depends: Avoid using helper variables in toolchain file #31360

1. 
   hebasto commented at 1:49 pm on November 24, 2024: member

   Using helper variables has two issues:

   1. They contaminate the global namespace of the main build script.
   2. They can be used as set(var), effectively exposing a cache variable var, which makes the toolchain file susceptible to the build environment.

   The depends/Makefile can generate values with “not-set” semantics as empty strings or strings containing only spaces. For example:https://github.com/bitcoin/bitcoin/blob/2638fdb4f934be96b7c798dbac38ea5ab8a6374a/depends/Makefile#L157 Therefore, MATCHES must be used rather than STREQUAL.

2. depends: Avoid using helper variables in toolchain file

   Using helper variables has two issues:
   1. They contaminate the global namespace of the main build script.
   2. They can be used as `set(var)`, effectively exposing a cache variable
   `var`, which makes the toolchain file susceptible to the build
   environment.

   1e7cdb04fd
3. 
   DrahtBot commented at 1:50 pm on November 24, 2024: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31360.

   Reviews

   See the guideline for information on the review process. A summary of reviews will appear here.

   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #28710 (Remove the legacy wallet and BDB dependency by achow101)

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

4. DrahtBot added the label Build system on Nov 24, 2024

Contributors
hebasto DrahtBot

Labels
Build system