[clang-tidy]bugprone-unused-return-value ignore `++` and `--` operator overloading (#84922)

Fixes: #84705
Further fix for #84489

2 files changed, 57 insertions, 29 deletions

diff --git a/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
index 243fe47..7337314 100644
--- a/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
@@ -31,9 +31,16 @@ AST_MATCHER_P(FunctionDecl, isInstantiatedFrom, Matcher<FunctionDecl>,
                               Finder, Builder);
 }
 
-AST_MATCHER_P(CXXMethodDecl, isOperatorOverloading,
-              llvm::SmallVector<OverloadedOperatorKind>, Kinds) {
-  return llvm::is_contained(Kinds, Node.getOverloadedOperator());
+constexpr std::initializer_list<OverloadedOperatorKind>
+    AssignmentOverloadedOperatorKinds = {
+        OO_Equal,      OO_PlusEqual,     OO_MinusEqual,          OO_StarEqual,
+        OO_SlashEqual, OO_PercentEqual,  OO_CaretEqual,          OO_AmpEqual,
+        OO_PipeEqual,  OO_LessLessEqual, OO_GreaterGreaterEqual, OO_PlusPlus,
+        OO_MinusMinus};
+
+AST_MATCHER(FunctionDecl, isAssignmentOverloadedOperator) {
+  return llvm::is_contained(AssignmentOverloadedOperatorKinds,
+                            Node.getOverloadedOperator());
 }
 } // namespace
 
@@ -164,22 +171,18 @@ void UnusedReturnValueCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
 }
 
 void UnusedReturnValueCheck::registerMatchers(MatchFinder *Finder) {
-  auto MatchedDirectCallExpr = expr(
-      callExpr(
-          callee(functionDecl(
-              // Don't match void overloads of checked functions.
-              unless(returns(voidType())),
-              // Don't match copy or move assignment operator.
-              unless(cxxMethodDecl(isOperatorOverloading(
-                  {OO_Equal, OO_PlusEqual, OO_MinusEqual, OO_StarEqual,
-                   OO_SlashEqual, OO_PercentEqual, OO_CaretEqual, OO_AmpEqual,
-                   OO_PipeEqual, OO_LessLessEqual, OO_GreaterGreaterEqual}))),
-              anyOf(
-                  isInstantiatedFrom(
-                      matchers::matchesAnyListedName(CheckedFunctions)),
-                  returns(hasCanonicalType(hasDeclaration(namedDecl(
-                      matchers::matchesAnyListedName(CheckedReturnTypes)))))))))
-          .bind("match"));
+  auto MatchedDirectCallExpr =
+      expr(callExpr(callee(functionDecl(
+                        // Don't match copy or move assignment operator.
+                        unless(isAssignmentOverloadedOperator()),
+                        // Don't match void overloads of checked functions.
+                        unless(returns(voidType())),
+                        anyOf(isInstantiatedFrom(matchers::matchesAnyListedName(
+                                  CheckedFunctions)),
+                              returns(hasCanonicalType(hasDeclaration(
+                                  namedDecl(matchers::matchesAnyListedName(
+                                      CheckedReturnTypes)))))))))
+               .bind("match"));
 
   auto CheckCastToVoid =
       AllowCastToVoid ? castExpr(unless(hasCastKind(CK_ToVoid))) : castExpr();
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-return-value-avoid-assignment.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-return-value-avoid-assignment.cpp
index b4a4100..564c07a 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-return-value-avoid-assignment.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-return-value-avoid-assignment.cpp
@@ -3,23 +3,37 @@
 // RUN:  {bugprone-unused-return-value.CheckedFunctions: "::*"}}' \
 // RUN: --
 
-struct S {
-  S(){};
-  S(S const &);
-  S(S &&);
-  S &operator=(S const &);
-  S &operator=(S &&);
-  S &operator+=(S);
+struct S1 {
+  S1(){};
+  S1(S1 const &);
+  S1(S1 &&);
+  S1 &operator=(S1 const &);
+  S1 &operator=(S1 &&);
+  S1 &operator+=(S1);
+  S1 &operator++();
+  S1 &operator++(int);
+  S1 &operator--();
+  S1 &operator--(int);
 };
 
-S returnValue();
-S const &returnRef();
+struct S2 {
+  S2(){};
+  S2(S2 const &);
+  S2(S2 &&);
+};
+
+S2 &operator-=(S2&, int);
+S2 &operator++(S2 &);
+S2 &operator++(S2 &, int);
+
+S1 returnValue();
+S1 const &returnRef();
 
 void bar() {
   returnValue();
   // CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
 
-  S a{};
+  S1 a{};
   a = returnValue();
   a.operator=(returnValue());
 
@@ -27,4 +41,15 @@ void bar() {
   a.operator=(returnRef());
 
   a += returnRef();
+
+  a++;
+  ++a;
+  a--;
+  --a;
+
+  S2 b{};
+
+  b -= 1;
+  b++;
+  ++b;
 }