[clang-tidy] Provide fix-its for casts to void* in google-readability-casting (#167655)

Author: ckandeler

clang-tools-extra/clang-tidy/google/AvoidCStyleCastsCheck.cpp

@@ -248,6 +248,12 @@ void AvoidCStyleCastsCheck::check(const MatchFinder::MatchResult &Result) {
       }
       break;
     }
+    if (DestType->isVoidPointerType() && SourceType->isPointerType() &&
+        !SourceType->getPointeeType()->isPointerType()) {
+      ReplaceWithNamedCast("reinterpret_cast");
+      return;
+    }
+
     [[fallthrough]];
   case clang::CK_IntegralCast:
     // Convert integral and no-op casts between builtin types and enums to

clang-tools-extra/docs/ReleaseNotes.rst

@@ -426,7 +426,7 @@ Changes in existing checks
 
 - Improved :doc:`google-readability-casting
   <clang-tidy/checks/google/readability-casting>` check by adding fix-it
-  notes for downcasts.
+  notes for downcasts and casts to void pointer.
 
 - Improved :doc:`google-readability-todo
   <clang-tidy/checks/google/readability-todo>` check to accept the new TODO

clang-tools-extra/test/clang-tidy/checkers/google/readability-casting.cpp

@@ -108,6 +108,10 @@ void f(int a, double b, const char *cpc, const void *cpv, X *pX) {
   // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: {{.*}}; use static_cast {{.*}}
   // CHECK-FIXES: Y &rB = static_cast<Y&>(*pX);
 
+  void *vp = (void *) pX;
+  // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: {{.*}}; use reinterpret_cast
+  // CHECK-FIXES: void *vp = reinterpret_cast<void *>(pX);
+
   const char *pc3 = (const char*)cpv;
   // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: {{.*}}; use static_cast [
   // CHECK-FIXES: const char *pc3 = static_cast<const char*>(cpv);