feat(parser): accept CONSTANT on VAR_INPUT as a no-op - #1885
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Problem: VAR_INPUT CONSTANT was rejected with E034, so sources written for CodeSys did not compile. Solution: The parser consumes the CONSTANT keyword on VAR_INPUT blocks but drops the flag from the AST; no constant semantics (validation, constant propagation in codegen) apply to the members. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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volsa
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Aug 26, 2026
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| // XXX: Not particularly clean because the AST no longer reflects the users input, but this | ||
| // is the least invasive option making CONSTANT a no-op on VAR_INPUT without touching the | ||
| // index, const evaluator, etc.; required due to CodeSys compatibility |
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Absolutely hate this plus the fact that a CONSTANT modifier is a no-op 🙃
ghaith
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Aug 26, 2026
| let constant = try_consume_var_modifier(lexer, KeywordConstant); | ||
| // Ignore the constant flag, i.e. yield false, for VAR_INPUT blocks; no constant semantics | ||
| // (validation, codegen) apply to their members | ||
| // XXX: Not particularly clean because the AST no longer reflects the users input, but this |
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constant can have a different meaning i think. Would not block this PR but it's worth considering because it popped up before. In C++ a const pointer is expressing intent, this pointer is not going to be changed for this function. i think we can leverage this constant flag exactly like this for validation rules and send it to llvm, add it to the header generation. AFAIK this was even a requested feature for the header generator.
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Problem:
VAR_INPUT CONSTANTwas rejected with validation error E034, so sources written for CodeSys did not compile.Solution: The parser consumes the
CONSTANTkeyword onVAR_INPUTblocks but drops the flag from the AST, so no constant semantics apply to the members. This is the least invasive way to make the modifier a no-op; keeping the flag would require exemptions in the validator, the indexer, and codegen, where constant propagation would otherwise replace the passed argument with the declared default. A codegen test pins that inputs keep their runtime value.🤖 Generated with Claude Code