From 4204cb57715b8d505403656523bbcee8af6e6162 Mon Sep 17 00:00:00 2001
From: Justin Chen <42143810+StarryReverie@users.noreply.github.com>
Date: Sat, 3 Jan 2026 00:13:32 +0800
Subject: [PATCH] gforth: fix build with GCC 15

---
 pkgs/by-name/gf/gforth/boot-forth.nix         |  5 ++++
 .../by-name/gf/gforth/function-pointers.patch | 26 +++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 pkgs/by-name/gf/gforth/function-pointers.patch

diff --git a/pkgs/by-name/gf/gforth/boot-forth.nix b/pkgs/by-name/gf/gforth/boot-forth.nix
index 13c0cd5955e2..5451e7d56382 100644
--- a/pkgs/by-name/gf/gforth/boot-forth.nix
+++ b/pkgs/by-name/gf/gforth/boot-forth.nix
@@ -16,6 +16,11 @@ stdenv.mkDerivation {
     sha256 = "1c1bahc9ypmca8rv2dijiqbangm1d9av286904yw48ph7ciz4qig";
   };
 
+  patches = [
+    # Newer GCC rejects casting between function pointers omitting parameters
+    ./function-pointers.patch
+  ];
+
   buildInputs = [ m4 ];
 
   configureFlags = lib.optionals stdenv.hostPlatform.isDarwin [ "--build=x86_64-apple-darwin" ];
diff --git a/pkgs/by-name/gf/gforth/function-pointers.patch b/pkgs/by-name/gf/gforth/function-pointers.patch
new file mode 100644
index 000000000000..77311c0514f8
--- /dev/null
+++ b/pkgs/by-name/gf/gforth/function-pointers.patch
@@ -0,0 +1,26 @@
+diff --git a/engine/signals.c b/engine/signals.c
+index b522f19..7f89bcd 100644
+--- a/engine/signals.c
++++ b/engine/signals.c
+@@ -399,7 +399,7 @@ void install_signal_handlers(void)
+ #endif
+   };
+   int i;
+-  void (*throw_handler)() = die_on_signal ? graceful_exit : signal_throw;
++  void (*throw_handler)(int) = die_on_signal ? graceful_exit : signal_throw;
+ #ifdef SIGSTKSZ 
+   stack_t sigstack;
+   int sas_retval=-1;
+diff --git a/engine/support.c b/engine/support.c
+index 021fa22..069c32f 100644
+--- a/engine/support.c
++++ b/engine/support.c
+@@ -79,7 +79,7 @@ char *tilde_cstr(Char *from, UCell size, int clear)
+ {
+   char *s1,*s2;
+   int s1_len, s2_len;
+-  struct passwd *getpwnam (), *user_entry;
++  struct passwd *getpwnam (const char *), *user_entry;
+ 
+   if (size<1 || from[0]!='~')
+     return cstr(from, size, clear);