UppercaseLiteralSuffixCheck.cpp

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//===----------------------------------------------------------------------===//
//
// 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 "UppercaseLiteralSuffixCheck.h"
#include "../utils/ASTUtils.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
#include <optional>
 
using namespace clang::ast_matchers;
 
namespace clang::tidy::readability {
 
namespace {
 
struct NewSuffix {
  SourceRange LiteralLocation;
  StringRef OldSuffix;
  std::optional<FixItHint> FixIt;
};
 
struct LiteralParameters {
  // What characters should be skipped before looking for the Suffixes?
  StringRef SkipFirst;
  // What characters can a suffix start with?
  StringRef Suffixes;
};
 
} // namespace
 
static constexpr LiteralParameters IntegerParameters = {
    "",
    // Suffix can only consist of 'u', 'l', and 'z' chars, can be a
    // bit-precise integer (wb), and can be a complex number ('i', 'j'). In MS
    // compatibility mode, suffixes like i32 are supported.
    "uUlLzZwWiIjJ",
};
 
static constexpr LiteralParameters FloatParameters = {
    // C++17 introduced hexadecimal floating-point literals, and 'f' is both a
    // valid hexadecimal digit in a hex float literal and a valid floating-point
    // literal suffix.
    // So we can't just "skip to the chars that can be in the suffix".
    // Since the exponent ('p'/'P') is mandatory for hexadecimal floating-point
    // literals, we first skip everything before the exponent.
    "pP",
    // Suffix can only consist of 'f', 'l', "f16", "bf16", "df", "dd", "dl",
    // 'h', 'q' chars, and can be a complex number ('i', 'j').
    "fFlLbBdDhHqQiIjJ",
};
 
static std::optional<SourceLocation>
getMacroAwareLocation(SourceLocation Loc, const SourceManager &SM) {
  // Do nothing if the provided location is invalid.
  if (Loc.isInvalid())
    return std::nullopt;
  // Look where the location was *actually* written.
  SourceLocation SpellingLoc = SM.getSpellingLoc(Loc);
  if (SpellingLoc.isInvalid())
    return std::nullopt;
  return SpellingLoc;
}
 
static std::optional<SourceRange>
getMacroAwareSourceRange(SourceRange Loc, const SourceManager &SM) {
  std::optional<SourceLocation> Begin =
      getMacroAwareLocation(Loc.getBegin(), SM);
  std::optional<SourceLocation> End = getMacroAwareLocation(Loc.getEnd(), SM);
  if (!Begin || !End)
    return std::nullopt;
  return SourceRange(*Begin, *End);
}
 
static std::optional<std::string>
getNewSuffix(StringRef OldSuffix, const std::vector<StringRef> &NewSuffixes) {
  // If there is no config, just uppercase the entirety of the suffix.
  if (NewSuffixes.empty())
    return OldSuffix.upper();
  // Else, find matching suffix, case-*insensitive*ly.
  auto NewSuffix =
      llvm::find_if(NewSuffixes, [OldSuffix](StringRef PotentialNewSuffix) {
        return OldSuffix.equals_insensitive(PotentialNewSuffix);
      });
  // Have a match, return it.
  if (NewSuffix != NewSuffixes.end())
    return NewSuffix->str();
  // Nope, I guess we have to keep it as-is.
  return std::nullopt;
}
 
static std::optional<NewSuffix>
shouldReplaceLiteralSuffix(const Expr &Literal,
                           const LiteralParameters &Parameters,
                           const std::vector<StringRef> &NewSuffixes,
                           const SourceManager &SM, const LangOptions &LO) {
  NewSuffix ReplacementDsc;
 
  // The naive location of the literal. Is always valid.
  ReplacementDsc.LiteralLocation = Literal.getSourceRange();
 
  // Was this literal fully spelled or is it a product of macro expansion?
  const bool RangeCanBeFixed =
      utils::rangeCanBeFixed(ReplacementDsc.LiteralLocation, &SM);
 
  // The literal may have macro expansion, we need the final expanded src range.
  std::optional<SourceRange> Range =
      getMacroAwareSourceRange(ReplacementDsc.LiteralLocation, SM);
  if (!Range)
    return std::nullopt;
 
  if (RangeCanBeFixed)
    ReplacementDsc.LiteralLocation = *Range;
  // Else keep the naive literal location!
 
