The 'gcd' module provides a gcd() function with 'unsigned long' parameters.
But some packages (such as GNU gettext) need it with 'size_t' parameters.
This matters, because on native Windows, 'size_t' is larger than 'unsigned
long'.
(Platforms where 'size_t' is smaller than 'unsigned long', such as Windows 3.1,
are not relevant here.)
2025-06-22 Bruno Haible <br...@clisp.org>
gcd: Allow customizing the parameter and result type.
* lib/gcd.h (GCD_WORD_T): New type.
(gcd): Use GCD_WORD_T instead of 'unsigned long'.
* lib/gcd.c (WORD_T): Likewise.
diff --git a/lib/gcd.c b/lib/gcd.c
index 8a7fb8ed10..25170abfc6 100644
--- a/lib/gcd.c
+++ b/lib/gcd.c
@@ -22,7 +22,7 @@
#ifndef WORD_T
/* Specification. */
# include "gcd.h"
-# define WORD_T unsigned long
+# define WORD_T GCD_WORD_T
# define GCD gcd
#endif
diff --git a/lib/gcd.h b/lib/gcd.h
index 02a8adccd9..24b8ad54bf 100644
--- a/lib/gcd.h
+++ b/lib/gcd.h
@@ -18,13 +18,25 @@
#ifndef _GCD_H
#define _GCD_H
+/* Before including this file, you may define:
+ GCD_WORD_T The parameter type and result type of the gcd function.
+ */
+
+#ifdef GCD_WORD_T
+/* Make sure that GCD_WORD_T is defined as a type. */
+# include <stddef.h>
+# include <stdint.h>
+#else
+# define GCD_WORD_T unsigned long
+#endif
+
#ifdef __cplusplus
extern "C" {
#endif
/* Return the greatest common divisor of a > 0 and b > 0. */
-extern unsigned long gcd (unsigned long a, unsigned long b);
+extern GCD_WORD_T gcd (GCD_WORD_T a, GCD_WORD_T b);
#ifdef __cplusplus
