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Comment by lerno

16 days ago

The difference here is that a preprocessor runs before parsing and semantic analysis. In C3 compile time if runs in the analysis step, so after parsing.

So the macros and compile time execution occurs after parsing in C3, but in C everything happens at lexing, before the code is parsed.

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lerno

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owlstuffing  16 days ago

That strategy will backfire when the grammar changes in a later release. A pre-parse step is necessary for code that targets different compiler releases.

  • lerno  16 days ago

    Now I'm confused, what do you mean? What grammar changes?

    • owlstuffing  16 days ago

      Imagine v2.0 introduces a new feature that requires a parser change—one that v1.0 wouldn't be able to parse.

        $if $defined(C3_V2_PLUS):  
      // new feature
      fn f = \ -> foo(); // this won't parse in v1.0
  $else
      Callback f = ...;
  $endif

      This is also an issue if a future version of C3 introduces language level support, allowing newer compilers to compile code as if it were written for an earlier version. While this approach works well when teams standardize on a specific version’s feature set, they may still want to take advantage of performance improvements in the latest compiler.

      That said, this is a niche case and not something I’d consider a dealbreaker.

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