From 3e4c23188fc0c0ac9aea53daffb36c2514f1f4f0 Mon Sep 17 00:00:00 2001
From: Fuzzbawls <fuzzbawls@gmail.com>
Date: Wed, 2 Jul 2025 20:07:07 -0700
Subject: [PATCH] Build: Ubuntu Bionic gmp detection workaround

Ubuntu Bionic's libgmp-dev package doesn't include pkgconfig files, so we need to do some fallback checking during the configure process.
---
 configure.ac | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 8abbc384bf4d..4fe76b2f43cd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1169,7 +1169,14 @@ if test x$use_pkgconfig = xyes; then
           PKG_CHECK_MODULES([EVENT_PTHREADS], [libevent_pthreads], [], [AC_MSG_ERROR([libevent_pthreads not found.])])
         fi
         PKG_CHECK_MODULES([SODIUM], [libsodium], [], [AC_MSG_ERROR([libsodium not found.])])
-        PKG_CHECK_MODULES([GMP], [gmp], [], [AC_MSG_ERROR([libgmp not found.])])
+        dnl Ubuntu Bionic's libgmp-dev package doesn't include pkgconfig files,
+        dnl so we need to do some gymnastics here.
+        dnl TODO: Remove this drill down once Ubuntu Bionic is no longer supported.
+        PKG_CHECK_MODULES([GMP], [gmp], [], [
+          AC_CHECK_HEADER([gmp.h], [
+            AC_CHECK_LIB([gmp], [__gmpz_init], [LIBS="$LIBS -lgmp"], [AC_MSG_ERROR([libgmp missing])])
+          ], [AC_MSG_ERROR([libgmp headers missing])])
+        ])
       fi
 
       if test "x$use_zmq" = "xyes"; then