From 085e316fd1353216815189cd45a8cc516561abe2 Mon Sep 17 00:00:00 2001
From: Matt Jolly <kangie@gentoo.org>
Date: Tue, 3 Nov 2026 13:30:58 +1000
Subject: [PATCH] auto.def: fix getloadavg() feature detection with strict
 C99/C23

Modern compilers treat implicit function declarations as errors by default
(e.g., GCC 14+, Clang 16+). The previous check failed because:

1. Generic cc-check-functions can clash with incompatible types.
2. getloadavg() requires _DEFAULT_SOURCE on glibc to be visible in
   system headers, and may reside in <stdlib.h> rather than <unistd.h>.

Without these headers and macros defined in the right order, the test
failed with -Werror=implicit-function-declaration, leading autosetup
to incorrectly define FOSSIL_OMIT_LOAD_AVERAGE.

Replace the check with a direct cctest defining _DEFAULT_SOURCE before
including <stdlib.h> and <unistd.h>.

Signed-off-by: Matt Jolly <kangie@gentoo.org>
--- a/auto.def
+++ b/auto.def
@@ -802,9 +802,14 @@ if {[cctest -link 1 -includes {unistd.h} -code "getpass(0);"]} {
   msg-result "Found getpass() with unistd.h"
 }
 
-# Check for getloadavg(), and if it doesn't exist, define FOSSIL_OMIT_LOAD_AVERAGE
-if {![cc-check-functions getloadavg] ||
-    ![cctest -link 1 -includes {unistd.h} -code "double a\[3\]; getloadavg(a,3);"]} {
+# Check for getloadavg(), ensuring feature macros and appropriate headers are present
+if {![cctest -link 1 -declare {
+  #ifndef _DEFAULT_SOURCE
+  #define _DEFAULT_SOURCE 1
+  #endif
+  #include <stdlib.h>
+  #include <unistd.h>
+} -code "double a\[3\]; return getloadavg(a, 3) < 0;"]} {
   define FOSSIL_OMIT_LOAD_AVERAGE 1
   msg-result "Load average support unavailable"
 }
-- 
2.56.0