a19ff61e15
This PR adds support for `structure` in `mutual` blocks, allowing inductive types defined by `inductive` and `structure` to be mutually recursive. The limitations are (1) that the parents in the `extends` clause must be defined before the `mutual` block and (2) mutually recursive classes are not allowed (a limitation shared by `class inductive`). There are also improvements to universe level inference for inductive types and structures. Breaking change: structure parents now elaborate with the structure in scope (fix: use qualified names or rename the structure to avoid shadowing), and structure parents no longer elaborate with autoimplicits enabled. Internally, this is a large refactor of both the `inductive` and `structure` commands. Common material is now in `Lean.Elab.MutualInductive`, and each command plugs into this mutual inductive elaboration framework with the logic specific to the respective command. For example, `structure` has code to add projections after the inductive types are added to the environment. Closes #4182
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187 B
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invalidMutualError.lean:8:0-17:3: error: invalid mutual block: either all elements of the block must be inductive/structure declarations, or they must all be definitions/theorems/abbrevs
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