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

Author: ckandeler

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

@@ -157,6 +157,12 @@ void AvoidCStyleCastsCheck::check(const MatchFinder::MatchResult &Result) {
           << FixItHint::CreateRemoval(ReplaceRange);
       return;
     }
+    if (DestType->isVoidPointerType() && SourceType->isPointerType() &&
+        !SourceType->getPointeeType()->isPointerType()) {
+      diag(CastExpr->getBeginLoc(), "redundant cast to void *")
+          << FixItHint::CreateRemoval(ReplaceRange);
+      return;
+    }
   }
 
   // The rest of this check is only relevant to C++.

clang-tools-extra/docs/ReleaseNotes.rst

@@ -1,4 +1,4 @@
-.. If you want to modify sections/contents permanently, you should modify both
+#.. If you want to modify sections/contents permanently, you should modify both
    ReleaseNotes.rst and ReleaseNotesTemplate.txt.
 
 ====================================================
@@ -404,7 +404,7 @@ 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:`llvm-prefer-isa-or-dyn-cast-in-conditionals
   <clang-tidy/checks/llvm/prefer-isa-or-dyn-cast-in-conditionals>` check:

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: redundant cast
+  // CHECK-FIXES: void *vp = 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);