[clang-tools-extra] [clang-tidy] bugprone-assert-side-effect non-const operator methods (PR #71974)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-tidy

Author: None (schenker)

<details>
<summary>Changes</summary>

With this PR, `bugprone-assert-side-effect` assumes that operator methods that are not marked as `const` have side effects. This matches the existing rule for non-operator methods.

E.g. the following snippet is now reported and was previously not:
```
std::stringstream ss;
assert(ss << 1);
```

---
Full diff: https://github.com/llvm/llvm-project/pull/71974.diff


2 Files Affected:

- (modified) clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp (+4) 
- (modified) clang-tools-extra/test/clang-tidy/checkers/bugprone/assert-side-effect.cpp (+12-1) 


``````````diff
diff --git a/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
index 07a987359d4d8d7..599f5ac70e7a229 100644
--- a/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/AssertSideEffectCheck.cpp
@@ -41,6 +41,10 @@ AST_MATCHER_P2(Expr, hasSideEffect, bool, CheckFunctionCalls,
   }
 
   if (const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
+    if (const auto *FuncDecl = OpCallExpr->getDirectCallee())
+      if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
+        return !MethodDecl->isConst();
+
     OverloadedOperatorKind OpKind = OpCallExpr->getOperator();
     return OpKind == OO_Equal || OpKind == OO_PlusEqual ||
            OpKind == OO_MinusEqual || OpKind == OO_StarEqual ||
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/assert-side-effect.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/assert-side-effect.cpp
index 6c41e1e320adeac..49d3d456deb9d35 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/assert-side-effect.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/assert-side-effect.cpp
@@ -11,7 +11,7 @@ class MyClass {
 
   MyClass &operator=(const MyClass &rhs) { return *this; }
 
-  int operator-() { return 1; }
+  int operator-() const { return 1; }
 
   operator bool() const { return true; }
 
@@ -84,5 +84,16 @@ int main() {
   msvc_assert(mc2 = mc);
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: side effect in msvc_assert() condition discarded in release builds
 
+  struct {
+    int operator<<(int i) const { return i; }
+  } constOp;
+  assert(constOp << 1);
+
+  struct {
+    int operator<<(int i) { return i; }
+  } nonConstOp;
+  assert(nonConstOp << 1);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: side effect in assert() condition discarded in release builds
+
   return 0;
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/71974