prettify: print message about prettified file

This should make it much more user friendly, especially together
with the CI and pre-commit since with `--no-report-errors`
only a list of prettified files plus a summary will be reported,
instead of the list of INFO and WARNING lines for things the
user can't do anything about.

tools/prettify/prettify.py

@@ -8,7 +8,6 @@ from os import path
 import logging
 import argparse
 import errno
-import traceback
 import contextlib
 
 try:
@@ -272,7 +271,9 @@ def prettifyFile(
 
 
 def prettifyInplace(filename, backupdir=None, stdout=False, **kwargs):
-    """Same as prettify, but inplace, replaces only if needed"""
+    """Same as prettify, but inplace, replaces only if needed
+    :return: True if file was modified, False if otherwise. If stdin/stdout, always False.
+    """
 
     if filename == "stdin":
         infile = tempfile.TemporaryFile(mode="r+")
@@ -287,11 +288,11 @@ def prettifyInplace(filename, backupdir=None, stdout=False, **kwargs):
         outfile.seek(0)
         sys.stdout.write(outfile.read())
         outfile.close()
-        return
+        return False
 
     if infile == outfile:
         infile.close()
-        return
+        return False
 
     infile.seek(0)
     outfile.seek(0)
@@ -321,6 +322,8 @@ def prettifyInplace(filename, backupdir=None, stdout=False, **kwargs):
 
     outfile.close()
 
+    return changed
+
 
 def is_fypp(infile):
     FYPP_SYMBOLS = r"(#|\$|@)"
@@ -360,11 +363,6 @@ def mkdir_p(p):
             raise
 
 
-# from https://stackoverflow.com/a/14981125
-def eprint(*args, **kwargs):
-    print(*args, file=sys.stderr, **kwargs)
-
-
 def abspath(p):
     return path.abspath(path.expanduser(p))
 
@@ -422,6 +420,9 @@ def main(argv):
         False,
         "store backups of original files in backup-dir (--backup-dir option)",
     )
+    argparse_add_bool_arg(
+        parser, "quiet", False, "don't show summary or list of reformatted files"
+    )
     argparse_add_bool_arg(parser, "report-errors", True, "report warnings and errors")
     argparse_add_bool_arg(parser, "debug", False, "increase log level to debug")
 
@@ -438,7 +439,7 @@ def main(argv):
         if args.debug:
             level = logging.DEBUG
         else:
-            level = logging.INFO
+            level = logging.ERROR
 
     # the fprettify logger provides filename and line number in case of errors
     shandler = logging.StreamHandler()
@@ -461,15 +462,16 @@ def main(argv):
     prettify_logger.addHandler(shandler)
 
     failure = 0
+    total_prettified = 0
 
     for filename in args.files:
         if not path.isfile(filename) and not filename == "stdin":
-            eprint("file '{}' does not exist!".format(filename))
+            logger.error(f"file '{filename}' does not exist")
             failure += 1
             continue
 
         try:
-            prettifyInplace(
+            changed = prettifyInplace(
                 filename,
                 backupdir=args.backup_dir if args.do_backup else None,
                 stdout=args.stdout or filename == "stdin",
@@ -483,10 +485,20 @@ def main(argv):
                 upcase_omp=args.omp_upcase,
                 replace=args.replace,
             )
+
+            if changed and not args.quiet:
+                print(f"prettified {filename}")
+                total_prettified += 1
+
         except:
             logger.exception("processing file failed", extra={"ffilename": filename})
             failure += 1
 
+    if not (args.stdout or filename == "stdin" or args.quiet):
+        print(
+            f"{total_prettified} file(s) prettified, {len(args.files) - total_prettified} file(s) left unchanged."
+        )
+
     return failure > 0