From 8e579083b1142dab26f268d77650e680cad6b4b5 Mon Sep 17 00:00:00 2001
From: Cody Tapscott <84105208+topolarity@users.noreply.github.com>
Date: Thu, 4 Apr 2024 16:58:47 -0400
Subject: [PATCH] Make implicit function definition (in `julia_init.c`) an
 error (#936)

This is an easy thing to get wrong. Someone more familiar with Julia than
with C is not likely to recognize the significance of this error.

I've also almost never seen this intentionally ignored in the wild, so I
don't expect many false positives.
---
 src/juliaconfig.jl | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/juliaconfig.jl b/src/juliaconfig.jl
index 4424596e..ab237872 100644
--- a/src/juliaconfig.jl
+++ b/src/juliaconfig.jl
@@ -54,7 +54,8 @@ end
 
 function cflags()
     flags = IOBuffer()
-    print(flags, "-O2 -std=gnu99")
+    print(flags, " -Werror-implicit-function-declaration")
+    print(flags, " -O2 -std=gnu99")
     include = shell_escape(julia_includedir())
     print(flags, " -I", include)
     if Sys.isunix()