6893913683
This PR replaces `List.lt` with `List.Lex`, from Mathlib, and adds the new `Bool` valued lexicographic comparatory function `List.lex`. This subtly changes the definition of `<` on Lists in some situations. `List.lt` was a weaker relation: in particular if `l₁ < l₂`, then `a :: l₁ < b :: l₂` may hold according to `List.lt` even if `a` and `b` are merely incomparable (either neither `a < b` nor `b < a`), whereas according to `List.Lex` this would require `a = b`. When `<` is total, in the sense that `¬ · < ·` is antisymmetric, then the two relations coincide. Mathlib was already overriding the order instances for `List α`, so this change should not be noticed by anyone already using Mathlib. We simultaneously add the boolean valued `List.lex` function, parameterised by a `BEq` typeclass and an arbitrary `lt` function. This will support the flexibility previously provided for `List.lt`, via a `==` function which is weaker than strict equality.
160 lines
4.8 KiB
Text
160 lines
4.8 KiB
Text
/-!
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Testing for linter.constructorNameAsVariable
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This linter checks warns when a bound variable's name is the name of a constructor of the variable's
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type, which probably indicates a namespace mistake, but can be otherwise hard to find.
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The linter is designed to interact well with the suggestions provided when a non-constructor is used
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where a constructor would be expected in a pattern, so that users who don't know Lean namespaces
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will be guided to the right qualified names. Thus, both are tested together here.
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-/
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set_option linter.unusedVariables false
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inductive A where
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| x | y
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-- Test that the linter works even in the presence of errors (making it useful for confused new
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-- users)
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/--
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warning: Local variable 'x' resembles constructor 'A.x' - write '.x' (with a dot) or 'A.x' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs(drop error, warning) in
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def f : A → Unit
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| x => _
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-- Show that the linter also works when there are no errors
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/--
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warning: Local variable 'x' resembles constructor 'A.x' - write '.x' (with a dot) or 'A.x' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs(warning) in
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def g : A → Unit
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| x => ()
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-- Check that turning it off works
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#guard_msgs in
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set_option linter.constructorNameAsVariable false in
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def g' : A → Unit
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| x => ()
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-- Avoid false positives
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#guard_msgs in
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def h : A → Unit
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| z => ()
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-- Check that it works for let-bindings
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/--
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warning: Local variable 'x' resembles constructor 'A.x' - write '.x' (with a dot) or 'A.x' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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---
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warning: Local variable 'y' resembles constructor 'A.y' - write '.y' (with a dot) or 'A.y' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs in
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def i (a : A × A) : Unit :=
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let (x, y) := a
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()
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/--
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warning: Local variable 'x' resembles constructor 'A.x' - write '.x' (with a dot) or 'A.x' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs in
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def i' : Unit :=
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let x : A := .x
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()
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-- Check that it works in tactic proofs
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/--
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warning: Local variable 'x' resembles constructor 'A.x' - write '.x' (with a dot) or 'A.x' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs in
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theorem j (a : A ⊕ A) : True := by
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cases a with
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| inl x => trivial
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| inr z => trivial
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-- Top-level names do not trigger the lint
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#guard_msgs in
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def x : A := A.x
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/-! Test the interaction with the invalid match pattern error messages -/
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inductive MyProd where
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| construct : Nat → Nat → MyProd
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/--
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error: invalid pattern, constructor or constant marked with '[match_pattern]' expected
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Suggestion: 'MyProd.construct' is similar
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-/
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#guard_msgs in
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def ctorSuggestion1 (pair : MyProd) : Nat :=
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match pair with
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| construct x y => y
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-- This test is a realistic situation if a user doesn't know how Lean namespaces work
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/--
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error: invalid pattern, constructor or constant marked with '[match_pattern]' expected
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Suggestions:
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'List.Lex.below.cons',
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'List.Lex.cons',
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'List.Pairwise.below.cons',
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'List.Pairwise.cons',
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'List.Perm.below.cons',
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'List.Perm.cons',
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'List.Sublist.below.cons',
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'List.Sublist.cons',
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'List.cons'
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---
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warning: Local variable 'nil' resembles constructor 'List.nil' - write '.nil' (with a dot) or 'List.nil' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs in
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def ctorSuggestion2 (list : List α) : Nat :=
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match list with
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| nil => 0
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| cons x xs => 1 + ctorSuggestion2 xs
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-- Adding another `cons` also adds a suggestion
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inductive StringList : Type where
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| nil
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| cons (s : String) (ss : StringList)
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/--
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error: invalid pattern, constructor or constant marked with '[match_pattern]' expected
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Suggestions:
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'List.Lex.below.cons',
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'List.Lex.cons',
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'List.Pairwise.below.cons',
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'List.Pairwise.cons',
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'List.Perm.below.cons',
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'List.Perm.cons',
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'List.Sublist.below.cons',
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'List.Sublist.cons',
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'List.cons',
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'StringList.cons'
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---
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warning: Local variable 'nil' resembles constructor 'List.nil' - write '.nil' (with a dot) or 'List.nil' to use the constructor.
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note: this linter can be disabled with `set_option linter.constructorNameAsVariable false`
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-/
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#guard_msgs in
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def ctorSuggestion3 (list : List α) : Nat :=
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match list with
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| nil => 0
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| cons x xs => 1 + ctorSuggestion2 xs
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-- There isn't always a suggestion to provide
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/--
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error: invalid pattern, constructor or constant marked with '[match_pattern]' expected
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-/
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#guard_msgs in
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def ctorNoSuggestion (x : α) :=
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match x with
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| notAConstructor a b c => 42
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