[Sema][NFC] add check before using `BuildExpressionFromIntegralTemplateArgument`

[HerrCai0907]

Summary

This patch wants to avoid Sema crash for inline friend decl like

template <class F1> int foo(F1 X);
template <int A1> struct A {
  template <class F1> friend int foo(F1 X) { return A1; }
};

template struct A<1>;
int a = foo(1.0);

But this case is still not fixed

[erichkeane]

This is the wrong fix here, the crash is appropriate here, else we're not getting the type right. For your example, we need to be setting up the template arguments correctly.

[erichkeane]

See my comment on https://github.com/llvm/llvm-project/issues/62265 for results of my debugging.

clang/lib/Sema/SemaTemplateInstantiate.cpp

if (arg.getKind() == TemplateArgument::Declaration) {
       VD = nullptr;
     }
 
     QualType paramType = VD ? arg.getParamTypeForDecl() : arg.getNullPtrType();
     assert(!paramType.isNull() && "type substitution failed for param type");
     assert(!paramType->isDependentType() && "param type still dependent");
     result = SemaRef.BuildExpressionFromDeclTemplateArgument(arg, paramType, loc);
     refParam = paramType->isReferenceType();
-  } else {
+  } else if (arg.getKind() == TemplateArgument::Integral) {
     result = SemaRef.BuildExpressionFromIntegralTemplateArgument(arg, loc);
     assert(result.isInvalid() ||
            SemaRef.Context.hasSameType(result.get()->getType(),
                                        arg.getIntegralType()));
   }
 
   if (result.isInvalid())
     return ExprError();