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//===-- clang-tools-extra/clang-tidy/NoLintDirectiveHandler.cpp -----------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file This file implements the NoLintDirectiveHandler class, which is used
/// to locate NOLINT comments in the file being analyzed, to decide whether a
/// diagnostic should be suppressed.
///
//===----------------------------------------------------------------------===//
#include "NoLintDirectiveHandler.h"
#include "GlobList.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Tooling/Core/Diagnostic.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSwitch.h"
#include <cassert>
#include <cstddef>
#include <iterator>
#include <optional>
#include <string>
#include <tuple>
#include <type_traits>
#include <utility>
namespace clang::tidy {
//===----------------------------------------------------------------------===//
// NoLintType
//===----------------------------------------------------------------------===//
// The type - one of NOLINT[NEXTLINE/BEGIN/END].
enum class NoLintType { NoLint, NoLintNextLine, NoLintBegin, NoLintEnd };
// Convert a string like "NOLINTNEXTLINE" to its enum `Type::NoLintNextLine`.
// Return `std::nullopt` if the string is unrecognized.
static std::optional<NoLintType> strToNoLintType(StringRef Str) {
auto Type = llvm::StringSwitch<std::optional<NoLintType>>(Str)
.Case("NOLINT", NoLintType::NoLint)
.Case("NOLINTNEXTLINE", NoLintType::NoLintNextLine)
.Case("NOLINTBEGIN", NoLintType::NoLintBegin)
.Case("NOLINTEND", NoLintType::NoLintEnd)
.Default(std::nullopt);
return Type;
}
//===----------------------------------------------------------------------===//
// NoLintToken
//===----------------------------------------------------------------------===//
// Whitespace within a NOLINT's check list shall be ignored.
// "NOLINT( check1, check2 )" is equivalent to "NOLINT(check1,check2)".
// Return the check list with all extraneous whitespace removed.
static std::string trimWhitespace(StringRef Checks) {
SmallVector<StringRef> Split;
Checks.split(Split, ',');
for (StringRef &Check : Split)
Check = Check.trim();
return llvm::join(Split, ",");
}
namespace {
// Record the presence of a NOLINT comment - its type, location, checks -
// as parsed from the file's character contents.
class NoLintToken {
public:
// \param Checks:
// - If unspecified (i.e. `None`) then ALL checks are suppressed - equivalent
// to NOLINT(*).
// - An empty string means nothing is suppressed - equivalent to NOLINT().
// - Negative globs ignored (which would effectively disable the suppression).
NoLintToken(NoLintType Type, size_t Pos,
const std::optional<std::string> &Checks)
: Type(Type), Pos(Pos), ChecksGlob(std::make_unique<CachedGlobList>(
Checks.value_or("*"),
/*KeepNegativeGlobs=*/false)) {
if (Checks)
this->Checks = trimWhitespace(*Checks);
}
// The type - one of NOLINT[NEXTLINE/BEGIN/END].
NoLintType Type;
// The location of the first character, "N", in "NOLINT".
size_t Pos;
// If this NOLINT specifies checks, return the checks.
std::optional<std::string> checks() const { return Checks; }
// Whether this NOLINT applies to the provided check.
bool suppresses(StringRef Check) const { return ChecksGlob->contains(Check); }
private:
std::optional<std::string> Checks;
std::unique_ptr<CachedGlobList> ChecksGlob;
};
} // namespace
// Consume the entire buffer and return all `NoLintToken`s that were found.
static SmallVector<NoLintToken> getNoLints(StringRef Buffer) {
static constexpr llvm::StringLiteral NOLINT = "NOLINT";
SmallVector<NoLintToken> NoLints;
size_t Pos = 0;
while (Pos < Buffer.size()) {
// Find NOLINT:
const size_t NoLintPos = Buffer.find(NOLINT, Pos);
if (NoLintPos == StringRef::npos)
break; // Buffer exhausted
// Read [A-Z] characters immediately after "NOLINT", e.g. the "NEXTLINE" in
// "NOLINTNEXTLINE".
