[cling] Able to call function with failing `static_assert` on second try

[hahnjo]

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Description

ROOT::Experimental::RHistEngine<BinContentType>::Scale(double) must not be called for integral bin content types. This is enforced with a static_assert, but it is still possible to call the function when retrying.

Reproducer

root [0] ROOT::Experimental::RHistEngine<int> hist(10, {5.0, 15.0});
root [1] hist.Scale(1);
In module 'ROOTHist':
/home/jhahnfel/ROOT/build-asserts-clang/include/ROOT/RHistEngine.hxx:486:21: error: static assertion failed due to requirement '!std::is_integral_v<int>': scaling is not supported for integral bin content types
      static_assert(!std::is_integral_v<BinContentType>, "scaling is not supported for integral bin content types");
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ROOT_prompt_1:1:6: note: in instantiation of member function 'ROOT::Experimental::RHistEngine<int>::Scale' requested here
hist.Scale(1);
     ^
root [2] hist.Scale(1);
root [3]

ROOT version

master

Installation method

from source

Operating system

Linux

Additional context

The (possible) reason is that Scale is a non-templated method in the templated class RHistEngine. During unloading, we probably only take care of entire templated classes and templated methods (?).

[hahnjo]

Attempts to reproduce in a standalone example didn't work when I first discovered the issue in November:

root [1] template <typename T> struct S { void Scale(double) { static_assert(!std::is_integral_v<T>); } };
root [2] S<int> s;
root [3] s.Scale(0.8);
ROOT_prompt_1:1:69: error: static assertion failed due to requirement '!std::is_integral_v<int>'
template <typename T> struct S { void Scale(double) { static_assert(!std::is_integral_v<T>); } };
                                                                    ^~~~~~~~~~~~~~~~~~~~~~
ROOT_prompt_3:1:3: note: in instantiation of member function 'S<int>::Scale' requested here
s.Scale(0.8);
  ^
root [4] s.Scale(0.8);
ROOT_prompt_1:1:69: error: static assertion failed due to requirement '!std::is_integral_v<int>'
template <typename T> struct S { void Scale(double) { static_assert(!std::is_integral_v<T>); } };
                                                                    ^~~~~~~~~~~~~~~~~~~~~~
ROOT_prompt_4:1:3: note: in instantiation of member function 'S<int>::Scale' requested here
s.Scale(0.8);
  ^

It may be that modules and deserialization are somehow involved here...