From e6e1987584a838dba9f36f03f4f322dbaee17a3a Mon Sep 17 00:00:00 2001
From: ghpzin <ghpzin@gmail.com>
Date: Sat, 6 Dec 2025 14:21:51 +0300
Subject: [PATCH] cvs: fix build with gcc15

- add "-std=gnu17" to `env.NIX_CFLAGS_COMPILE`

Upstream had no updates since 2019

Fedora used 13k LOC patch instead and submitted it upstream:
https://src.fedoraproject.org/rpms/cvs/c/43fad212ad729bdeabfe93b1f12007a75fc2862d
https://savannah.nongnu.org/bugs/index.php?66726

Fixes build failure with gcc15:
```
sighandle.c: In function 'SIG_handle':
sighandle.c:207:18: error: too many arguments to function
'this->handler'; expected 0, have 1
  207 |                 (*this->handler)(sig);
      |                 ~^~~~~~~~~~~~~~~ ~~~
sighandle.c:59:35: note: declared here
   59 |         RETSIGTYPE              (*handler)();
      |                                   ^~~~~~~
```
---
 pkgs/by-name/cv/cvs/package.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/by-name/cv/cvs/package.nix b/pkgs/by-name/cv/cvs/package.nix
index 47c4c2f888c7..f903bc16a74c 100644
--- a/pkgs/by-name/cv/cvs/package.nix
+++ b/pkgs/by-name/cv/cvs/package.nix
@@ -46,6 +46,10 @@ stdenv.mkDerivation {
     texinfo
   ];
 
+  # Fix build with gcc15
+  # https://savannah.nongnu.org/bugs/index.php?66726
+  env.NIX_CFLAGS_COMPILE = "-std=gnu17";
+
   configureFlags = [
     "--with-editor=${nano}/bin/nano"