From 83221ecb009dab11d9967abb9aa4aa8d27fdf477 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 26 Nov 2015 00:06:41 +0100
Subject: [PATCH] Add experimental features to configure

---
 .travis.yml  | 12 ++++++------
 configure.ac | 30 ++++++++++++++++++++++++------
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 4e1e73c39f57b..3540d17d06305 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,20 +8,20 @@ compiler:
   - gcc
 env:
   global:
-    - FIELD=auto  BIGNUM=auto  SCALAR=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  schnorr=no  RECOVERY=no
+    - FIELD=auto  BIGNUM=auto  SCALAR=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  schnorr=no  RECOVERY=no  EXPERIMENTAL=no
   matrix:
     - SCALAR=32bit    RECOVERY=yes
-    - SCALAR=32bit    FIELD=32bit       ECDH=yes
+    - SCALAR=32bit    FIELD=32bit       ECDH=yes  EXPERIMENTAL=yes
     - SCALAR=64bit
     - FIELD=64bit     RECOVERY=yes
     - FIELD=64bit     ENDOMORPHISM=yes
-    - FIELD=64bit     ENDOMORPHISM=yes  ECDH=yes
+    - FIELD=64bit     ENDOMORPHISM=yes  ECDH=yes EXPERIMENTAL=yes
     - FIELD=64bit                       ASM=x86_64
     - FIELD=64bit     ENDOMORPHISM=yes  ASM=x86_64
-    - FIELD=32bit     SCHNORR=yes
+    - FIELD=32bit     SCHNORR=yes EXPERIMENTAL=yes
     - FIELD=32bit     ENDOMORPHISM=yes
     - BIGNUM=no
-    - BIGNUM=no       ENDOMORPHISM=yes SCHNORR=yes  RECOVERY=yes
+    - BIGNUM=no       ENDOMORPHISM=yes SCHNORR=yes  RECOVERY=yes EXPERIMENTAL=yes
     - BIGNUM=no       STATICPRECOMPUTATION=no
     - BUILD=distcheck
     - EXTRAFLAGS=CPPFLAGS=-DDETERMINISTIC
@@ -59,5 +59,5 @@ before_script: ./autogen.sh
 script:
  - if [ -n "$HOST" ]; then export USE_HOST="--host=$HOST"; fi
  - if [ "x$HOST" = "xi686-linux-gnu" ]; then export CC="$CC -m32"; fi
- - ./configure --enable-endomorphism=$ENDOMORPHISM --with-field=$FIELD --with-bignum=$BIGNUM --with-scalar=$SCALAR --enable-ecmult-static-precomputation=$STATICPRECOMPUTATION --enable-module-ecdh=$ECDH --enable-module-schnorr=$SCHNORR --enable-module-recovery=$RECOVERY $EXTRAFLAGS $USE_HOST && make -j2 $BUILD
+ - ./configure --enable-experimental=$EXPERIMENTAL --enable-endomorphism=$ENDOMORPHISM --with-field=$FIELD --with-bignum=$BIGNUM --with-scalar=$SCALAR --enable-ecmult-static-precomputation=$STATICPRECOMPUTATION --enable-module-ecdh=$ECDH --enable-module-schnorr=$SCHNORR --enable-module-recovery=$RECOVERY $EXTRAFLAGS $USE_HOST && make -j2 $BUILD
 os: linux
diff --git a/configure.ac b/configure.ac
index 786d8dcfb99ec..e4218669f0a5b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -93,23 +93,28 @@ AC_ARG_ENABLE(tests,
     [use_tests=$enableval],
     [use_tests=yes])
 
+AC_ARG_ENABLE(experimental,
+    AS_HELP_STRING([--enable-experimental],[allow experimental configure options (default is no)]),
+    [use_experimental=$enableval],
+    [use_experimental=no])
+
 AC_ARG_ENABLE(endomorphism,
     AS_HELP_STRING([--enable-endomorphism],[enable endomorphism (default is no)]),
     [use_endomorphism=$enableval],
     [use_endomorphism=no])
-    
+
 AC_ARG_ENABLE(ecmult_static_precomputation,
     AS_HELP_STRING([--enable-ecmult-static-precomputation],[enable precomputed ecmult table for signing (default is yes)]),
     [use_ecmult_static_precomputation=$enableval],
     [use_ecmult_static_precomputation=yes])
 
 AC_ARG_ENABLE(module_ecdh,
-    AS_HELP_STRING([--enable-module-ecdh],[enable ECDH shared secret computation (default is no)]),
+    AS_HELP_STRING([--enable-module-ecdh],[enable ECDH shared secret computation (experimental)]),
     [enable_module_ecdh=$enableval],
     [enable_module_ecdh=no])
 
 AC_ARG_ENABLE(module_schnorr,
-    AS_HELP_STRING([--enable-module-schnorr],[enable Schnorr signature module (default is no)]),
+    AS_HELP_STRING([--enable-module-schnorr],[enable Schnorr signature module (experimental)]),
     [enable_module_schnorr=$enableval],
     [enable_module_schnorr=no])
 
@@ -350,11 +355,24 @@ AC_MSG_NOTICE([Using field implementation: $set_field])
 AC_MSG_NOTICE([Using bignum implementation: $set_bignum])
 AC_MSG_NOTICE([Using scalar implementation: $set_scalar])
 AC_MSG_NOTICE([Using endomorphism optimizations: $use_endomorphism])
-AC_MSG_NOTICE([Building ECDH module: $enable_module_ecdh])
-
-AC_MSG_NOTICE([Building Schnorr signatures module: $enable_module_schnorr])
 AC_MSG_NOTICE([Building ECDSA pubkey recovery module: $enable_module_recovery])
 
+if test x"$enable_experimental" = x"yes"; then
+  AC_MSG_NOTICE([******])
+  AC_MSG_NOTICE([WARNING: experimental build])
+  AC_MSG_NOTICE([Experimental features do not have stable APIs or properties, and may not be safe for production use.])
+  AC_MSG_NOTICE([Building ECDH module: $enable_module_ecdh])
+  AC_MSG_NOTICE([Building Schnorr signatures module: $enable_module_schnorr])
+  AC_MSG_NOTICE([******])
+else
+  if test x"$enable_module_schnorr" = x"yes"; then
+    AC_MSG_ERROR([Schnorr signature module is experimental. Use --enable-experimental to allow.])
+  fi
+  if test x"$enable_module_ecdh" = x"yes"; then
+    AC_MSG_ERROR([ECDH module is experimental. Use --enable-experimental to allow.])
+  fi
+fi
+
 AC_CONFIG_HEADERS([src/libsecp256k1-config.h])
 AC_CONFIG_FILES([Makefile libsecp256k1.pc])
 AC_SUBST(SECP_INCLUDES)