[clang-tidy] Clarify diagnostics of bugprone-sizeof-expression

clang-tools-extra/clang-tidy/bugprone/SizeofExpressionCheck.cpp

@@ -296,7 +296,7 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
   } else if (const auto *E =
                  Result.Nodes.getNodeAs<Expr>("sizeof-integer-call")) {
     diag(E->getBeginLoc(), "suspicious usage of 'sizeof()' on an expression "
-                           "that results in an integer")
+                           "of integer type")
         << E->getSourceRange();
   } else if (const auto *E = Result.Nodes.getNodeAs<Expr>("sizeof-this")) {
     diag(E->getBeginLoc(),
@@ -314,7 +314,7 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
           << E->getSourceRange();
     } else {
       diag(E->getBeginLoc(), "suspicious usage of 'sizeof()' on an expression "
-                             "that results in a pointer")
+                             "of pointer type")
           << E->getSourceRange();
     }
   } else if (const auto *E = Result.Nodes.getNodeAs<BinaryOperator>(
@@ -348,25 +348,28 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
     } else if (ElementSize > CharUnits::Zero() &&
                DenominatorSize > CharUnits::Zero() &&
                ElementSize != DenominatorSize) {
-      diag(E->getOperatorLoc(), "suspicious usage of 'sizeof(...)/sizeof(...)';"
-                                " numerator is not a multiple of denominator")
+      // FIXME: Apparently there are no testcases that cover this branch!
+      diag(E->getOperatorLoc(),
+           "suspicious usage of 'sizeof(array)/sizeof(...)';"
+           " denominator differs from the size of array elements")
           << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
     } else if (NumTy && DenomTy && NumTy == DenomTy) {
-      // FIXME: This message is wrong, it should not refer to sizeof "pointer"
-      // usage (and by the way, it would be to clarify all the messages).
       diag(E->getOperatorLoc(),
-           "suspicious usage of sizeof pointer 'sizeof(T)/sizeof(T)'")
+           "suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions "
+           "have the same type")
           << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
     } else if (!WarnOnSizeOfPointer) {
       // When 'WarnOnSizeOfPointer' is enabled, these messages become redundant:
       if (PointedTy && DenomTy && PointedTy == DenomTy) {
         diag(E->getOperatorLoc(),
-             "suspicious usage of sizeof pointer 'sizeof(T*)/sizeof(T)'")
+             "suspicious usage of 'sizeof(...)/sizeof(...)'; size of pointer "
+             "is divided by size of pointed type")
             << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
       } else if (NumTy && DenomTy && NumTy->isPointerType() &&
                  DenomTy->isPointerType()) {
         diag(E->getOperatorLoc(),
-             "suspicious usage of sizeof pointer 'sizeof(P*)/sizeof(Q*)'")
+             "suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions "
+             "have pointer types")
             << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
       }
     }

clang-tools-extra/docs/ReleaseNotes.rst

@@ -238,10 +238,10 @@ Changes in existing checks
   false positives resulting from use of optionals in unevaluated context.
 
 - Improved :doc:`bugprone-sizeof-expression
-  <clang-tidy/checks/bugprone/sizeof-expression>` check by eliminating some
-  false positives and adding a new (off-by-default) option
-  `WarnOnSizeOfPointer` that reports all ``sizeof(pointer)`` expressions
-  (except for a few that are idiomatic).
+  <clang-tidy/checks/bugprone/sizeof-expression>` check by clarifying the
+  diagnostics, eliminating some false positives and adding a new
+  (off-by-default) option `WarnOnSizeOfPointer` that reports all
+  ``sizeof(pointer)`` expressions (except for a few that are idiomatic).
 
 - Improved :doc:`bugprone-suspicious-include
   <clang-tidy/checks/bugprone/suspicious-include>` check by replacing the local

clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression-2.c

@@ -34,24 +34,24 @@ int Test5() {
 
   int sum = 0;
   sum += sizeof(&S);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(__typeof(&S));
   sum += sizeof(&TS);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(__typeof(&TS));
   sum += sizeof(STRKWD MyStruct*);
   sum += sizeof(__typeof(STRKWD MyStruct*));
   sum += sizeof(TypedefStruct*);
   sum += sizeof(__typeof(TypedefStruct*));
   sum += sizeof(PTTS);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PMyStruct);
   sum += sizeof(PS);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PS2);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(&A10);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
 
