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[clang-tidy] Add new check readability-use-numeric-limits (#127430)
The adds a check that replaces specific numeric literals like `32767` with the equivalent call to `std::numeric_limits` (such as `std::numeric_limits<int16_t>::max())`. Partially addresses #34434, but notably does not handle cases listed in the title post such as `~0` and `-1`.
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‎clang-tools-extra/clang-tidy/readability/CMakeLists.txt

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@@ -58,6 +58,7 @@ add_clang_library(clangTidyReadabilityModule STATIC
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UniqueptrDeleteReleaseCheck.cpp
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UppercaseLiteralSuffixCheck.cpp
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UseAnyOfAllOfCheck.cpp
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UseNumericLimitsCheck.cpp
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UseStdMinMaxCheck.cpp
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LINK_LIBS

‎clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

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@@ -61,6 +61,7 @@
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#include "UniqueptrDeleteReleaseCheck.h"
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#include "UppercaseLiteralSuffixCheck.h"
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#include "UseAnyOfAllOfCheck.h"
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#include "UseNumericLimitsCheck.h"
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#include "UseStdMinMaxCheck.h"
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namespace clang::tidy {
@@ -173,6 +174,8 @@ class ReadabilityModule : public ClangTidyModule {
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"readability-uppercase-literal-suffix");
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CheckFactories.registerCheck<UseAnyOfAllOfCheck>(
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"readability-use-anyofallof");
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CheckFactories.registerCheck<UseNumericLimitsCheck>(
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"readability-use-numeric-limits");
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CheckFactories.registerCheck<UseStdMinMaxCheck>(
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"readability-use-std-min-max");
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}

