Add option to allow pre/post increment/decrement operator in cppcoreg… (llvm#155015)

…uidelines-pro-bounds-pointer-arithmetic

Fixes llvm#154907

Co-authored-by: Carlos Gálvez <[email protected]>

Author: carlosgalvezp

clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp

@@ -14,6 +14,18 @@ using namespace clang::ast_matchers;
 
 namespace clang::tidy::cppcoreguidelines {
 
+ProBoundsPointerArithmeticCheck::ProBoundsPointerArithmeticCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      AllowIncrementDecrementOperators(
+          Options.get("AllowIncrementDecrementOperators", false)) {}
+
+void ProBoundsPointerArithmeticCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "AllowIncrementDecrementOperators",
+                AllowIncrementDecrementOperators);
+}
+
 void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
   const auto AllPointerTypes =
       anyOf(hasType(hasUnqualifiedDesugaredType(pointerType())),
@@ -30,13 +42,14 @@ void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
       this);
 
   // Flag all operators ++, -- that result in a pointer
-  Finder->addMatcher(
-      unaryOperator(hasAnyOperatorName("++", "--"),
-                    hasType(hasUnqualifiedDesugaredType(pointerType())),
-                    unless(hasUnaryOperand(
-                        ignoringImpCasts(declRefExpr(to(isImplicit()))))))
-          .bind("expr"),
-      this);
+  if (!AllowIncrementDecrementOperators)
+    Finder->addMatcher(
+        unaryOperator(hasAnyOperatorName("++", "--"),
+                      hasType(hasUnqualifiedDesugaredType(pointerType())),
+                      unless(hasUnaryOperand(
+                          ignoringImpCasts(declRefExpr(to(isImplicit()))))))
+            .bind("expr"),
+        this);
 
   // Array subscript on a pointer (not an array) is also pointer arithmetic
   Finder->addMatcher(

clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.h

@@ -21,13 +21,16 @@ namespace clang::tidy::cppcoreguidelines {
 /// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/pro-bounds-pointer-arithmetic.html
 class ProBoundsPointerArithmeticCheck : public ClangTidyCheck {
 public:
-  ProBoundsPointerArithmeticCheck(StringRef Name, ClangTidyContext *Context)
-      : ClangTidyCheck(Name, Context) {}
+  ProBoundsPointerArithmeticCheck(StringRef Name, ClangTidyContext *Context);
   bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
     return LangOpts.CPlusPlus;
   }
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  const bool AllowIncrementDecrementOperators;
 };
 
 } // namespace clang::tidy::cppcoreguidelines

clang-tools-extra/docs/ReleaseNotes.rst

@@ -180,6 +180,11 @@ Changes in existing checks
   <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check to
   avoid false positives on inherited members in class templates.
 
+- Improved :doc:`cppcoreguidelines-pro-bounds-pointer-arithmetic
+  <clang-tidy/checks/cppcoreguidelines/pro-bounds-pointer-arithmetic>` check
+  adding an option to allow pointer arithmetic via prefix/postfix increment or
+  decrement operators.
+
 - Improved :doc:`misc-header-include-cycle
   <clang-tidy/checks/misc/header-include-cycle>` check performance.
 

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-bounds-pointer-arithmetic.rst

@@ -13,3 +13,11 @@ arrays of data.
 This rule is part of the `Bounds safety (Bounds 1)
 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Pro-bounds-arithmetic>`_
 profile from the C++ Core Guidelines.
+
+Options
+-------
+
+.. option:: AllowIncrementDecrementOperators
+
+   When enabled, the check will allow using the prefix/postfix increment or
+   decrement operators on pointers. Default is ``false``.

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-bounds-pointer-arithmetic.cpp

@@ -1,4 +1,6 @@
-// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic -check-suffixes=,DEFAULT  %t
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t -- \
+// RUN:   -config="{CheckOptions: {cppcoreguidelines-pro-bounds-pointer-arithmetic.AllowIncrementDecrementOperators: true}}" --
 
 enum E {
   ENUM_LITERAL = 1
@@ -42,22 +44,22 @@ void fail() {
   // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not use pointer arithmetic
 
   p++;
-  // CHECK-MESSAGES: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
   ++p;
-  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:3: warning: do not use pointer arithmetic
 
   p--;
-  // CHECK-MESSAGES: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
   --p;
-  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:3: warning: do not use pointer arithmetic
 
   i = p[1];
   // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use pointer arithmetic
 
   p = ip + 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: do not use pointer arithmetic
   ip++;
-  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:5: warning: do not use pointer arithmetic
   i = ip[1];
   // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use pointer arithmetic
 }
@@ -72,7 +74,7 @@ void template_fail() {
   q = p - 1;
   // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: do not use pointer arithmetic
   p++;
-  // CHECK-MESSAGES: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
+  // CHECK-MESSAGES-DEFAULT: :[[@LINE-1]]:4: warning: do not use pointer arithmetic
   i = p[1];
   // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: do not use pointer arithmetic
 }