)
return FixItHint::CreateRemoval(RemovalRange);
if (Index == 0)
RemovalRange.setEnd(
Call->getArg(Index + 1)->getLocStart().getLocWithOffset(-1));
else
RemovalRange.setBegin(
Call->getArg(Index - 1)->getLocEnd().getLocWithOffset(1));
return FixItHint::CreateRemoval(RemovalRange);
}
void UnusedParametersCheck::warnOnUnusedParameter(
const MatchFinder::MatchResult &Result, const FunctionDecl *Function,
unsigned ParamIndex) {
const auto *Param = Function->getParamDecl(ParamIndex);
auto MyDiag = diag(Param->getLocation(), "parameter '%0' is unused")
<< Param->getName();
auto UsedByRef = [&] {
return !ast_matchers::match(
decl(hasDescendant(
declRefExpr(to(equalsNode(Function)),
unless(hasAncestor(
callExpr(callee(equalsNode(Function)))))))),
*Result.Context->getTranslationUnitDecl(), *Result.Context)
.empty();
};
// Comment out parameter name for non-local functions.
if (Function->isExternallyVisible() ||
!Result.SourceManager->isInMainFile(Function->getLocation()) ||
UsedByRef()) {
SourceRange RemovalRange(Param->getLocation(), Param->getLocEnd());
// Note: We always add a space before the '/*' to not accidentally create a
// '*/*' for pointer types, which doesn't start a comment. clang-format will
// clean this up afterwards.
MyDiag << FixItHint::CreateReplacement(
RemovalRange, (Twine(" /*") + Param->getName() + "*/").str());
return;
}
// Fix all redeclarations.
for (const FunctionDecl *FD : Function->redecls())
MyDiag << removeParameter(FD, ParamIndex);
// Fix all call sites.
auto CallMatches = ast_matchers::match(
decl(forEachDescendant(
callExpr(callee(functionDecl(equalsNode(Function)))).bind("x"))),
*Result.Context->getTranslationUnitDecl(), *Result.Context);
for (const auto &Match : CallMatches)
MyDiag << removeArgument(Match.getNodeAs<CallExpr>("x"), ParamIndex);
}
void UnusedParametersCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("function");
if (!Function->doesThisDeclarationHaveABody())
return;
for (unsigned i = 0, e = Function->getNumParams(); i != e; ++i) {
const auto *Param = Function->getParamDecl(i);
if (Param->isUsed() || Param->isReferenced() || !Param->getDeclName() ||
Param->hasAttr<UnusedAttr>())
continue;
warnOnUnusedParameter(Result, Function, i);
}
}
} // namespace tidy
} // namespace clang