Merge commit d8a09b3a0 from openzfs git (by Ryan Libby):

  lua: avoid gcc -Wreturn-local-addr bug

  Avoid a bug with gcc's -Wreturn-local-addr warning with some
  obfuscation.  In buggy versions of gcc, if a return value is an
  expression that involves the address of a local variable, and even if
  that address is legally converted to a non-pointer type, a warning may
  be emitted and the value of the address may be replaced with zero.
  Howerver, buggy versions don't emit the warning or replace the value
  when simply returning a local variable of non-pointer type.

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90737

  Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
  Signed-off-by: Ryan Libby <rlibby@FreeBSD.org>
  Closes #11337

1 files changed, 6 insertions, 4 deletions

diff --git a/sys/contrib/openzfs/module/lua/ldo.c b/sys/contrib/openzfs/module/lua/ldo.c
index 0344a29fd8e8..474fe659bcef 100644
--- a/sys/contrib/openzfs/module/lua/ldo.c
+++ b/sys/contrib/openzfs/module/lua/ldo.c
@@ -33,14 +33,16 @@
 #if defined (_KERNEL) && defined(__linux__)
 #include <asm/current.h>
 static intptr_t stack_remaining(void) {
-  char local;
-  return (intptr_t)(&local - (char *)current->stack);
+  intptr_t local;
+  local = (intptr_t)&local - (intptr_t)current->stack;
+  return local;
 }
 #elif defined (_KERNEL) && defined(__FreeBSD__)
 #include <sys/pcpu.h>
 static intptr_t stack_remaining(void) {
-  char local;
-  return (intptr_t)(&local - (char *)curthread->td_kstack);
+  intptr_t local;
+  local = (intptr_t)&local - (intptr_t)curthread->td_kstack;
+  return local;
 }
 #else
 static intptr_t stack_remaining(void) {