feat: add add_decl_doc command

src/Lean/DocString.lean

@@ -11,20 +11,20 @@ namespace Lean
 private builtin_initialize builtinDocStrings : IO.Ref (NameMap String) ← IO.mkRef {}
 private builtin_initialize docStringExt : MapDeclarationExtension String ← mkMapDeclarationExtension `docstring
 
-private def findLeadingSpacesSize (s : String) : Nat :=     
+private def findLeadingSpacesSize (s : String) : Nat :=
   let it := s.iter
   let it := it.find (· == '\n') |>.next
   let (min, it) := it.foldUntil 0 fun num c => if c == ' ' || c == '\t' then some (num + 1) else none
-  findNextLine it min 
-where 
+  findNextLine it min
+where
   consumeSpaces (it : String.Iterator) (curr min : Nat) : Nat :=
     if it.atEnd then min
     else if it.curr == ' ' || it.curr == '\t' then consumeSpaces it.next (curr + 1) min
     else findNextLine it.next (Nat.min curr min)
   findNextLine (it : String.Iterator) (min : Nat) : Nat :=
     if it.atEnd then min
-    else if it.curr == '\n' then consumeSpaces it.next 0 min 
-    else findNextLine it.next min 
+    else if it.curr == '\n' then consumeSpaces it.next 0 min
+    else findNextLine it.next min
 
 private def removeNumLeadingSpaces (n : Nat) (s : String) : String :=
   consumeSpaces n s.iter ""
@@ -33,18 +33,18 @@ where
      match n with
      | 0 => saveLine it r
      | n+1 =>
-       if it.atEnd then r 
-       else if it.curr == ' ' || it.curr == '\t' then consumeSpaces n it.next r 
+       if it.atEnd then r
+       else if it.curr == ' ' || it.curr == '\t' then consumeSpaces n it.next r
        else saveLine it r
   saveLine (it : String.Iterator) (r : String) : String :=
     if it.atEnd then r
     else if it.curr == '\n' then consumeSpaces n it.next (r.push '\n')
-    else saveLine it.next (r.push it.curr)  
-termination_by 
-  consumeSpaces n it r => (it, 1) 
+    else saveLine it.next (r.push it.curr)
+termination_by
+  consumeSpaces n it r => (it, 1)
   saveLine it r => (it, 0)
 
-private def removeLeadingSpaces (s : String) : String := 
+private def removeLeadingSpaces (s : String) : String :=
   let n := findLeadingSpacesSize s
   if n == 0 then s else removeNumLeadingSpaces n s
 

src/Lean/Parser/Command.lean

@@ -137,6 +137,8 @@ def initializeKeyword := leading_parser "initialize " <|> "builtin_initialize "
 
 @[builtinCommandParser] def «in»  := trailing_parser withOpen (" in " >> commandParser)
 
+@[builtinCommandParser] def addDocString := leading_parser docComment >> "add_decl_doc" >> ident
+
 /--
   This is an auxiliary command for generation constructor injectivity theorems for inductive types defined at `Prelude.lean`.
   It is meant for bootstrapping purposes only. -/