Module build

Building proof trees incrementally during trait solving.

This code is a bit of a mess and can hopefully be mostly ignored. For a general overview of how it works, see the comment on ProofTreeBuilder.

Structs

• ProofTreeBuilder 🔒
  The core data structure when building proof trees.
• WipCanonicalGoalEvaluation 🔒
• WipCanonicalGoalEvaluationStep 🔒
  This only exists during proof tree building and does not have a corresponding struct in inspect. We need this to track a bunch of metadata about the current evaluation.
• WipGoalEvaluation 🔒
• WipProbe 🔒

Enums

• DebugSolver 🔒
  The current state of the proof tree builder, at most places in the code, only one or two variants are actually possible.
• WipProbeStep 🔒