From 35b7888c9b5f217dd2911c0ba93519df36e97922 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@lysator.liu.se>
Date: Mon, 11 Jul 2022 01:10:19 +0200
Subject: Rewrite handel-preprocessing-tokens.

---
 module/c/cpp-environment.scm | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'module/c/cpp-environment.scm')

diff --git a/module/c/cpp-environment.scm b/module/c/cpp-environment.scm
index 2ad60b56..2a943496 100644
--- a/module/c/cpp-environment.scm
+++ b/module/c/cpp-environment.scm
@@ -19,7 +19,9 @@
 
            enter-active-if
            enter-inactive-if
+           flip-flop-if
            leave-if
+           in-comment-block?
 
            enter-file
            leave-file
@@ -97,9 +99,19 @@
 (define (enter-inactive-if environment)
   (modify environment cpp-if-status xcons 'inactive-if))
 
+;; for #else
+(define (flip-flop-if environment)
+  ((if (in-comment-block? environment)
+       enter-active-if
+       enter-inactive-if)
+   (leave-if environment)))
+
 (define (leave-if environment)
   (modify environment cpp-if-status cdr))
 
+(define (in-comment-block? environment)
+  (eq? 'inactive-if (get environment cpp-if-status car*)))
+
 
 
 (define (enter-file environment filename)
-- 
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