From 3641829198ff85477deda496a51f74e0a6972d37 Mon Sep 17 00:00:00 2001
From: Patrick Pelissier <patrick.pelissier@gmail.com>
Date: Fri, 16 Sep 2022 18:46:13 +0200
Subject: [PATCH] M_INC (resp. M_DEC) of M_UNDERFLOW (resp. M_OVERFLOW) will
 keep the initial error.

---
 m-core.h           | 2 ++
 tests/test-mcore.c | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/m-core.h b/m-core.h
index fe30333f..41550516 100644
--- a/m-core.h
+++ b/m-core.h
@@ -523,6 +523,7 @@ M_BEGIN_PROTECTED_CODE
 #define M_INC_52 53
 #define M_INC_53 M_OVERFLOW
 #define M_INC_M_OVERFLOW M_OVERFLOW
+#define M_INC_M_UNDERFLOW M_UNDERFLOW
 
 
 /* Decrement the number given in argument (from [0..52[) 
@@ -531,6 +532,7 @@ M_BEGIN_PROTECTED_CODE
 */
 #define M_DEC(x)          M_C(M_DEC_, x)
 #define M_DEC_M_UNDERFLOW M_UNDERFLOW
+#define M_DEC_M_OVERFLOW M_OVERFLOW
 #define M_DEC_0 M_UNDERFLOW
 #define M_DEC_1 0
 #define M_DEC_2 1
diff --git a/tests/test-mcore.c b/tests/test-mcore.c
index cc47b542..bec5bb38 100644
--- a/tests/test-mcore.c
+++ b/tests/test-mcore.c
@@ -156,6 +156,9 @@ static void test_incdec(void)
   assert(!M_KEYWORD_P(M_OVERFLOW, M_ADD(M_MAX_NB_ARGUMENT, 1)));
   assert(M_KEYWORD_P(M_OVERFLOW, M_ADD(M_MAX_NB_ARGUMENT, 2)));
   assert(M_KEYWORD_P(M_OVERFLOW, M_ADD(M_MAX_NB_ARGUMENT, 3)));
+  // Test if the initial error is not lost in translation
+  assert(M_KEYWORD_P(M_UNDERFLOW, M_INC(M_UNDERFLOW)));
+  assert(M_KEYWORD_P(M_OVERFLOW, M_DEC(M_OVERFLOW)));
 
   assert(M_AND(0, 0) == 0);
   assert(M_AND(0, 1) == 0);