[clang-tools-extra] [clang-tidy] Add new check `readability-use-numeric-limits` (PR #127430)

[via cfe-commits]

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@@ -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();
----------------
EugeneZelenko wrote:

Please do not use `auto` unless type is explicitly stated in same statement or iterator.

https://github.com/llvm/llvm-project/pull/127430