From: cr88192@gmail.com   
      
   On 11/5/2025 9:26 AM, Niklas Holsti wrote:   
   > On 2025-11-05 7:17, Anton Ertl wrote:   
   >   
   >     [ snip ]   
   >   
   >> Yes, assigned goto and labels-as-values (and probably the Cobol   
   >> alter/goto and PL/1 label variables) are there because computer   
   >> architectures have indirect branches and the programming language   
   >> designer wanted to give the programmers a way to express what they   
   >> would otherwise have to express in assembly language.   
   >>   
   >> Why does standard C not have it?  C had it up to and including the 6th   
   >> edition Unix <3714DA77.6150C99A@bell-labs.com>, but it went away   
   >> between 6th and 7th edition.  Ritchie wrote   
   >> <37178013.A1EE3D4F@bell-labs.com>:   
   >>   
   >> | I eliminated them because I didn't know what to say about their   
   >> | semantics.   
   >>   
   >> Stallman obviously knew what to say about their semantics when he   
   >> added labels-as-values to GNU C with gcc 2.0.   
   >   
   >   
   > I don't know what Stallman said, or would have said if asked, but I   
   > guess something like "the semantics is a jump to the (address of the)   
   > label to which the value refers", which is machine-level semantics and   
   > not semantics in the abstract C machine.   
   >   
   > The problem in the abstract C machine is a "goto label-value" statement   
   > where the label-value refers to a label in a different function. Does   
   > gcc prevent that at compile time? If not, I would expect the semantics   
   > to be Undefined Behavior, the usual cop-out when nothing useful can be   
   > said.   
   >   
   > (In an earlier discussion on this group, some years ago, I explained how   
   > labels-as-values could be added to Ada, using the type system to ensure   
   > safe and defined semantics. But I don't think such an extension would be   
   > accepted for the Ada standard.)   
   >   
      
   My guess here:   
   It is an "oh crap" situation and program either immediately or (maybe   
   not as immediately) explodes...   
      
   Otherwise, it would need to function more like a longjmp, which would   
   mean that it would likely be painfully slow.   
      
      
   So, yeah, most likely UB, of a "particularly destructive" / "unlikely to   
   be useful" kind.   
      
      
   FWIW:   
   This was not a feature that I feel inclined to support in BGBCC...   
      
      
   > Niklas   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)