From fcef9a175f810e7bfccbae9bf9e79b2b95da17ab Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@well-typed.com>
Date: Fri, 1 Apr 2022 13:28:22 -0400
Subject: configure: Make environ decl check more robust

Some platforms (e.g. Windows/clang64) declare `environ` in `<stdlib.h>`,
not `<unistd.h>`
---
 m4/fp_check_environ.m4 | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

(limited to 'm4')

diff --git a/m4/fp_check_environ.m4 b/m4/fp_check_environ.m4
index 88bf0a52de..f0daedc9c0 100644
--- a/m4/fp_check_environ.m4
+++ b/m4/fp_check_environ.m4
@@ -4,11 +4,14 @@ AC_DEFUN([FP_CHECK_ENVIRON],
 [
   dnl--------------------------------------------------------------------
   dnl * Check whether the libc headers provide a declaration for the
-  dnl environ symbol. If not then we will provide one in RtsSymbols.c. 
+  dnl environ symbol. If not then we will provide one in RtsSymbols.c.
   dnl See #20512, #20577, #20861.
+  dnl
+  dnl N.B. Windows declares environ in <stdlib.h>; most others declare it
+  dnl in <unistd.h>.
   dnl--------------------------------------------------------------------
   AC_CHECK_DECLS([environ], [], [], [
+    #include <stdlib.h>
     #include <unistd.h>
   ])
 ])
-
-- 
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