[Diagnostics] Fixed -Wsizeof-array-div false positive when divisor is sizeof reference type (PR47495)

Author: davidbolvansky

clang/lib/Sema/SemaExpr.cpp

@@ -10038,7 +10038,7 @@ static void DiagnoseDivisionSizeofPointerOrArray(Sema &S, Expr *LHS, Expr *RHS,
     QualType ArrayElemTy = ArrayTy->getElementType();
     if (ArrayElemTy != S.Context.getBaseElementType(ArrayTy) ||
         ArrayElemTy->isDependentType() || RHSTy->isDependentType() ||
-        ArrayElemTy->isCharType() ||
+        RHSTy->isReferenceType() || ArrayElemTy->isCharType() ||
         S.Context.getTypeSize(ArrayElemTy) == S.Context.getTypeSize(RHSTy))
       return;
     S.Diag(Loc, diag::warn_division_sizeof_array)

clang/test/Sema/div-sizeof-array.cpp

@@ -42,4 +42,8 @@ void test(void) {
 
   float m[4][4];
   int d1 = sizeof(m) / sizeof(**m);
+
+  int array[10];
+  int narray = sizeof(array) / sizeof(int &);
+  int narray2 = sizeof(array) / sizeof(decltype(array[0]));
 }