[clang-tools-extra] [clang-tidy] Add new check `readability-use-numeric-limits` (PR #127430)
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cfe-commits at lists.llvm.org
Sun Feb 16 19:56:46 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tools-extra
@llvm/pr-subscribers-clang-tidy
Author: Katherine Whitlock (stellar-aria)
<details>
<summary>Changes</summary>
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`.
---
Full diff: https://github.com/llvm/llvm-project/pull/127430.diff
8 Files Affected:
- (modified) clang-tools-extra/clang-tidy/readability/CMakeLists.txt (+1)
- (modified) clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp (+3)
- (added) clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.cpp (+135)
- (added) clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.h (+41)
- (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
- (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
- (added) clang-tools-extra/docs/clang-tidy/checks/readability/use-numeric-limits.rst (+22)
- (added) clang-tools-extra/test/clang-tidy/checkers/readability/use-numeric-limits.cpp (+85)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
index 8f303c51e1b0d..e06f68bdda73f 100644
--- a/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/readability/CMakeLists.txt
@@ -57,6 +57,7 @@ add_clang_library(clangTidyReadabilityModule STATIC
UniqueptrDeleteReleaseCheck.cpp
UppercaseLiteralSuffixCheck.cpp
UseAnyOfAllOfCheck.cpp
+ UseNumericLimitsCheck.cpp
UseStdMinMaxCheck.cpp
LINK_LIBS
diff --git a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
index d61c0ba39658e..054083d25952a 100644
--- a/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -60,6 +60,7 @@
#include "UniqueptrDeleteReleaseCheck.h"
#include "UppercaseLiteralSuffixCheck.h"
#include "UseAnyOfAllOfCheck.h"
+#include "UseNumericLimitsCheck.h"
#include "UseStdMinMaxCheck.h"
namespace clang::tidy {
@@ -170,6 +171,8 @@ class ReadabilityModule : public ClangTidyModule {
"readability-uppercase-literal-suffix");
CheckFactories.registerCheck<UseAnyOfAllOfCheck>(
"readability-use-anyofallof");
+ CheckFactories.registerCheck<UseNumericLimitsCheck>(
+ "readability-use-numeric-limits");
CheckFactories.registerCheck<UseStdMinMaxCheck>(
"readability-use-std-min-max");
}
diff --git a/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.cpp b/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.cpp
new file mode 100644
index 0000000000000..b26ae008cbdd5
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.cpp
@@ -0,0 +1,135 @@
+//===--- UseNumericLimitsCheck.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 "UseNumericLimitsCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Preprocessor.h"
+#include <cmath>
+#include <limits>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+UseNumericLimitsCheck::UseNumericLimitsCheck(StringRef Name,
+ ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ SignedConstants{
+ {std::numeric_limits<int8_t>::min(),
+ "std::numeric_limits<int8_t>::min()"},
+ {std::numeric_limits<int8_t>::max(),
+ "std::numeric_limits<int8_t>::max()"},
+ {std::numeric_limits<int16_t>::min(),
+ "std::numeric_limits<int16_t>::min()"},
+ {std::numeric_limits<int16_t>::max(),
+ "std::numeric_limits<int16_t>::max()"},
+ {std::numeric_limits<int32_t>::min(),
+ "std::numeric_limits<int32_t>::min()"},
+ {std::numeric_limits<int32_t>::max(),
+ "std::numeric_limits<int32_t>::max()"},
+ {std::numeric_limits<int64_t>::min(),
+ "std::numeric_limits<int64_t>::min()"},
+ {std::numeric_limits<int64_t>::max(),
+ "std::numeric_limits<int64_t>::max()"},
+
+ },
+ UnsignedConstants{
+ {std::numeric_limits<uint8_t>::max(),
+ "std::numeric_limits<uint8_t>::max()"},
+ {std::numeric_limits<uint16_t>::max(),
+ "std::numeric_limits<uint16_t>::max()"},
+ {std::numeric_limits<uint32_t>::max(),
+ "std::numeric_limits<uint32_t>::max()"},
+ {std::numeric_limits<uint64_t>::max(),
+ "std::numeric_limits<uint64_t>::max()"},
+ },
+ Inserter(Options.getLocalOrGlobal("IncludeStyle",
+ utils::IncludeSorter::IS_LLVM),
+ areDiagsSelfContained()) {}
+
+void UseNumericLimitsCheck::registerMatchers(MatchFinder *Finder) {
+ Finder->addMatcher(
+ expr(anyOf(unaryOperator(hasOperatorName("-"),
+ hasUnaryOperand(integerLiteral().bind(
+ "negative-integer-literal"))),
