[clang-tools-extra] [clang-tidy] Create a check for signed and unsigned integers comparison (PR #113144)

[Julian Schmidt via cfe-commits]

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@@ -0,0 +1,165 @@
+//===--- UseIntegerSignComparisonCheck.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 "UseIntegerSignComparisonCheck.h"
+#include "clang/AST/Expr.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+using namespace clang::ast_matchers::internal;
+
+namespace clang::tidy::modernize {
+UseIntegerSignComparisonCheck::UseIntegerSignComparisonCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
+                                               utils::IncludeSorter::IS_LLVM),
+                      areDiagsSelfContained()),
+      IsQtApplication(Options.get("IsQtApplication", false)),
+      StringsMatchHeader(Options.get("StringsMatchHeader", "<utility>")) {}
+
+void UseIntegerSignComparisonCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IsQtApplication", IsQtApplication);
+  Options.store(Opts, "StringsMatchHeader", StringsMatchHeader);
+}
+
+void UseIntegerSignComparisonCheck::registerMatchers(MatchFinder *Finder) {
+  const auto SignedIntCastExpr = intCastExpression(true, "sIntCastExpression");
+  const auto UnSignedIntCastExpr =
+      intCastExpression(false, "uIntCastExpression");
+
+  // Flag all operators "==", "<=", ">=", "<", ">", "!="
+  // that are used between signed/unsigned
+  const auto CompareOperator =
+      expr(binaryOperator(hasAnyOperatorName("==", "<=", ">=", "<", ">", "!="),
+                          anyOf(allOf(hasLHS(SignedIntCastExpr),
+                                      hasRHS(UnSignedIntCastExpr)),
+                                allOf(hasLHS(UnSignedIntCastExpr),
+                                      hasRHS(SignedIntCastExpr)))))
+          .bind("intComparison");
+
+  Finder->addMatcher(CompareOperator, this);
+}
+
+BindableMatcher<clang::Stmt> UseIntegerSignComparisonCheck::intCastExpression(
+    bool IsSigned, const std::string &CastBindName) const {
+  auto IntTypeExpr = expr();
+  if (IsSigned) {
+    IntTypeExpr = expr(hasType(qualType(isInteger(), isSignedInteger())));
+  } else {
+    IntTypeExpr =
+        expr(hasType(qualType(isInteger(), unless(isSignedInteger()))));
+  }
+
+  const auto ImplicitCastExpr =
+      implicitCastExpr(hasSourceExpression(IntTypeExpr)).bind(CastBindName);
+
+  const auto CStyleCastExpr = cStyleCastExpr(has(ImplicitCastExpr));
+  const auto StaticCastExpr = cxxStaticCastExpr(has(ImplicitCastExpr));
+  const auto FunctionalCastExpr = cxxFunctionalCastExpr(has(ImplicitCastExpr));
+
+  return traverse(TK_AsIs, expr(anyOf(ImplicitCastExpr, CStyleCastExpr,
+                                      StaticCastExpr, FunctionalCastExpr)));
----------------
5chmidti wrote:

This `traverse` has no effect, as the default traversal is already `AsIs` traversal.

https://github.com/llvm/llvm-project/pull/113144