Pos = NoLintPos + NOLINT.size();
while (Pos < Buffer.size() && llvm::isAlpha(Buffer[Pos]))
++Pos;
// Is this a recognized NOLINT type?
const std::optional<NoLintType> NoLintType =
strToNoLintType(Buffer.slice(NoLintPos, Pos));
if (!NoLintType)
continue;
// Get checks, if specified.
std::optional<std::string> Checks;
if (Pos < Buffer.size() && Buffer[Pos] == '(') {
size_t ClosingBracket = Buffer.find_first_of("\n)", ++Pos);
if (ClosingBracket != StringRef::npos && Buffer[ClosingBracket] == ')') {
Checks = Buffer.slice(Pos, ClosingBracket).str();
Pos = ClosingBracket + 1;
}
}
NoLints.emplace_back(*NoLintType, NoLintPos, Checks);
}
return NoLints;
}
//===----------------------------------------------------------------------===//
// NoLintBlockToken
//===----------------------------------------------------------------------===//
namespace {
// Represents a source range within a pair of NOLINT(BEGIN/END) comments.
class NoLintBlockToken {
public:
NoLintBlockToken(NoLintToken Begin, const NoLintToken &End)
: Begin(std::move(Begin)), EndPos(End.Pos) {
assert(this->Begin.Type == NoLintType::NoLintBegin);
assert(End.Type == NoLintType::NoLintEnd);
assert(this->Begin.Pos < End.Pos);
assert(this->Begin.checks() == End.checks());
}
// Whether the provided diagnostic is within and is suppressible by this block
// of NOLINT(BEGIN/END) comments.
bool suppresses(size_t DiagPos, StringRef DiagName) const {
return (Begin.Pos < DiagPos) && (DiagPos < EndPos) &&
Begin.suppresses(DiagName);
}
private:
NoLintToken Begin;
size_t EndPos;
};
} // namespace
// Match NOLINTBEGINs with their corresponding NOLINTENDs and move them into
// `NoLintBlockToken`s. If any BEGINs or ENDs are left over, they are moved to
// `UnmatchedTokens`.
static SmallVector<NoLintBlockToken>
formNoLintBlocks(SmallVector<NoLintToken> NoLints,
SmallVectorImpl<NoLintToken> &UnmatchedTokens) {
SmallVector<NoLintBlockToken> CompletedBlocks;
SmallVector<NoLintToken> Stack;
// Nested blocks must be fully contained within their parent block. What this
// means is that when you have a series of nested BEGIN tokens, the END tokens
// shall appear in the reverse order, starting with the closing of the
// inner-most block first, then the next level up, and so on. This is
// essentially a last-in-first-out/stack system.
for (NoLintToken &NoLint : NoLints) {
if (NoLint.Type == NoLintType::NoLintBegin)
// A new block is being started. Add it to the stack.
Stack.emplace_back(std::move(NoLint));
else if (NoLint.Type == NoLintType::NoLintEnd) {
if (!Stack.empty() && Stack.back().checks() == NoLint.checks())
// The previous block is being closed. Pop one element off the stack.
CompletedBlocks.emplace_back(Stack.pop_back_val(), NoLint);
else
// Trying to close the wrong block.
UnmatchedTokens.emplace_back(std::move(NoLint));
}
}
llvm::move(Stack, std::back_inserter(UnmatchedTokens));
return CompletedBlocks;
}
//===----------------------------------------------------------------------===//
// NoLintDirectiveHandler::Impl
//===----------------------------------------------------------------------===//
class NoLintDirectiveHandler::Impl {
public:
bool shouldSuppress(DiagnosticsEngine::Level DiagLevel,
const Diagnostic &Diag, StringRef DiagName,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
bool AllowIO, bool EnableNoLintBlocks);
private:
bool diagHasNoLintInMacro(const Diagnostic &Diag, StringRef DiagName,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
bool AllowIO, bool EnableNoLintBlocks);
bool diagHasNoLint(StringRef DiagName, SourceLocation DiagLoc,
const SourceManager &SrcMgr,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
bool AllowIO, bool EnableNoLintBlocks);
void generateCache(const SourceManager &SrcMgr, StringRef FileName,
FileID File, StringRef Buffer,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors);
llvm::StringMap<SmallVector<NoLintBlockToken>> Cache;
};
bool NoLintDirectiveHandler::Impl::shouldSuppress(
DiagnosticsEngine::Level DiagLevel, const Diagnostic &Diag,
StringRef DiagName, SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
bool AllowIO, bool EnableNoLintBlocks) {
if (DiagLevel >= DiagnosticsEngine::Error)
return false;
return diagHasNoLintInMacro(Diag, DiagName, NoLintErrors, AllowIO,
EnableNoLintBlocks);
}
// Look at the macro's spelling location for a NOLINT. If none is found, keep
// looking up the call stack.
