Do it properly, also add release notes

Author: localspook

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

@@ -378,7 +378,7 @@ void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
     if (const auto *Type = dyn_cast<ArrayType>(SizeofArgTy)) {
       // check if the array element size is larger than one. If true,
       // the size of the array is higher than the number of elements
-      if (!getSizeOfType(Ctx, Type).isOne()) {
+      if (!getSizeOfType(Ctx, Type->getElementType().getTypePtr()).isOne()) {
         diag(SzOfExpr->getBeginLoc(),
              "suspicious usage of 'sizeof' in the loop")
             << SzOfExpr->getSourceRange();

clang-tools-extra/docs/ReleaseNotes.rst

@@ -231,6 +231,10 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/signed-char-misuse>` check by fixing
   false positives on C23 enums with the fixed underlying type of signed char.
 
+- Improved :doc:`bugprone-sizeof-expression
+  <clang-tidy/checks/bugprone/sizeof-expression>` check by fixing
+  a crash on ``sizeof`` of an array of template type.
+
 - Improved :doc:`bugprone-tagged-union-member-count
   <clang-tidy/checks/bugprone/tagged-union-member-count>` by fixing a false
   positive when enums or unions from system header files or the ``std``