[ChrisRackauckas-Claude]

Summary

init(mod) evals a @generated generated_callfunc method into the user's module whose where-parameters were named argnames, cache_tag, and id. Those bindings are in scope inside the generated body, so a user body referencing a global named id silently received the function's internal NTuple{5,UInt32} id instead of the module global (or an UndefVarError). The parameters are renamed to ˍ₋rgf₋argnames, ˍ₋rgf₋cache_tag, and ˍ₋rgf₋id, in the same hygienic style as the existing ˍ₋rgf₋args splat; init's mod.eval is the only place a generated_callfunc method is defined. A regression test checks that id/argnames/cache_tag resolve to context-module globals when defined and throw UndefVarError when not. The same collision also broke arguments with those names — on the parent, :((id,) -> id + 1) fails to compile with syntax: local variable name "id" conflicts with a static parameter — so the testset covers the argument-name cases too.

Fixes #34.

Test evidence

The new testset was run verbatim against the parent src (ddf352d) and with the fix applied:

Unfixed:

Internal binding names stay hygienic: Error During Test
  Expression: InternalNameGlobals.f_id(2) == 42
  MethodError: no method matching +(::NTuple{5, UInt32}, ::Int64)
...
Internal binding names stay hygienic: Test Failed
  Expression: InternalNameUndefGlobals.f_id(2)
    Expected: UndefVarError
  No exception thrown
Internal binding names stay hygienic: Error During Test
  Expression: @RuntimeGeneratedFunction(:((id,) -> id + 1))(2) == 3
  syntax: local variable name "id" conflicts with a static parameter
Test Summary:                        | Fail  Error  Total  Time
Internal binding names stay hygienic |    3      6      9

Fixed:

Test Summary:                        | Pass  Total  Time
Internal binding names stay hygienic |    9      9  0.4s

The original reproduction :(x -> id) now throws UndefVarError(:id, ..., Main) instead of returning (0x7596…, …).

Groups run locally (Julia 1.12.4)

• GROUP=Core julia --project -e 'using Pkg; Pkg.test()' — passed. Tail:

  Test Summary:                        | Pass  Total  Time
  Internal binding names stay hygienic |    9      9  0.2s
  PrecompileTools 1.2 workload         |    1      1  12.6s
  Embedded objects are identified by type and content |   10     10  0.3s
  Equal expressions share one compiled body           |   13     13  3.2s
       Testing RuntimeGeneratedFunctions tests passed
  

• GROUP=QA julia --project -e 'using Pkg; Pkg.test()' — passed: QA | 20 20 51.4s.
• julia --project=@runic -m Runic --inplace on both changed files; typos clean.

Not verified: julia lts (1.10) and pre, non-Linux platforms, and the 32-bit lane — CI covers those. A user argument named ˍ₋rgf₋args could in principle still collide with the splat name, but that is the pre-existing hygiene convention and not introduced here.

Reviewer pushback welcome on: whether generated_callfunc_body's own parameter names should also be hygienic for consistency (they are internal and not in scope of the generated body), and whether the testset placement next to the other globals tests in core_tests.jl is right.

Please ignore this draft until reviewed by @ChrisRackauckas.

Risk assessment

• Risk: low
• Blast radius: the static-parameter names of the @generated generated_callfunc that init(mod) evals into each user module (argnames, cache_tag and id become ˍ₋rgf₋*). The method signature type is unchanged and there is no public API change; precompile caches invalidate on a version bump as usual.
• Evidence: the new testset fails on the parent src (3 fail, 3 error) and passes on the PR (6/6). The issue's :(x -> id) now throws UndefVarError instead of returning the internal id. Symbolics 7.41.1 build_function smoke tests pass (scalar, out-of-place, in-place). The Core and QA groups pass locally.
• Independent review: Claude Code (Opus 5.5) rated it low with high confidence: a hygienic rename only, discrimination demonstrated, downstream smoke test OK. Verdict MERGE. It suggested adding a test for argument names like id (which previously failed with a syntax error) and a shorter comment; both were sent back to the author.
• Merge: auto-merge candidate once CI is green. Not verified locally: the 1.10 LTS lane and ModelingToolkit downstream.

🤖 Generated with Devin CLI 3000.11.3 (model: swe-2-high), transcript /home/crackauc/sandbox/goals/issue-backlog/jobs/fix-RuntimeGeneratedFunctions.jl-34/log.txt on amdci2.julia.csail.mit.edu

Risk assessment and review coordination by 🤖 Claude Code (model: claude-opus-5-5[1m]), https://claude.ai/code/session_01NdFVhANTF4nepTbqYxjfRP