fix(create_deprecated_modules): fix the build again (leanprover-community#37391)

The code needed updating to the new String API; it failed to build before this PR.
This also removes uses of deprecated String API.

A future PR will add CI to ensure this script builds fine.
(Future future: can we test that we tested all .lean scripts? Or have a test which builds all .lean files in scripts?)

Co-authored-by: Damiano Testa <adomani@gmail.com>

Author: grunweg

scripts/create_deprecated_modules.lean

@@ -34,7 +34,7 @@ pass `"git commit -m 'message with spaces'`, the command will be split into
 `["git", "commit", "-m", "'message", "with", "spaces'"]`, which is not what you want.
 -/
 def runCmd (s : String) : IO String := do
-  let cmd::args := s.splitOn | EStateM.throw "Please provide at least one word in your command!"
+  let cmd::args := s.splitOn | throw <| IO.userError "Please provide at least one word in your command!"
   IO.Process.run {cmd := cmd, args := args.toArray}
 
 /--
@@ -123,9 +123,9 @@ formatted as a collapsible message. In practice, `msg` is either `last modified`
 it returns the pair `(<hash>, <msg> in <PRdescr> <hash> <diff of file wrt previous commit>)`,
 formatted as a collapsible message.
 -/
-def processPrettyOneLine (log msg fname : String) : IO (String × MessageData) := do
+def processPrettyOneLine (log msg fname : String.Slice) : IO (String.Slice × MessageData) := do
   let hash := log.takeWhile (!·.isWhitespace)
-  let PRdescr := (log.drop hash.length).trim
+  let PRdescr := (log.dropWhile (!·.isWhitespace)).trimAscii
   let gitDiffCLI := s!"git diff {hash}^...{hash} -- {fname}"
   let diff ← runCmd gitDiffCLI <|> pure s!"{hash}: error in computing '{gitDiffCLI}'"
   let diffCollapsed := .trace {cls := .str .anonymous s!"{hash}"} m!"{gitDiffCLI}" #[m!"{diff}"]
@@ -146,11 +146,11 @@ If no input is provided, the default percentage is `100`.
 def mkRenamesDict (percent : Nat := 100) : IO (Std.HashMap String String) := do
   let mut dict := ∅
   let gitDiff ← runCmd s!"git diff --name-status origin/master...HEAD"
-  let lines := gitDiff.trim.splitOn "\n"
+  let lines := gitDiff.trimAscii.lines
   for git in lines do
     -- If `git` corresponds to a rename, it contains `3` segments, separated by a
     -- tab character (`\t`): `R%%`, `oldName`, `newName`.
-    let [pct, oldName, newName] := git.split (· == '\t') | continue
+    let [pct, oldName, newName] := git.split (· == '\t') |>.toList | continue
     if pct.take 1 != "R" then
       IO.println
         s!"mkRenamesDict: '{pct}' should have been of the form Rxxx, denoting a `R`ename \
@@ -160,7 +160,7 @@ def mkRenamesDict (percent : Nat := 100) : IO (Std.HashMap String String) := do
     -- This looks like a rename with a similarity index at least as big as our threshold:
     -- we add the rename to our dictionary.
     if percent ≤ pctNat then
-      dict := dict.insert oldName newName
+      dict := dict.insert oldName.toString newName.toString
     -- This looks like a rename, but the similarity index is smaller than our threshold:
     -- we report a message and do not add the rename to our dictionary.
     else
@@ -183,7 +183,8 @@ def mkModName (fname : System.FilePath) : String :=
     match cpts.getLast? with
     | none => cpts
     | some last =>
-      cpts.dropLast ++ [if last.endsWith ".lean" then last.dropRight ".lean".length else last]
+      cpts.dropLast ++
+        [if last.endsWith ".lean" then last.dropEnd ".lean".length |>.toString else last]
   ".".intercalate cpts
 
