[Merged by Bors] - chore(Geometry/Manifold): avoid some underscore soup

[grunweg]

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[github-actions]

PR summary ddb9a51c5e

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff (regex)

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

## summary with just the declaration names:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

Declarations diff (Lean)

✅ Lean-aware diff — post-build, computed from the Lean environment (commit ddb9a51).

• +0 new declarations
• −0 removed declarations

No declaration differences.

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No changes to strong technical debt.

No changes to weak technical debt.

Current commit ddb9a51c5e
Reference commit 0ce898f5af

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[grunweg]

The underscores/specifying the instance is no longer required (but removing the @ would break the proof).

[JovanGerb]

I thought that rw [x] and rw [@x] are equivalent if x is a theorem. Are you sure of this?

[felixpernegger]

yes i also tested this

[JovanGerb]

Aha, very interesting! It turn out that the rewrite does work successfully, but it unnecessarily logs an error message.

I wrote a little tactic combinator that erases logged messages, and using this, we see that the rewrite did work:

import Mathlib

open Topology ContDiff

variable {𝕜 : Type*} [NontriviallyNormedField 𝕜]
  {E : Type*}
  [NormedAddCommGroup E] [NormedSpace 𝕜 E] {H : Type*} [TopologicalSpace H]
  {I : ModelWithCorners 𝕜 E H} {M : Type*} [TopologicalSpace M]
  
variable {e : M → H} (h : IsOpenEmbedding e) {n : ℕ∞ω}

elab "withoutErrors" tac:tactic : tactic => do
  Lean.Elab.Tactic.evalTactic tac
  modifyThe Lean.Core.State fun s => { s with messages := {} }

lemma contMDiff_isOpenEmbedding' [Nonempty M] :
    haveI := h.singletonChartedSpace; ContMDiff I I n e := by
  have := h.isManifold_singleton (I := I) (n := ω)
  withoutErrors rw [contMDiff_iff] -- succeeds!
  sorry

[JovanGerb]

This is a bug in the elaboration part of rw. It is trying to syntesize an instance that it doesn't need to synthesize anymore.

[grunweg]

So, the current code is correct - and rw throwing an error is a bug in rw (i.e., out of scope for this PR)?

[JovanGerb]

Indeed.

Maybe calling it a bug is phrased too strongly, but I think it would be better if this worked without the @. I've tried to fix this in leanprover/lean4#14593

[grunweg]

💡 Thanks for clarifying.

[JovanGerb]

Thanks, this PR looks good to me

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by JovanGerb.

[ocfnash]

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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