From e2d706cbd0be4ede7fd98c020cd773bded2b5269 Mon Sep 17 00:00:00 2001
From: tkbits <96506466+2kbits@users.noreply.github.com>
Date: Wed, 25 Feb 2026 02:01:30 -0800
Subject: [PATCH] Tell cmake to use c99 to fix build with GCC 15

GCC 15 uses c23 instead of c17 by default. Apparently c23 is not backwards compatible to older C standards... This prevented me from easily compuling simh so I added a setting to tell cmake to use c99 fixing the compiling errors.

Fixes #490
---
 CMakeLists.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 120da396..e644e3ae 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -82,6 +82,9 @@ endif()
 
 project(simh VERSION "${SIMH_VERSION}" LANGUAGES C CXX)
 
+## Tell cmake we need c99 because GCC 15 defaults to c23 which breaks things.
+set(CMAKE_C_STANDARD 99)
+
 include(vcpkg-setup)
 include(GNUInstallDirs)