From d364f1347f05c53eea5d25a15b4ad8a62ecc85b8 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Fri, 11 Apr 2025 14:15:11 +0200
Subject: [PATCH] configure: catch asking for double resolver without https-rr

It is probably an unintentionally bad setup.

Found-by: Stefan Eissing
Closes #17025
---
 configure.ac | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 1bd039055c..0f01e4a613 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4919,14 +4919,24 @@ if test "x$want_ech" != "xno"; then
   fi
 fi
 
+AC_MSG_CHECKING([whether to enable HTTPS-RR support])
 dnl *************************************************************
 dnl check whether HTTPSRR support if desired
 dnl
 if test "x$want_httpsrr" != "xno"; then
-  AC_MSG_RESULT([HTTPSRR support is enabled])
+  AC_MSG_RESULT([yes])
   AC_DEFINE(USE_HTTPSRR, 1, [enable HTTPS RR support])
   experimental="$experimental HTTPSRR"
   curl_httpsrr_msg="enabled (--disable-httpsrr)"
+else
+  AC_MSG_RESULT([no])
+  # no HTTPSRR wanted
+  if test "$want_threaded_resolver" = "yes"; then
+    # and using the threaded resolver
+    if test "x$USE_ARES" = "x1"; then
+      AC_MSG_ERROR([without HTTPS-RR support, asking for both threaded resolver and c-ares support is ambivalent. Please drop one of them.])
+    fi
+  fi
 fi
 
 
-- 
2.47.3