chore: upstream Std.Lean.LocalContext (#3275)

src/Lean/LocalContext.lean

@@ -141,6 +141,15 @@ def hasExprMVar : LocalDecl → Bool
   | cdecl (type := t) ..              => t.hasExprMVar
   | ldecl (type := t) (value := v) .. => t.hasExprMVar || v.hasExprMVar
 
+/--
+Set the kind of a `LocalDecl`.
+-/
+def setKind : LocalDecl → LocalDeclKind → LocalDecl
+  | cdecl index fvarId userName type bi _, kind =>
+      cdecl index fvarId userName type bi kind
+  | ldecl index fvarId userName type value nonDep _, kind =>
+      ldecl index fvarId userName type value nonDep kind
+
 end LocalDecl
 
 /-- A LocalContext is an ordered set of local variable declarations.
@@ -311,6 +320,13 @@ def renameUserName (lctx : LocalContext) (fromName : Name) (toName : Name) : Loc
       { fvarIdToDecl := map.insert decl.fvarId decl
         decls        := decls.set decl.index decl }
 
+/--
+Set the kind of the given fvar.
+-/
+def setKind (lctx : LocalContext) (fvarId : FVarId)
+    (kind : LocalDeclKind) : LocalContext :=
+  lctx.modifyLocalDecl fvarId (·.setKind kind)
+
 def setBinderInfo (lctx : LocalContext) (fvarId : FVarId) (bi : BinderInfo) : LocalContext :=
   modifyLocalDecl lctx fvarId fun decl => decl.setBinderInfo bi
 
@@ -451,6 +467,27 @@ def sanitizeNames (lctx : LocalContext) : StateM NameSanitizerState LocalContext
             modify fun s => s.insert decl.userName
             pure lctx
 
+/--
+Given an `FVarId`, this function returns the corresponding user name,
+but only if the name can be used to recover the original FVarId.
+-/
+def getRoundtrippingUserName? (lctx : LocalContext) (fvarId : FVarId) : Option Name := do
+  let ldecl₁ ← lctx.find? fvarId
+  let ldecl₂ ← lctx.findFromUserName? ldecl₁.userName
+  guard <| ldecl₁.fvarId == ldecl₂.fvarId
+  some ldecl₁.userName
+
+/--
+Sort the given `FVarId`s by the order in which they appear in `lctx`. If any of
+the `FVarId`s do not appear in `lctx`, the result is unspecified.
+-/
+def sortFVarsByContextOrder (lctx : LocalContext) (hyps : Array FVarId) : Array FVarId :=
+  let hyps := hyps.map fun fvarId =>
+    match lctx.fvarIdToDecl.find? fvarId with
+    | none => (0, fvarId)
+    | some ldecl => (ldecl.index, fvarId)
+  hyps.qsort (fun h i => h.fst < i.fst) |>.map (·.snd)
+
 end LocalContext
 
 /-- Class used to denote that `m` has a local context. -/