‎clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.cpp

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//===--- UseNumericLimitsCheck.cpp - clang-tidy ---------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "UseNumericLimitsCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Lex/Preprocessor.h"
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#include <cmath>
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#include <limits>
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using namespace clang::ast_matchers;
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namespace clang::tidy::readability {
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UseNumericLimitsCheck::UseNumericLimitsCheck(StringRef Name,
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ClangTidyContext *Context)
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: ClangTidyCheck(Name, Context),
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SignedConstants{
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{std::numeric_limits<int8_t>::min(),
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"std::numeric_limits<int8_t>::min()"},
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{std::numeric_limits<int8_t>::max(),
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"std::numeric_limits<int8_t>::max()"},
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{std::numeric_limits<int16_t>::min(),
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"std::numeric_limits<int16_t>::min()"},
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{std::numeric_limits<int16_t>::max(),
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"std::numeric_limits<int16_t>::max()"},
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{std::numeric_limits<int32_t>::min(),
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"std::numeric_limits<int32_t>::min()"},
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{std::numeric_limits<int32_t>::max(),
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"std::numeric_limits<int32_t>::max()"},
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{std::numeric_limits<int64_t>::min(),
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"std::numeric_limits<int64_t>::min()"},
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{std::numeric_limits<int64_t>::max(),
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"std::numeric_limits<int64_t>::max()"},
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},
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UnsignedConstants{
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{std::numeric_limits<uint8_t>::max(),
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"std::numeric_limits<uint8_t>::max()"},
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{std::numeric_limits<uint16_t>::max(),
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"std::numeric_limits<uint16_t>::max()"},
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{std::numeric_limits<uint32_t>::max(),
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"std::numeric_limits<uint32_t>::max()"},
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{std::numeric_limits<uint64_t>::max(),
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"std::numeric_limits<uint64_t>::max()"},
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},
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Inserter(Options.getLocalOrGlobal("IncludeStyle",
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utils::IncludeSorter::IS_LLVM),
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areDiagsSelfContained()) {}
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void UseNumericLimitsCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
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Options.store(Opts, "IncludeStyle", Inserter.getStyle());
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}
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void UseNumericLimitsCheck::registerMatchers(MatchFinder *Finder) {
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auto PositiveIntegerMatcher = [](auto Value) {
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return unaryOperator(hasOperatorName("+"),
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hasUnaryOperand(integerLiteral(equals(Value))
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.bind("positive-integer-literal")))
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.bind("unary-op");
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};
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auto NegativeIntegerMatcher = [](auto Value) {
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return unaryOperator(hasOperatorName("-"),
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hasUnaryOperand(integerLiteral(equals(-Value))
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.bind("negative-integer-literal")))
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.bind("unary-op");
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};
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auto BareIntegerMatcher = [](auto Value) {
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return integerLiteral(allOf(unless(hasParent(unaryOperator(
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hasAnyOperatorName("-", "+")))),
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equals(Value)))
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.bind("bare-integer-literal");
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};
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for (const auto &[Value, _] : SignedConstants) {
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if (Value < 0) {
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Finder->addMatcher(NegativeIntegerMatcher(Value), this);
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} else {
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Finder->addMatcher(
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expr(anyOf(PositiveIntegerMatcher(Value), BareIntegerMatcher(Value))),
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this);
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}
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}
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for (const auto &[Value, _] : UnsignedConstants) {
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Finder->addMatcher(
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expr(anyOf(PositiveIntegerMatcher(Value), BareIntegerMatcher(Value))),
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this);
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}
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}
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void UseNumericLimitsCheck::registerPPCallbacks(
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const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
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Inserter.registerPreprocessor(PP);
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}
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void UseNumericLimitsCheck::check(const MatchFinder::MatchResult &Result) {
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const IntegerLiteral *MatchedDecl = nullptr;
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const IntegerLiteral *NegativeMatchedDecl =
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Result.Nodes.getNodeAs<IntegerLiteral>("negative-integer-literal");
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const IntegerLiteral *PositiveMatchedDecl =
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Result.Nodes.getNodeAs<IntegerLiteral>("positive-integer-literal");
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const IntegerLiteral *BareMatchedDecl =
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Result.Nodes.getNodeAs<IntegerLiteral>("bare-integer-literal");
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if (NegativeMatchedDecl != nullptr)
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MatchedDecl = NegativeMatchedDecl;
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else if (PositiveMatchedDecl != nullptr)
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MatchedDecl = PositiveMatchedDecl;
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else if (BareMatchedDecl != nullptr)
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MatchedDecl = BareMatchedDecl;
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const llvm::APInt MatchedIntegerConstant = MatchedDecl->getValue();
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auto Fixer = [&](auto SourceValue, auto Value,
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const std::string &Replacement) {
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static_assert(std::is_same_v<decltype(SourceValue), decltype(Value)>,
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"The types of SourceValue and Value must match");
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SourceLocation Location = MatchedDecl->getExprLoc();
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SourceRange Range{MatchedDecl->getBeginLoc(), MatchedDecl->getEndLoc()};
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// Only valid if unary operator is present
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const UnaryOperator *UnaryOpExpr =
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Result.Nodes.getNodeAs<UnaryOperator>("unary-op");
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if (MatchedDecl == NegativeMatchedDecl && -SourceValue == Value) {
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Range = SourceRange(UnaryOpExpr->getBeginLoc(), UnaryOpExpr->getEndLoc());
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Location = UnaryOpExpr->getExprLoc();
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SourceValue = -SourceValue;
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} else if (MatchedDecl == PositiveMatchedDecl && SourceValue == Value) {
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Range = SourceRange(UnaryOpExpr->getBeginLoc(), UnaryOpExpr->getEndLoc());
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Location = UnaryOpExpr->getExprLoc();
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} else if (MatchedDecl != BareMatchedDecl || SourceValue != Value) {
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return;
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}
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diag(Location,
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"the constant '%0' is being utilized; consider using '%1' instead")
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<< SourceValue << Replacement
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<< FixItHint::CreateReplacement(Range, Replacement)
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<< Inserter.createIncludeInsertion(
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Result.SourceManager->getFileID(Location), "<limits>");
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};
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for (const auto &[Value, Replacement] : SignedConstants)
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Fixer(MatchedIntegerConstant.getSExtValue(), Value, Replacement);
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for (const auto &[Value, Replacement] : UnsignedConstants)
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Fixer(MatchedIntegerConstant.getZExtValue(), Value, Replacement);
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}
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} // namespace clang::tidy::readability