bool NoLintDirectiveHandler::Impl::diagHasNoLintInMacro(
const Diagnostic &Diag, StringRef DiagName,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors, bool AllowIO,
bool EnableNoLintBlocks) {
SourceLocation DiagLoc = Diag.getLocation();
if (DiagLoc.isInvalid())
return false;
const SourceManager &SrcMgr = Diag.getSourceManager();
while (true) {
if (diagHasNoLint(DiagName, DiagLoc, SrcMgr, NoLintErrors, AllowIO,
EnableNoLintBlocks))
return true;
if (!DiagLoc.isMacroID())
return false;
DiagLoc = SrcMgr.getImmediateExpansionRange(DiagLoc).getBegin();
}
return false;
}
// Look behind and ahead for '\n' characters. These mark the start and end of
// this line.
static std::pair<size_t, size_t> getLineStartAndEnd(StringRef Buffer,
size_t From) {
size_t StartPos = Buffer.find_last_of('\n', From) + 1;
size_t EndPos = std::min(Buffer.find('\n', From), Buffer.size());
return std::make_pair(StartPos, EndPos);
}
// Whether the line has a NOLINT of type = `Type` that can suppress the
// diagnostic `DiagName`.
static bool lineHasNoLint(StringRef Buffer,
std::pair<size_t, size_t> LineStartAndEnd,
NoLintType Type, StringRef DiagName) {
// Get all NOLINTs on the line.
Buffer = Buffer.slice(LineStartAndEnd.first, LineStartAndEnd.second);
SmallVector<NoLintToken> NoLints = getNoLints(Buffer);
// Do any of these NOLINTs match the desired type and diag name?
return llvm::any_of(NoLints, [&](const NoLintToken &NoLint) {
return NoLint.Type == Type && NoLint.suppresses(DiagName);
});
}
// Whether the provided diagnostic is located within and is suppressible by a
// block of NOLINT(BEGIN/END) comments.
static bool withinNoLintBlock(ArrayRef<NoLintBlockToken> NoLintBlocks,
size_t DiagPos, StringRef DiagName) {
return llvm::any_of(NoLintBlocks, [&](const NoLintBlockToken &NoLintBlock) {
return NoLintBlock.suppresses(DiagPos, DiagName);
});
}
// Get the file contents as a string.
static std::optional<StringRef> getBuffer(const SourceManager &SrcMgr,
FileID File, bool AllowIO) {
return AllowIO ? SrcMgr.getBufferDataOrNone(File)
: SrcMgr.getBufferDataIfLoaded(File);
}
// We will check for NOLINTs and NOLINTNEXTLINEs first. Checking for these is
// not so expensive (just need to parse the current and previous lines). Only if
// that fails do we look for NOLINT(BEGIN/END) blocks (which requires reading
// the entire file).
bool NoLintDirectiveHandler::Impl::diagHasNoLint(
StringRef DiagName, SourceLocation DiagLoc, const SourceManager &SrcMgr,
SmallVectorImpl<tooling::Diagnostic> &NoLintErrors, bool AllowIO,
bool EnableNoLintBlocks) {
// Translate the diagnostic's SourceLocation to a raw file + offset pair.
