rust-lang / rust-lang/goals

Architectural groundwork for expansion-time evaluation

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#620 4 comments 2 reactions 1 assignee View on GitHub

@oli-obk is already working on this.

Since Jun 3, 2026.

C-tracking-issue Roadmap Goal T-compiler T-types
Dominant language
Rust
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173
Forks
119
Avg merge
6h 31m
Merged PRs (30d)
20

Description

Metadata
Point of contact @oli-obk
Team(s) compiler, types
Goal document 2026/expansion-time-evaluation

Summary

Lay the architectural groundwork for functions that can be evaluated during macro expansion. This speculative work focuses on "queryifying" the resolver and implementing a restricted trait solver mode, enabling future language features like macro fn and compiler-integrated interop tools.

Tasks and status


Note: we have updated the body to match the 2026 goal. Your original text is preserved below.

Metadata
Point of contact @tmandry
Team(s) compiler, types
Goal document 2026/expansion-time-evaluation

Summary

Lay the architectural groundwork for functions that can be evaluated during macro expansion. This speculative work focuses on "queryifying" the resolver and implementing a restricted trait solver mode, enabling future language features like macro fn and compiler-integrated interop tools.

Needs funding: This goal needs funding to proceed.

Tasks and status

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