+ unaryOperator(hasOperatorName("+"),
+ hasUnaryOperand(integerLiteral().bind(
+ "positive-integer-literal"))),
+ integerLiteral(unless(hasParent(unaryOperator(
+ hasAnyOperatorName("-", "+")))))
+ .bind("bare-integer-literal")))
+ .bind("unary-op-exp"),
+ this);
+}
+
+void UseNumericLimitsCheck::registerPPCallbacks(
+ const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+ Inserter.registerPreprocessor(PP);
+}
+
+void UseNumericLimitsCheck::check(const MatchFinder::MatchResult &Result) {
+ const IntegerLiteral *MatchedDecl = nullptr;
+
+ const IntegerLiteral *NegativeMatchedDecl =
+ Result.Nodes.getNodeAs<IntegerLiteral>("negative-integer-literal");
+ const IntegerLiteral *PositiveMatchedDecl =
+ Result.Nodes.getNodeAs<IntegerLiteral>("positive-integer-literal");
+ const IntegerLiteral *BareMatchedDecl =
+ Result.Nodes.getNodeAs<IntegerLiteral>("bare-integer-literal");
+
+ if (NegativeMatchedDecl != nullptr) {
+ MatchedDecl = NegativeMatchedDecl;
+ } else if (PositiveMatchedDecl != nullptr) {
+ MatchedDecl = PositiveMatchedDecl;
+ } else if (BareMatchedDecl != nullptr) {
+ MatchedDecl = BareMatchedDecl;
+ }
+
+ // Only valid if unary operator is present
+ const UnaryOperator *UnaryOpExpr =
+ Result.Nodes.getNodeAs<UnaryOperator>("unary-op-exp");
+
+ const llvm::APInt MatchedIntegerConstant = MatchedDecl->getValue();
+ const auto Language = getLangOpts();
+
+ auto Fixer = [&](auto SourceValue, auto Value,
+ const std::string &Replacement) {
+ SourceLocation Location = MatchedDecl->getExprLoc();
+ SourceRange Range{MatchedDecl->getBeginLoc(), MatchedDecl->getEndLoc()};
+
+ if (MatchedDecl == NegativeMatchedDecl && -SourceValue == Value) {
+ Range = SourceRange(UnaryOpExpr->getBeginLoc(), UnaryOpExpr->getEndLoc());
+ Location = UnaryOpExpr->getExprLoc();
+ SourceValue = -SourceValue;
+ } else if (MatchedDecl == PositiveMatchedDecl && SourceValue == Value) {
+ Range = SourceRange(UnaryOpExpr->getBeginLoc(), UnaryOpExpr->getEndLoc());
+ Location = UnaryOpExpr->getExprLoc();
+ } else if (MatchedDecl != BareMatchedDecl || SourceValue != Value) {
+ return;
+ }
+
+ diag(Location, "The constant " + std::to_string(SourceValue) +
+ " is being utilized. "
+ "Consider using " +
+ Replacement + " instead")
+ << FixItHint::CreateReplacement(Range, Replacement)
+ << Inserter.createIncludeInsertion(
+ Result.SourceManager->getFileID(Location), "<limits>");
+ };
+
+ for (const auto &[Value, Replacement] : SignedConstants) {
+ Fixer(MatchedIntegerConstant.getSExtValue(), Value, Replacement);
+ }
+
+ for (const auto &[Value, Replacement] : UnsignedConstants) {
+ Fixer(MatchedIntegerConstant.getZExtValue(), Value, Replacement);
+ }
+}
+
+} // namespace clang::tidy::readability
diff --git a/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.h b/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.h
new file mode 100644
index 0000000000000..d7231132ef5dd
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/readability/UseNumericLimitsCheck.h
@@ -0,0 +1,41 @@
+//===--- UseNumericLimitsCheck.h - clang-tidy -------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "../utils/IncludeInserter.h"
+#include <vector>
+
+namespace clang::tidy::readability {
+
+/// Replaces certain integer literals with equivalent calls to
+/// ``std::numeric_limits``.
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/use-numeric-limits.html
+class UseNumericLimitsCheck : public ClangTidyCheck {
+public:
+ UseNumericLimitsCheck(StringRef Name, ClangTidyContext *Context);
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+ Preprocessor *ModuleExpanderPP) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus11;
+ }
+
+private:
+ const std::vector<std::tuple<int64_t, std::string>> SignedConstants;
+ const std::vector<std::tuple<uint64_t, std::string>> UnsignedConstants;
+ utils::IncludeInserter Inserter;
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USENUMERICLIMITSCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 6b8fe22242417..b2dfb0de6ae68 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -91,6 +91,11 @@ Improvements to clang-tidy
New checks
^^^^^^^^^^
+- New :doc:`readability-use-numeric-limits
+ <clang-tidy/checks/readability/use-numeric-limits>` check to replace certain
+ integer literals with ``std::numeric_limits`` calls.