‎clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.h

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//===--- UseNumericLimitsCheck.h - clang-tidy -------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H
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#include "../ClangTidyCheck.h"
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#include "../utils/IncludeInserter.h"
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namespace clang::tidy::readability {
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/// Finds certain integer literals and suggests replacing them with equivalent
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/// ``std::numeric_limits`` calls.
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/// For the user-facing documentation see:
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/// http://clang.llvm.org/extra/clang-tidy/checks/readability/use-numeric-limits.html
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class UseNumericLimitsCheck : public ClangTidyCheck {
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public:
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UseNumericLimitsCheck(StringRef Name, ClangTidyContext *Context);
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void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
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void registerMatchers(ast_matchers::MatchFinder *Finder) override;
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void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
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Preprocessor *ModuleExpanderPP) override;
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void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
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private:
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const llvm::SmallVector<std::pair<int64_t, std::string>> SignedConstants;
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const llvm::SmallVector<std::pair<uint64_t, std::string>> UnsignedConstants;
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utils::IncludeInserter Inserter;
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};
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} // namespace clang::tidy::readability
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H

‎clang-tools-extra/docs/ReleaseNotes.rst

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@@ -154,6 +154,12 @@ New checks
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Finds potentially erroneous calls to ``reset`` method on smart pointers when
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the pointee type also has a ``reset`` method.
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- New :doc:`readability-use-numeric-limits
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<clang-tidy/checks/readability/use-numeric-limits>` check.
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Finds certain integer literals and suggests replacing them with equivalent
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``std::numeric_limits`` calls.
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New check aliases
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^^^^^^^^^^^^^^^^^
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‎clang-tools-extra/docs/clang-tidy/checks/list.rst

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@@ -409,6 +409,7 @@ Clang-Tidy Checks
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:doc:`readability-uniqueptr-delete-release <readability/uniqueptr-delete-release>`, "Yes"
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:doc:`readability-uppercase-literal-suffix <readability/uppercase-literal-suffix>`, "Yes"
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:doc:`readability-use-anyofallof <readability/use-anyofallof>`,
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:doc:`readability-use-numeric-limits <readability/use-numeric-limits>`, "Yes"
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:doc:`readability-use-std-min-max <readability/use-std-min-max>`, "Yes"
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:doc:`zircon-temporary-objects <zircon/temporary-objects>`,
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‎clang-tools-extra/docs/clang-tidy/checks/readability/use-numeric-limits.rst

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.. title:: clang-tidy - readability-use-numeric-limits
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readability-use-numeric-limits
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==============================
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Finds certain integer literals and suggests replacing them with equivalent
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``std::numeric_limits`` calls.
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Before:
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.. code-block:: c++
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void foo() {
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int32_t a = 2147483647;
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}
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After:
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.. code-block:: c++
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void foo() {
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int32_t a = std::numeric_limits<int32_t>::max();
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}
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Options
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-------
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.. option:: IncludeStyle
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A string specifying which include-style is used, `llvm` or `google`. Default
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is `llvm`.

