https://github.com/libtom/libtompoly/commit/2803e69dcc7cac9b470360c984b62198a3774882

From 2803e69dcc7cac9b470360c984b62198a3774882 Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Wed, 19 Oct 2022 02:21:00 +0100
Subject: [PATCH] Fix -Wimplicit-function-declaration

Clang 16 will make -Wimplicit-function-declaration error by default.

For more information, see LWN.net [0] or LLVM's Discourse [1], gentoo-dev@ [2],
or the (new) c-std-porting mailing list [3].

[0] https://lwn.net/Articles/913505/
[1] https://discourse.llvm.org/t/configure-script-breakage-with-the-new-werror-implicit-function-declaration/65213
[2] https://archives.gentoo.org/gentoo-dev/message/dd9f2d3082b8b6f8dfbccb0639e6e240
[3] hosted at lists.linux.dev.

Bug: https://bugs.gentoo.org/875527
Signed-off-by: Sam James <sam@gentoo.org>
--- a/pb_add.c
+++ b/pb_add.c
@@ -17,7 +17,7 @@ int pb_add(pb_poly *a, pb_poly *b, pb_poly *c)
    pb_poly *tmp;
 
    /* grow c to be the max size */
-   y = MAX(a->used, b->used);
+   y = PB_MAX(a->used, b->used);
    if (c->alloc < y) {
       if ((err = pb_grow(c, y)) != MP_OKAY) {
          return err;
@@ -28,7 +28,7 @@ int pb_add(pb_poly *a, pb_poly *b, pb_poly *c)
    characteristic = mp_iszero(&(c->characteristic));
 
    /* add the terms */
-   z = MIN(a->used, b->used);
+   z = PB_MIN(a->used, b->used);
    for (x = 0; x < z; x++) {
        if ((err = mp_add(&(a->terms[x]), &(b->terms[x]), &(c->terms[x]))) != MP_OKAY) {
           return err;
--- a/pb_clear.c
+++ b/pb_clear.c
@@ -10,6 +10,7 @@
  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  */
 #include <tompoly.h>
+#include <stdlib.h>
 
 void pb_clear(pb_poly *a)
 {
--- a/pb_grow.c
+++ b/pb_grow.c
@@ -10,6 +10,8 @@
  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  */
 #include <tompoly.h>
+#include <stdlib.h>
+#include <string.h>
 
 int pb_grow(pb_poly *a, int size)
 {
--- a/pb_init.c
+++ b/pb_init.c
@@ -10,6 +10,7 @@
  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  */
 #include <tompoly.h>
+#include <stdlib.h>
 
 /* initialize a */
 int pb_init(pb_poly *a, mp_int *characteristic)
--- a/pb_init_size.c
+++ b/pb_init_size.c
@@ -10,6 +10,7 @@
  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  */
 #include <tompoly.h>
+#include <stdlib.h>
 
 /* initialize a */
 int pb_init_size(pb_poly *a, mp_int *characteristic, int size)
--- a/pb_shrink.c
+++ b/pb_shrink.c
@@ -10,6 +10,7 @@
  * Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
  */
 #include <tompoly.h>
+#include <stdlib.h>
 
 int pb_shrink(pb_poly *a)
 {
--- a/pb_sub.c
+++ b/pb_sub.c
@@ -17,7 +17,7 @@ int pb_sub(pb_poly *a, pb_poly *b, pb_poly *c)
    pb_poly *tmp;
 
    /* grow c to be the max size */
-   y = MAX(a->used, b->used);
+   y = PB_MAX(a->used, b->used);
    if (c->alloc < y) {
       if ((err = pb_grow(c, y)) != MP_OKAY) {
          return err;
@@ -28,7 +28,7 @@ int pb_sub(pb_poly *a, pb_poly *b, pb_poly *c)
    characteristic = mp_iszero(&(c->characteristic));
 
    /* sub the terms */
-   z = MIN(a->used, b->used);
+   z = PB_MIN(a->used, b->used);
    for (x = 0; x < z; x++) {
        if ((err = mp_sub(&(a->terms[x]), &(b->terms[x]), &(c->terms[x]))) != MP_OKAY) {
           return err;
--- a/tompoly.h
+++ b/tompoly.h
@@ -112,4 +112,13 @@ int pb_rawsize(pb_poly *a);
 int pb_toraw(pb_poly *a, unsigned char *dst);
 int pb_readraw(pb_poly *a, unsigned char *buf, int len);
 
+/* What follows should be in a private header, but it's fine for now like that. */
+
+#ifndef PB_MIN
+#define PB_MIN(x, y) (((x) < (y)) ? (x) : (y))
+#endif
+#ifndef PB_MAX
+#define PB_MAX(x, y) (((x) > (y)) ? (x) : (y))
+#endif
+
 #endif