'goto', as an indicator of good language

[Nick Treleaven]

On Thursday, 8 September 2022 at 22:47:33 UTC, Walter Bright 
wrote:
> To be fair, nested functions along with function inlining has 
> eliminated many of the reasons that I use gotos.
>
> Another reason for gotos is for ways of exiting loops without 
> having to set flags that later control the flow.

Yeah, there's this code from dmd/dsymbolsem.d:

```d
     if (FuncDeclaration func = sc.parent.isFuncDeclaration())
     {
         tm.symtab = func.localsymtab;
         if (tm.symtab)
         {
             // Inside template constraint, symtab is not set yet.
             goto L1;
         }
     }
     else
     {
         tm.symtab = sc.parent.isScopeDsymbol().symtab;
     L1:
         assert(tm.symtab);
         tm.ident = Identifier.generateId(s, tm.symtab.length + 1);
         tm.symtab.insert(tm);
     }
```
You can write it as:
```d
     (){
         if (FuncDeclaration func = sc.parent.isFuncDeclaration())
         {
             tm.symtab = func.localsymtab;
             if (!tm.symtab) return;
             // Inside template constraint, symtab is not set yet.
         }
         else
             tm.symtab = sc.parent.isScopeDsymbol().symtab;
     //L1:
         assert(tm.symtab);
         tm.ident = Identifier.generateId(s, tm.symtab.length + 1);
         tm.symtab.insert(tm);
     }();
```
I'd prefer to write it as:
```d
     switch
     {
         if (FuncDeclaration func = sc.parent.isFuncDeclaration())
         {
             tm.symtab = func.localsymtab;
             if (!tm.symtab) break;
             // Inside template constraint, symtab is not set yet.
         }
         else
             tm.symtab = sc.parent.isScopeDsymbol().symtab;
     //L1:
         assert(tm.symtab);
         tm.ident = Identifier.generateId(s, tm.symtab.length + 1);
         tm.symtab.insert(tm);
     }
```
Where `switch` works like `switch(0) default:` today.

Using the function literal call means you can't return from the 
containing function, which may be needed.