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//===--- 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(
parmVarDecl(hasAncestor(functionDecl().bind("function"))).bind("x"),
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::check(const MatchFinder::MatchResult &Result) {
const auto *Function = Result.Nodes.getNodeAs<FunctionDecl>("function");
if (!Function->doesThisDeclarationHaveABody())
return;
const auto *Param = Result.Nodes.getNodeAs<ParmVarDecl>("x");
if (Param->isUsed())
return;
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() &&
Function->getStorageClass() != StorageClass::SC_Static) ||
UsedByRef()) {
SourceRange RemovalRange(Param->getLocation(), Param->getLocEnd());
MyDiag << FixItHint::CreateReplacement(
RemovalRange, (Twine(" /*") + Param->getName() + "*/").str());
return;
}
// Handle local functions by deleting the parameters.
unsigned ParamIndex = Param->getFunctionScopeIndex();
// 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);
}
} // namespace tidy
} // namespace clang
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