From fa847a89dff7ca5441b1ac7b0a0ca2dc3701c38e Mon Sep 17 00:00:00 2001
From: Gleb Popov <6yearold@gmail.com>
Date: Sun, 14 Sep 2025 15:20:35 +0300
Subject: [PATCH] [flang][runtime] Use dlsym to access char** environ on
 FreeBSD

---
 flang-rt/lib/runtime/environment.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/flang-rt/lib/runtime/environment.cpp b/flang-rt/lib/runtime/environment.cpp
index 97ac56236e799..2a2e19f9f17ec 100644
--- a/flang-rt/lib/runtime/environment.cpp
+++ b/flang-rt/lib/runtime/environment.cpp
@@ -17,6 +17,10 @@
 
 #ifdef _WIN32
 extern char **_environ;
+#elif defined(__FreeBSD__)
+// FreeBSD has environ in crt rather than libc. Using "extern char** environ"
+// in the code of a shared library makes it fail to link with -Wl,--no-undefined
+// See https://reviews.freebsd.org/D30842#840642
 #else
 extern char **environ;
 #endif
@@ -104,6 +108,11 @@ void ExecutionEnvironment::Configure(int ac, const char *av[],
 
 #ifdef _WIN32
   envp = _environ;
+#elif defined(__FreeBSD__)
+  auto envpp{reinterpret_cast<char ***>(dlsym(RTLD_DEFAULT, "environ"))};
+  if (envpp) {
+    envp = *envpp;
+  }
 #else
   envp = environ;
 #endif