FileID File;
unsigned int Pos = 0;
std::tie(File, Pos) = SrcMgr.getDecomposedSpellingLoc(DiagLoc);
// We will only see NOLINTs in user-authored sources. No point reading the
// file if it is a <built-in>.
std::optional<StringRef> FileName = SrcMgr.getNonBuiltinFilenameForID(File);
if (!FileName)
return false;
// Get file contents.
std::optional<StringRef> Buffer = getBuffer(SrcMgr, File, AllowIO);
if (!Buffer)
return false;
// Check if there's a NOLINT on this line.
auto ThisLine = getLineStartAndEnd(*Buffer, Pos);
if (lineHasNoLint(*Buffer, ThisLine, NoLintType::NoLint, DiagName))
return true;
// Check if there's a NOLINTNEXTLINE on the previous line.
if (ThisLine.first > 0) {
auto PrevLine = getLineStartAndEnd(*Buffer, ThisLine.first - 1);
if (lineHasNoLint(*Buffer, PrevLine, NoLintType::NoLintNextLine, DiagName))
return true;
}
// Check if this line is within a NOLINT(BEGIN/END) block.
if (!EnableNoLintBlocks)
return false;
// Do we have cached NOLINT block locations for this file?
if (Cache.count(*FileName) == 0)
// Warning: heavy operation - need to read entire file.
generateCache(SrcMgr, *FileName, File, *Buffer, NoLintErrors);
return withinNoLintBlock(Cache[*FileName], Pos, DiagName);
}
// Construct a [clang-tidy-nolint] diagnostic to do with the unmatched
// NOLINT(BEGIN/END) pair.
static tooling::Diagnostic makeNoLintError(const SourceManager &SrcMgr,
FileID File,
const NoLintToken &NoLint) {
tooling::Diagnostic Error;
Error.DiagLevel = tooling::Diagnostic::Error;
Error.DiagnosticName = "clang-tidy-nolint";
StringRef Message =
(NoLint.Type == NoLintType::NoLintBegin)
? ("unmatched 'NOLINTBEGIN' comment without a subsequent 'NOLINT"
"END' comment")
: ("unmatched 'NOLINTEND' comment without a previous 'NOLINT"
"BEGIN' comment");
SourceLocation Loc = SrcMgr.getComposedLoc(File, NoLint.Pos);
Error.Message = tooling::DiagnosticMessage(Message, SrcMgr, Loc);
return Error;
}
// Find all NOLINT(BEGIN/END) blocks in a file and store in the cache.
void NoLintDirectiveHandler::Impl::generateCache(
const SourceManager &SrcMgr, StringRef FileName, FileID File,
StringRef Buffer, SmallVectorImpl<tooling::Diagnostic> &NoLintErrors) {
// Read entire file to get all NOLINTs.
SmallVector<NoLintToken> NoLints = getNoLints(Buffer);
// Match each BEGIN with its corresponding END.
SmallVector<NoLintToken> UnmatchedTokens;
Cache[FileName] = formNoLintBlocks(std::move(NoLints), UnmatchedTokens);
// Raise error for any BEGIN/END left over.
for (const NoLintToken &NoLint : UnmatchedTokens)
NoLintErrors.emplace_back(makeNoLintError(SrcMgr, File, NoLint));
}
//===----------------------------------------------------------------------===//
// NoLintDirectiveHandler
//===----------------------------------------------------------------------===//
NoLintDirectiveHandler::NoLintDirectiveHandler()
: PImpl(std::make_unique<Impl>()) {}
NoLintDirectiveHandler::~NoLintDirectiveHandler() = default;
bool NoLintDirectiveHandler::shouldSuppress(
DiagnosticsEngine::Level DiagLevel, const Diagnostic &Diag,
StringRef DiagName, SmallVectorImpl<tooling::Diagnostic> &NoLintErrors,
bool AllowIO, bool EnableNoLintBlocks) {
return PImpl->shouldSuppress(DiagLevel, Diag, DiagName, NoLintErrors, AllowIO,
EnableNoLintBlocks);
}
} // namespace clang::tidy
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