From 1735a78561dbe139fd138caef2d44d81f5494fe7 Mon Sep 17 00:00:00 2001
From: Khem Raj <raj.khem@gmail.com>
Date: Tue, 4 Apr 2023 12:28:11 -0700
Subject: [PATCH] Make function checks more robust within shared libs

Previous attempt to error at link like was with

https://github.com/toddr/IO-Tty/commit/1747cdf9f98cfd3aada9bf6c09f9d46297e18a5e

this however causes issues with newer clang where it detects
the assignment as -Wint-conversion warning which is treated at error
and builds with clang fail. So this is an attempt to instruct
linker explicitly to error out if the symbol is not found during link
time when building a shared library, this fixes both the problems
as reported in

https://github.com/toddr/IO-Tty/issues/23

as well as

https://github.com/toddr/IO-Tty/pull/33#issuecomment-1260147256

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 Makefile.PL | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Makefile.PL b/Makefile.PL
index eaf47e0..2e8338d 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -163,7 +163,8 @@ main ()
 #if defined (__stub_$f) || defined (__stub___$f)
 choke me
 #else
-f = $f ();
+f = $f;
+f();
 #endif
 
   ;
@@ -173,7 +174,7 @@ ESQ
 
   close(TST);
   print "Looking for $f()" . "." x (13-length($f)) . " ";
-  if (system("$cfg{'cc'} $flags $funcs{$f} functest_$f.c > functest_$f.log 2>&1")) {
+  if (system("$cfg{'cc'} $flags -Wl,--no-undefined $funcs{$f} functest_$f.c > functest_$f.log 2>&1")) {
     print "not found.\n";
   } else {
     $define{"-DHAVE_\U$f"} = undef;