  // Get the whole literal from the source buffer.
  bool Invalid = false;
  const StringRef LiteralSourceText = Lexer::getSourceText(
      CharSourceRange::getTokenRange(*Range), SM, LO, &Invalid);
  assert(!Invalid && "Failed to retrieve the source text.");
 
  // Make sure the first character is actually a digit, instead of
  // something else, like a non-type template parameter.
  if (!std::isdigit(static_cast<unsigned char>(LiteralSourceText.front())))
    return std::nullopt;
 
  size_t Skip = 0;
 
  // Do we need to ignore something before actually looking for the suffix?
  if (!Parameters.SkipFirst.empty()) {
    // E.g. we can't look for 'f' suffix in hexadecimal floating-point literals
    // until after we skip to the exponent (which is mandatory there),
    // because hex-digit-sequence may contain 'f'.
    Skip = LiteralSourceText.find_first_of(Parameters.SkipFirst);
    // We could be in non-hexadecimal floating-point literal, with no exponent.
    if (Skip == StringRef::npos)
      Skip = 0;
  }
 
  // Find the beginning of the suffix by looking for the first char that is
  // one of these chars that can be in the suffix, potentially starting looking
  // in the exponent, if we are skipping hex-digit-sequence.
  Skip = LiteralSourceText.find_first_of(Parameters.Suffixes, /*From=*/Skip);
 
  // We can't check whether the *Literal has any suffix or not without actually
  // looking for the suffix. So it is totally possible that there is no suffix.
  if (Skip == StringRef::npos)
    return std::nullopt;
 
  // Move the cursor in the source range to the beginning of the suffix.
  Range->setBegin(Range->getBegin().getLocWithOffset(Skip));
  // And in our textual representation too.
  ReplacementDsc.OldSuffix = LiteralSourceText.drop_front(Skip);
  assert(!ReplacementDsc.OldSuffix.empty() &&
         "We still should have some chars left.");
 
  // And get the replacement suffix.
  std::optional<std::string> NewSuffix =
      getNewSuffix(ReplacementDsc.OldSuffix, NewSuffixes);
  if (!NewSuffix || ReplacementDsc.OldSuffix == *NewSuffix)
    return std::nullopt; // The suffix was already the way it should be.
 
  if (RangeCanBeFixed)
    ReplacementDsc.FixIt = FixItHint::CreateReplacement(*Range, *NewSuffix);
 
  return ReplacementDsc;
}
 
UppercaseLiteralSuffixCheck::UppercaseLiteralSuffixCheck(
    StringRef Name, ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      NewSuffixes(
          utils::options::parseStringList(Options.get("NewSuffixes", ""))),
      IgnoreMacros(Options.get("IgnoreMacros", true)) {}
 
void UppercaseLiteralSuffixCheck::storeOptions(
    ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "NewSuffixes",
                utils::options::serializeStringList(NewSuffixes));
  Options.store(Opts, "IgnoreMacros", IgnoreMacros);
}
 
void UppercaseLiteralSuffixCheck::registerMatchers(MatchFinder *Finder) {
  // Sadly, we can't check whether the literal has suffix or not.
  // E.g. i32 suffix still results in 'BuiltinType::Kind::Int'.
  // And such an info is not stored in the *Literal itself.
 
  Finder->addMatcher(
      integerLiteral(unless(hasParent(userDefinedLiteral()))).bind("expr"),
      this);
  Finder->addMatcher(
      floatLiteral(unless(hasParent(userDefinedLiteral()))).bind("expr"), this);
}
 
void UppercaseLiteralSuffixCheck::check(
    const MatchFinder::MatchResult &Result) {
  const auto *const Literal = Result.Nodes.getNodeAs<Expr>("expr");
  const bool IsInteger = isa<IntegerLiteral>(Literal);
 
  // We won't *always* want to diagnose.
  // We might have a suffix that is already uppercase.
  if (auto Details = shouldReplaceLiteralSuffix(
          *Literal, IsInteger ? IntegerParameters : FloatParameters,
          NewSuffixes, *Result.SourceManager, getLangOpts())) {
    if (Details->LiteralLocation.getBegin().isMacroID() && IgnoreMacros)
      return;
    auto Complaint = diag(Details->LiteralLocation.getBegin(),
                          "%select{floating point|integer}0 literal has suffix "
                          "'%1', which is not uppercase")
                     << IsInteger << Details->OldSuffix;
    if (Details->FixIt) // Similarly, a fix-it is not always possible.
      Complaint << *(Details->FixIt);
  }
}
 
} // namespace clang::tidy::readability