[console] improve progress_message context (#12387)

This allows statements executed within a ``progress_message`` context
to emit log messages without polluting the console output.

Co-authored-by: Bénédikt Tran <[email protected]>

Author: methane

sphinx/builders/__init__.py

@@ -559,7 +559,7 @@ def write(
         with progress_message(__('preparing documents')):
             self.prepare_writing(docnames)
 
-        with progress_message(__('copying assets')):
+        with progress_message(__('copying assets'), nonl=False):
             self.copy_assets()
 
         if self.parallel_ok:

sphinx/util/display.py

@@ -62,27 +62,29 @@ class SkipProgressMessage(Exception):
 
 
 class progress_message:
-    def __init__(self, message: str) -> None:
+    def __init__(self, message: str, *, nonl: bool = True) -> None:
         self.message = message
+        self.nonl = nonl
 
     def __enter__(self) -> None:
-        logger.info(bold(self.message + '... '), nonl=True)
+        logger.info(bold(self.message + '... '), nonl=self.nonl)
 
     def __exit__(
         self,
         typ: type[BaseException] | None,
         val: BaseException | None,
         tb: TracebackType | None,
     ) -> bool:
+        prefix = "" if self.nonl else bold(self.message + ': ')
         if isinstance(val, SkipProgressMessage):
-            logger.info(__('skipped'))
+            logger.info(prefix + __('skipped'))
             if val.args:
                 logger.info(*val.args)
             return True
         elif val:
-            logger.info(__('failed'))
+            logger.info(prefix + __('failed'))
         else:
-            logger.info(__('done'))
+            logger.info(prefix + __('done'))
 
         return False