‎clang-tools-extra/test/clang-tidy/checkers/readability/use-numeric-limits.cpp

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// RUN: %check_clang_tidy %s readability-use-numeric-limits %t
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// CHECK-FIXES: #include <limits>
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using int8_t = signed char;
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using int16_t = short;
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using int32_t = int;
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using int64_t = long long;
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using uint8_t = unsigned char;
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using uint16_t = unsigned short;
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using uint32_t = unsigned int;
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using uint64_t = unsigned long long;
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void Invalid() {
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// CHECK-MESSAGES: :[[@LINE+2]]:14: warning: the constant '-128' is being utilized; consider using 'std::numeric_limits<int8_t>::min()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int8_t a = std::numeric_limits<int8_t>::min();
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int8_t a = -128;
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// CHECK-MESSAGES: :[[@LINE+2]]:14: warning: the constant '127' is being utilized; consider using 'std::numeric_limits<int8_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int8_t b = std::numeric_limits<int8_t>::max();
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int8_t b = +127;
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// CHECK-MESSAGES: :[[@LINE+2]]:14: warning: the constant '127' is being utilized; consider using 'std::numeric_limits<int8_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int8_t c = std::numeric_limits<int8_t>::max();
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int8_t c = 127;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '-32768' is being utilized; consider using 'std::numeric_limits<int16_t>::min()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int16_t d = std::numeric_limits<int16_t>::min();
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int16_t d = -32768;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '32767' is being utilized; consider using 'std::numeric_limits<int16_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int16_t e = std::numeric_limits<int16_t>::max();
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int16_t e = +32767;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '32767' is being utilized; consider using 'std::numeric_limits<int16_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int16_t f = std::numeric_limits<int16_t>::max();
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int16_t f = 32767;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '-2147483648' is being utilized; consider using 'std::numeric_limits<int32_t>::min()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int32_t g = std::numeric_limits<int32_t>::min();
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int32_t g = -2147483648;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '2147483647' is being utilized; consider using 'std::numeric_limits<int32_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int32_t h = std::numeric_limits<int32_t>::max();
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int32_t h = +2147483647;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '2147483647' is being utilized; consider using 'std::numeric_limits<int32_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int32_t i = std::numeric_limits<int32_t>::max();
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int32_t i = 2147483647;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '-9223372036854775808' is being utilized; consider using 'std::numeric_limits<int64_t>::min()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int64_t j = std::numeric_limits<int64_t>::min();
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int64_t j = -9223372036854775808;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '9223372036854775807' is being utilized; consider using 'std::numeric_limits<int64_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int64_t k = std::numeric_limits<int64_t>::max();
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int64_t k = +9223372036854775807;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '9223372036854775807' is being utilized; consider using 'std::numeric_limits<int64_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: int64_t l = std::numeric_limits<int64_t>::max();
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int64_t l = 9223372036854775807;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '255' is being utilized; consider using 'std::numeric_limits<uint8_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint8_t m = std::numeric_limits<uint8_t>::max();
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uint8_t m = 255;
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// CHECK-MESSAGES: :[[@LINE+2]]:15: warning: the constant '255' is being utilized; consider using 'std::numeric_limits<uint8_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint8_t n = std::numeric_limits<uint8_t>::max();
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uint8_t n = +255;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '65535' is being utilized; consider using 'std::numeric_limits<uint16_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint16_t o = std::numeric_limits<uint16_t>::max();
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uint16_t o = 65535;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '65535' is being utilized; consider using 'std::numeric_limits<uint16_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint16_t p = std::numeric_limits<uint16_t>::max();
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uint16_t p = +65535;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '4294967295' is being utilized; consider using 'std::numeric_limits<uint32_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint32_t q = std::numeric_limits<uint32_t>::max();
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uint32_t q = 4294967295;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '4294967295' is being utilized; consider using 'std::numeric_limits<uint32_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint32_t r = std::numeric_limits<uint32_t>::max();
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uint32_t r = +4294967295;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '18446744073709551615' is being utilized; consider using 'std::numeric_limits<uint64_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint64_t s = std::numeric_limits<uint64_t>::max();
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uint64_t s = 18446744073709551615;
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// CHECK-MESSAGES: :[[@LINE+2]]:16: warning: the constant '18446744073709551615' is being utilized; consider using 'std::numeric_limits<uint64_t>::max()' instead [readability-use-numeric-limits]
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// CHECK-FIXES: uint64_t t = std::numeric_limits<uint64_t>::max();
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uint64_t t = +18446744073709551615;
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}
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void Valid(){
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int16_t a = +128;
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int16_t b = -127;
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}

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