[clang-tidy] Fix false positive in misc-const-correctness

clang-tools-extra/docs/ReleaseNotes.rst

@@ -69,7 +69,7 @@ Potentially Breaking Changes
   - `CharTypdefsToIgnore` to `CharTypedefsToIgnore` in
     :doc:`bugprone-signed-char-misuse
     <clang-tidy/checks/bugprone/signed-char-misuse>`
-  
+
 - Modified the custom message format of :doc:`bugprone-unsafe-functions
   <clang-tidy/checks/bugprone/unsafe-functions>` by assigning a special meaning
   to the character ``>`` at the start of the value of the option
@@ -394,7 +394,7 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/unhandled-self-assignment>` check by adding
   an additional matcher that generalizes the copy-and-swap idiom pattern
   detection.
-  
+
 - Improved :doc:`bugprone-unsafe-functions
   <clang-tidy/checks/bugprone/unsafe-functions>` check by hiding the default
   suffix when the reason starts with the character `>` in the `CustomFunctions`
@@ -447,7 +447,8 @@ Changes in existing checks
   positives when pointers is transferred to non-const references
   and avoid false positives of function pointer and fix false
   positives on return of non-const pointer and fix false positives on
-  pointer-to-member operator.
+  pointer-to-member operator and avoid false positives when the address
+  of a variable is taken to be passed to a function.
 
 - Improved :doc:`misc-coroutine-hostile-raii
   <clang-tidy/checks/misc/coroutine-hostile-raii>` check by adding the option

clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-pointer-as-pointers.cpp

@@ -73,3 +73,18 @@ void ignoreNonConstRefOps() {
   int* p2 {nullptr};
   int*& r2 = (int*&)p2;
 }
+
+void pointer_to_pointer_param(int**);
+void pass_address_to_pointer_to_pointer() {
+  int i = 0;
+  int* ip = &i;
+  // CHECK-NOT: warning
+  pointer_to_pointer_param(&ip);
+}
+
+void void_pointer_to_pointer_param(void**);
+void pass_address_to_void_pointer_to_pointer() {
+  void* ptr = nullptr;
+  // CHECK-NOT: warning
+  void_pointer_to_pointer_param(&ptr);
+}

clang/lib/Analysis/ExprMutationAnalyzer.cpp

@@ -135,6 +135,11 @@ class ExprPointeeResolve {
     if (const auto *PE = dyn_cast<ParenExpr>(E))
       return resolveExpr(PE->getSubExpr());
 
+    if (const auto *UO = dyn_cast<UnaryOperator>(E)) {
+      if (UO->getOpcode() == UO_AddrOf)
+        return resolveExpr(UO->getSubExpr());
+    }
+
     if (const auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
       // only implicit cast needs to be treated as resolvable.
       // explicit cast will be checked in `findPointeeToNonConst`

clang/unittests/Analysis/ExprMutationAnalyzerTest.cpp

@@ -2091,4 +2091,21 @@ TEST(ExprMutationAnalyzerTest, PointeeMutatedByPointerToMemberOperator) {
   EXPECT_TRUE(isPointeeMutated(Results, AST.get()));
 }
 
+TEST(ExprMutationAnalyzerTest, PointeeMutatedByPassAsPointerToPointer) {
+  {
+    const std::string Code = "void f(int**); void g() { int* ip; f(&ip); }";
+    auto AST = buildASTFromCode(Code);
+    auto Results =
+        match(withEnclosingCompound(declRefTo("ip")), AST->getASTContext());
+    EXPECT_TRUE(isPointeeMutated(Results, AST.get()));
+  }
+  {
+    const std::string Code = "void f(void**); void g() { void* ip; f(&ip); }";
+    auto AST = buildASTFromCode(Code);
+    auto Results =
+        match(withEnclosingCompound(declRefTo("ip")), AST->getASTContext());
+    EXPECT_TRUE(isPointeeMutated(Results, AST.get()));
+  }
+}
+
 } // namespace clang