From 6e12e3c178fe9ad16131eb3c089bd6578976f5d6 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Tue, 3 May 2022 13:48:56 -0400
Subject: configure: Check for ffi.h

As noted in #21485, we checked for ffi.h yet then failed to throw an
error if it is missing.

Fixes #21485.
---
 m4/fp_find_libffi.m4 | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/m4/fp_find_libffi.m4 b/m4/fp_find_libffi.m4
index ddc511553c..bf52afefbb 100644
--- a/m4/fp_find_libffi.m4
+++ b/m4/fp_find_libffi.m4
@@ -49,6 +49,7 @@ AC_DEFUN([FP_FIND_LIBFFI],
    CFLAGS="$LIBFFI_CFLAGS $CFLAGS"
    LDFLAGS2="$LDFLAGS"
    LDFLAGS="$LIBFFI_LDFLAGS $LDFLAGS"
+
    if test "$HostOS" = "openbsd";
    then
      # OpenBSD's libffi is not directly linked to the libpthread but
@@ -58,10 +59,16 @@ AC_DEFUN([FP_FIND_LIBFFI],
      # symbols.
      LDFLAGS="$LDFLAGS -lpthread"
    fi
+
    AC_CHECK_LIB(ffi, ffi_call,
-    [AC_CHECK_HEADERS([ffi.h], [break], [])
-     AC_DEFINE([HAVE_SYSTEM_LIBFFI], [1], [Define to 1 if you have libffi.])],
-    [AC_MSG_ERROR([Cannot find system libffi])])
+    [AC_CHECK_HEADERS(
+      [ffi.h],
+      [AC_DEFINE([HAVE_SYSTEM_LIBFFI], [1], [Define to 1 if you have libffi.])],
+      [AC_MSG_ERROR([Cannot find ffi.h for system libffi])]
+     )],
+    [AC_MSG_ERROR([Cannot find system libffi])]
+   )
+
    CFLAGS="$CFLAGS2"
    LDFLAGS="$LDFLAGS2"
   ])
-- 
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