argsman: Prevent duplicate option registration across categories #35470

1. 
   pablomartin4btc commented at 8:40 PM on June 5, 2026: member

   Follow-up to #28802

   This PR enforces the invariant that option names are unique across categories.

   -<ins>Rationale</ins>:

   • While adapting the argsman_tests.cpp cases introduced in #28802 for the GNU-style parsing changes proposed in #33540, I noticed that the same option name can currently be registered in multiple categories.

   • At present in master, this ambiguity is largely masked by the existing command-line parsing behaviour. However, it relies on assumptions about how options are interpreted based on their position. Future changes to option parsing, such as the GNU-style parsing proposed in #33540, may expose this ambiguity and lead to unexpected option resolution.

   • To avoid ambiguous option resolution and make the distinction between global and command-specific options explicit, this PR adds validation in AddArg() preventing the same option name from being registered across different categories.

2. argsman: Prevent duplicate option registration across categories

   Added a validation in AddArg() preventing the same option name from
   being registered across different categories, avoiding ambiguous option
   resolution and make the distinction between global and command-specific
   options explicit.

   568afb4390
3. 
   DrahtBot commented at 8:40 PM on June 5, 2026: contributor

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35470.

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4. 
   sedited commented at 7:37 AM on June 6, 2026: contributor

   Concept ACK

5. sedited requested review from ryanofsky on Jun 9, 2026

Review Requested
ryanofsky