+
+
New check aliases
^^^^^^^^^^^^^^^^^
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 7b9b905ef7671..e69ab96cf4bf9 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -403,6 +403,7 @@ Clang-Tidy Checks
:doc:`readability-uniqueptr-delete-release <readability/uniqueptr-delete-release>`, "Yes"
:doc:`readability-uppercase-literal-suffix <readability/uppercase-literal-suffix>`, "Yes"
:doc:`readability-use-anyofallof <readability/use-anyofallof>`,
+ :doc:`readability-use-numeric-limits <readability/use-numeric-limits>`, "Yes"
:doc:`readability-use-std-min-max <readability/use-std-min-max>`, "Yes"
:doc:`zircon-temporary-objects <zircon/temporary-objects>`,
diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability/use-numeric-limits.rst b/clang-tools-extra/docs/clang-tidy/checks/readability/use-numeric-limits.rst
new file mode 100644
index 0000000000000..ed50d00f1085d
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/readability/use-numeric-limits.rst
@@ -0,0 +1,22 @@
+.. title:: clang-tidy - readability-use-numeric-limits
+
+readability-use-numeric-limits
+==============================
+
+Replaces certain integer literals with ``std::numeric_limits`` calls.
+
+Before:
+
+.. code-block:: c++
+
+ void foo() {
+ int32_t a = 2147483647;
+ }
+
+After:
+
+.. code-block:: c++
+
+ void foo() {
+ int32_t a = std::numeric_limits<int32_t>::max();
+ }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/use-numeric-limits.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/use-numeric-limits.cpp
new file mode 100644
index 0000000000000..2f1d5190148b0
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/use-numeric-limits.cpp
@@ -0,0 +1,85 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s readability-use-numeric-limits %t
+#include <stdint.h>
+
+void constants() {
+ // 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]
+ // CHECK-FIXES: int8_t _ = std::numeric_limits<int8_t>::min();
+ int8_t _ = -128;
+
+ // 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]
+ // CHECK-FIXES: int8_t _ = std::numeric_limits<int8_t>::max();
+ int8_t _ = +127;
+
+ // 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]
+ // CHECK-FIXES: int8_t _ = std::numeric_limits<int8_t>::max();
+ int8_t _ = 127;
+
+ // 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]
+ // CHECK-FIXES: int16_t _ = std::numeric_limits<int16_t>::min();
+ int16_t _ = -32768;
+
+ // 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]
+ // CHECK-FIXES: int16_t _ = std::numeric_limits<int16_t>::max();
+ int16_t _ = +32767;
+
+ // 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]
+ // CHECK-FIXES: int16_t _ = std::numeric_limits<int16_t>::max();
+ int16_t _ = 32767;
+
+ // 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]
+ // CHECK-FIXES: int32_t _ = std::numeric_limits<int32_t>::min();
+ int32_t _ = -2147483648;
+
+ // 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]
+ // CHECK-FIXES: int32_t _ = std::numeric_limits<int32_t>::max();
+ int32_t _ = +2147483647;
+
+ // 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]
+ // CHECK-FIXES: int32_t _ = std::numeric_limits<int32_t>::max();
+ int32_t _ = 2147483647;
+
+ // 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]
+ // CHECK-FIXES: int64_t _ = std::numeric_limits<int64_t>::min();
+ int64_t _ = -9223372036854775808;
+
+ // 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]
+ // CHECK-FIXES: int64_t _ = std::numeric_limits<int64_t>::max();
+ int64_t _ = +9223372036854775807;
+
+ // 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]
+ // CHECK-FIXES: int64_t _ = std::numeric_limits<int64_t>::max();
+ int64_t _ = 9223372036854775807;
+
+ // 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]
+ // CHECK-FIXES: uint8_t _ = std::numeric_limits<uint8_t>::max();
+ uint8_t _ = 255;
+
+ // 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]
+ // CHECK-FIXES: uint8_t _ = std::numeric_limits<uint8_t>::max();
+ uint8_t _ = +255;
+
+ // 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]
+ // CHECK-FIXES: uint16_t _ = std::numeric_limits<uint16_t>::max();
+ uint16_t _ = 65535;
+
+ // 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]
+ // CHECK-FIXES: uint16_t _ = std::numeric_limits<uint16_t>::max();
+ uint16_t _ = +65535;
+
+ // 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]
+ // CHECK-FIXES: uint32_t _ = std::numeric_limits<uint32_t>::max();
+ uint32_t _ = 4294967295;
+
+ // 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]
+ // CHECK-FIXES: uint32_t _ = std::numeric_limits<uint32_t>::max();
+ uint32_t _ = +4294967295;
+
+ // 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]
+ // CHECK-FIXES: uint64_t _ = std::numeric_limits<uint64_t>::max();
+ uint64_t _ = 18446744073709551615;
+
+ // 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]
+ // CHECK-FIXES: uint64_t _ = std::numeric_limits<uint64_t>::max();
+ uint64_t _ = +18446744073709551615;
+}
+
``````````
</details>
https://github.com/llvm/llvm-project/pull/127430
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