 #ifdef __cplusplus
   MyStruct &rS = S;

clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression-any-pointer.cpp

@@ -38,17 +38,17 @@ int Test1(const char* ptr) {
   sum += sizeof(sum, LEN);
   // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: suspicious usage of 'sizeof(..., ...)'
   sum += sizeof(AsBool());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(AsInt());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(AsEnum());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(AsEnumClass());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(M{}.AsInt());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(M{}.AsEnum());
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in an integer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of integer type
   sum += sizeof(sizeof(X));
   // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(sizeof(...))'
   sum += sizeof(LEN + sizeof(X));
@@ -62,7 +62,7 @@ int Test1(const char* ptr) {
   sum += sizeof(LEN + - + -sizeof(X));
   // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(sizeof(...))'
   sum += sizeof(char) / sizeof(char);
-  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: suspicious usage of sizeof pointer 'sizeof(T)/sizeof(T)'
+  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions have the same type
   sum += sizeof(A) / sizeof(S);
   // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; numerator is not a multiple of denominator
   sum += sizeof(char) / sizeof(int);
@@ -72,21 +72,21 @@ int Test1(const char* ptr) {
   sum += sizeof(B[0]) / sizeof(A);
   // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; numerator is not a multiple of denominator
   sum += sizeof(ptr) / sizeof(char);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(ptr) / sizeof(ptr[0]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(ptr) / sizeof(char*);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(ptr) / sizeof(void*);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(ptr) / sizeof(const void volatile*);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(ptr) / sizeof(char);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(int) * sizeof(char);
   // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: suspicious 'sizeof' by 'sizeof' multiplication
   sum += sizeof(ptr) * sizeof(ptr[0]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   // CHECK-MESSAGES: :[[@LINE-2]]:22: warning: suspicious 'sizeof' by 'sizeof' multiplication
   sum += sizeof(int) * (2 * sizeof(char));
   // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: suspicious 'sizeof' by 'sizeof' multiplication
@@ -127,54 +127,54 @@ int Test5() {
 
   int sum = 0;
   sum += sizeof(&S.arr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(&kGlocalMyStruct.arr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(&kGlocalMyStructPtr->arr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(S.arr + 0);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(+ S.arr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof((int*)S.arr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
 
   sum += sizeof(S.ptr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(kGlocalMyStruct.ptr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(kGlocalMyStructPtr->ptr);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
 
   sum += sizeof(&kGlocalMyStruct);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(&S);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(MyStruct*);
   sum += sizeof(PMyStruct);
   sum += sizeof(PS);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PS2);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(&A10);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PtrArray) / sizeof(PtrArray[1]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:29: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(A10) / sizeof(PtrArray[0]);
   sum += sizeof(PC) / sizeof(PtrArray[0]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
-  // CHECK-MESSAGES: :[[@LINE-2]]:21: warning: suspicious usage of sizeof pointer 'sizeof(T)/sizeof(T)'
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
+  // CHECK-MESSAGES: :[[@LINE-2]]:21: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions have the same type
   sum += sizeof(ArrayC) / sizeof(PtrArray[0]);
   // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; numerator is not a multiple of denominator
 
   sum += sizeof(PChar);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PInt);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PPInt);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(PPMyStruct);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
 
   return sum;
 }
@@ -200,9 +200,9 @@ void GenericFunctionTest() {
   // reported by the `sizeof(pointer)` checks, but this causes some false
   // positives, so it would be good to create an exception for them.
   some_generic_function(&IntPP, sizeof(IntP));
-  // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:33: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   some_generic_function(&ClassPP, sizeof(ClassP));
-  // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:35: warning: suspicious usage of 'sizeof()' on an expression of pointer type
 }
 
 int ValidExpressions() {
@@ -222,7 +222,7 @@ int ValidExpressions() {
   sum += sizeof(A[sizeof(A) / sizeof(int)]);
   // Here the outer sizeof is reported, but the inner ones are accepted:
   sum += sizeof(&A[sizeof(A) / sizeof(int)]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression that results in a pointer
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof()' on an expression of pointer type
   sum += sizeof(sizeof(0));  // Special case: sizeof size_t.
   sum += sizeof(void*);
   sum += sizeof(void const *);

clang-tools-extra/test/clang-tidy/checkers/bugprone/sizeof-expression-warn-on-sizeof-pointer-to-aggregate.cpp

@@ -68,7 +68,7 @@ int Test5() {
   sum += sizeof(A10) / sizeof(PtrArray[0]);
   // No warning.
   sum += sizeof(PC) / sizeof(PtrArray[0]);
-  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: suspicious usage of sizeof pointer 'sizeof(T)/sizeof(T)'
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; both expressions have the same type
   sum += sizeof(ArrayC) / sizeof(PtrArray[0]);
   // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: suspicious usage of 'sizeof(...)/sizeof(...)'; numerator is not a multiple of denominator