 #guard mkModName ("Mathlib" / "Data" / "Nat" / "Basic.lean") == "Mathlib.Data.Nat.Basic"
@@ -214,16 +215,16 @@ def deprecateFilePath (fname : String) (rename comment : Option String) :
   -- Retrieve the last two commits that modified `fname`:
   -- the last one is the deletion, the previous one is the last file modification.
   let log ← runCmd s!"git log --pretty=oneline -2 -- {fname}"
-  let [deleted, lastModified] := log.trim.splitOn "\n" |
-    throwError "Found {(log.trim.splitOn "\n").length} commits, but expected 2! \
+  let [deleted, lastModified] := log.lines.toList |
+    throwError "Found {log.lines.length} commits, but expected 2! \
       Please make sure the file {fname} existed at some point!"
   let (_deleteHash, deletedMsg) ← processPrettyOneLine deleted "deleted" fname
   let (modifiedHash, modifiedMsg) ← processPrettyOneLine lastModified "last modified" fname
   msgs := msgs.append #[m!"The file {fname} was\n", modifiedMsg, deletedMsg]
   -- Get the commit date, in `YYYY-MM-DD` format, of the commit deleting the file.
   let log' ← runCmd s!"git log --format=%cs -2 -- {fname}"
-  let deletionDate := (log'.trim.splitOn "\n")[0]!
-  let deprecation ← mkDeprecationWithDate deletionDate comment
+  let deletionDate := log'.lines.first?.get!
+  let deprecation ← mkDeprecationWithDate deletionDate.toString comment
   msgs := msgs.push ""
   -- Retrieve the final version of the file, before it was deleted.
   let file ← runCmd s!"git show {modifiedHash}:{fname}"
@@ -233,7 +234,7 @@ def deprecateFilePath (fname : String) (rename comment : Option String) :
       let modName := mkModName rename
       pure s!"import {modName}"
     | none => getHeader fname file false
-  let deprecatedFile := s!"{fileHeader.trimRight}\n\n{deprecation.pretty.trimRight}\n"
+  let deprecatedFile := s!"{fileHeader.trimAsciiEnd}\n\n{deprecation.pretty.trimAsciiEnd}\n"
   msgs := msgs.push <| .trace {cls := `Deprecation} m!"{fname}" #[m!"\n{deprecatedFile}"]
   return (msgs, deprecatedFile)
 
@@ -300,10 +301,10 @@ elab tk:"#find_deleted_files" nc:(ppSpace num)? pct:(ppSpace num)? bang:&"%"? :
   -- (throwing an error if that doesn't exist).
   let getHashAndMessage (n : Nat) : CommandElabM (String × MessageData) := do
     let log ← runCmd s!"git log --pretty=oneline -{n}"
-    let some last := log.trim.splitOn "\n" |>.getLast? | throwError "Found no commits!"
-    let commitHash := last.takeWhile (!·.isWhitespace)
-    let PRdescr := (last.drop commitHash.length).trim
-    return (commitHash, .trace {cls := `Commit} m!"{PRdescr}" #[m!"{commitHash}"])
+    let some last := log.lines.toList.getLast? | throwError "Found no commits!"
+    let commitHash := last.takeWhile (fun c : Char ↦ !c.isWhitespace)
+    let PRdescr := (last.dropWhile (fun c : Char ↦ !c.isWhitespace)).trimAscii
+    return (commitHash.toString, .trace {cls := `Commit} m!"{PRdescr}" #[m!"{commitHash}"])
   let getFilesAtHash (hash : String) : CommandElabM (Std.HashSet String) := do
     let files ← runCmd s!"git ls-tree -r --name-only {hash} Mathlib/"
     return .ofList <| files.splitOn "\n"
@@ -329,10 +330,10 @@ elab tk:"#find_deleted_files" nc:(ppSpace num)? pct:(ppSpace num)? bang:&"%"? :
   for fname in onlyPastFiles do
     let fnameStx := Syntax.mkStrLit fname
     let stx ← if let some newName := dict[fname]? then
-                let newNameStx := Syntax.mkStrLit newName
-                `(command|#create_deprecated_module $fnameStx rename_to $newNameStx)
-              else
-                `(command|#create_deprecated_module $fnameStx)
+      let newNameStx := Syntax.mkStrLit newName
+      `(command|#create_deprecated_module $fnameStx rename_to $newNameStx)
+    else
+      `(command|#create_deprecated_module $fnameStx)
     suggestions := suggestions.push {
       suggestion := (⟨stx.raw.updateTrailing "hello".toRawSubstring⟩ : TSyntax `command)
     }
@@ -372,6 +373,7 @@ the deprecations later on.
 -/
 
 #find_deleted_files 0
+
 /--
 info: import Mathlib.Tactic.Linter.DeprecatedModule
 import Std.Time.Zoned