--synclines adds #line 4711 after #define xyz(abc) ...\

Hi,

We are using GNU m4 1.4.18:  are there any plans for extensions a'la a c-mode via
-synclines=c,'#line __line__ "__file__"'
(also defining the lead-in per file) to add line-continuation awareness and maybe even comment awareness ?
Or a function
syncline(`#line '__line__ "__file__")
to enable switching on/off/changing the syntax?
Do you accept up-streaming contributions? -> next deadline/release?


We could also need fewer #line directives (not in comments & macros that were inserted via m4), so switching -s on and off from the included m4 file would be nice.

e.g.: fileheader included via m4 include of a template file:
#line 1 ".../CanNm_Int.h.m4"
/**
#line 1
* \file
#line 1
*
#line 1
* \brief AUTOSAR CanNm
#line 1
*
#line 1
* This file contains the implementation of the AUTOSAR
#line 1
* module CanNm.
#line 1
*
#line 1
* \version 6.19.5
#line 1
*
#line 1
* \author Elektrobit Automotive GmbH, 91058 Erlangen, Germany
#line 1
*
#line 1
* Copyright 2005 - 2021 Elektrobit Automotive GmbH
#line 1
* All rights exclusively reserved for Elektrobit Automotive GmbH,
#line 1
* unless expressly agreed to otherwise.
#line 1
*/

Or later-on: who cares where the whitespace lines came from:
#line 93 "..../xyz.m4"

#line 285

#line 350

#line 30 ".../CanNm_Int.h.m4"

#line 30
/*------------------------[Defensive programming]----------------------------*/
#line 30

#line 30


And last but not last the gem that triggered this mail:

#line 30
/** \brief Report an assertion violation to Det
#line 30
**
#line 30

#line 30
** \param[in] Condition The condition which is verified
#line 30
** \param[in] ApiId The service ID of the API function */
#line 30
#define CANNM_PRECONDITION_ASSERT_NO_EVAL(Condition, ApiId) \
#line 30
  DET_PRECONDITION_ASSERT_NO_EVAL((Condition), CANNM_MODULE_ID, CANNM_INSTANCE_ID, (ApiId))
#line 30

Thank you for your time & best regards,
Albrecht Kadlec
(participated in emacs/gnus & fvwm2/FvwmAuto/FvwmEvent development a long time ago as well as a bit of llvm: ARM-BE support more recently)