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//===--- UseUsingCheck.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 "UseUsingCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace modernize {
UseUsingCheck::UseUsingCheck(StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
void UseUsingCheck::registerMatchers(MatchFinder *Finder) {
if (!getLangOpts().CPlusPlus11)
return;
Finder->addMatcher(typedefDecl(unless(isInstantiated())).bind("typedef"),
this);
}
// Checks if 'typedef' keyword can be removed - we do it only if
// it is the only declaration in a declaration chain.
static bool CheckRemoval(SourceManager &SM, SourceLocation StartLoc,
ASTContext &Context) {
assert(StartLoc.isFileID() && "StartLoc must not be in a macro");
std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(StartLoc);
StringRef File = SM.getBufferData(LocInfo.first);
const char *TokenBegin = File.data() + LocInfo.second;
Lexer DeclLexer(SM.getLocForStartOfFile(LocInfo.first), Context.getLangOpts(),
File.begin(), TokenBegin, File.end());
Token Tok;
int NestingLevel = 0; // Parens, braces, and square brackets
int AngleBracketLevel = 0;
bool FoundTypedef = false;
while (!DeclLexer.LexFromRawLexer(Tok) && !Tok.is(tok::semi)) {
switch (Tok.getKind()) {
case tok::l_brace:
if (NestingLevel == 0 && AngleBracketLevel == 0) {
// At top level, this might be the `typedef struct {...} T;` case.
// Inside parens, square brackets, or angle brackets it's not.
return false;
}
++NestingLevel;
break;
case tok::l_paren:
case tok::l_square:
++NestingLevel;
break;
case tok::r_brace:
case tok::r_paren:
case tok::r_square:
--NestingLevel;
break;
case tok::less:
// If not nested in paren/brace/square bracket, treat as opening angle bracket.
if (NestingLevel == 0)
++AngleBracketLevel;
break;
case tok::greater:
// Per C++ 17 Draft N4659, Section 17.2/3
// https://timsong-cpp.github.io/cppwp/n4659/temp.names#3:
// "When parsing a template-argument-list, the first non-nested > is
// taken as the ending delimiter rather than a greater-than operator."
// If not nested in paren/brace/square bracket, treat as closing angle bracket.
if (NestingLevel == 0)
--AngleBracketLevel;
break;
case tok::comma:
if (NestingLevel == 0 && AngleBracketLevel == 0) {
// If there is a non-nested comma we have two or more declarations in this chain.
return false;
}
break;
case tok::raw_identifier:
if (Tok.getRawIdentifier() == "typedef") {
FoundTypedef = true;
}
break;
default:
break;
}
}
// Sanity check against weird macro cases.
return FoundTypedef;
}
void UseUsingCheck::check(const MatchFinder::MatchResult &Result) {
const auto *MatchedDecl = Result.Nodes.getNodeAs<TypedefDecl>("typedef");
if (MatchedDecl->getLocation().isInvalid())
return;
auto &Context = *Result.Context;
auto &SM = *Result.SourceManager;
SourceLocation StartLoc = MatchedDecl->getBeginLoc();
if (StartLoc.isMacroID() && IgnoreMacros)
return;
auto Diag = diag(StartLoc, "use 'using' instead of 'typedef'");
// do not fix if there is macro or array
if (MatchedDecl->getUnderlyingType()->isArrayType() || StartLoc.isMacroID())
return;
if (CheckRemoval(SM, StartLoc, Context)) {
auto printPolicy = PrintingPolicy(getLangOpts());
printPolicy.SuppressScope = true;
printPolicy.ConstantArraySizeAsWritten = true;
printPolicy.UseVoidForZeroParams = false;
Diag << FixItHint::CreateReplacement(
MatchedDecl->getSourceRange(),
"using " + MatchedDecl->getNameAsString() + " = " +
MatchedDecl->getUnderlyingType().getAsString(printPolicy));
}
}
} // namespace modernize
} // namespace tidy
} // namespace clang
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