build: Clean up handling of module dependencies

This also makes the order in which module options are processed
consistent between CMake and autotools (the reverse order of the listing
printed to stdout).

CMakeLists.txt

@@ -51,29 +51,37 @@ endif()
 
 option(SECP256K1_INSTALL "Enable installation." ${PROJECT_IS_TOP_LEVEL})
 
-option(SECP256K1_ENABLE_MODULE_ECDH "Enable ECDH module." ON)
-if(SECP256K1_ENABLE_MODULE_ECDH)
-  add_compile_definitions(ENABLE_MODULE_ECDH=1)
-endif()
+## Modules
 
+# We declare all options before processing them, to make sure we can express
+# dependendencies while processing.
+option(SECP256K1_ENABLE_MODULE_ECDH "Enable ECDH module." ON)
 option(SECP256K1_ENABLE_MODULE_RECOVERY "Enable ECDSA pubkey recovery module." OFF)
-if(SECP256K1_ENABLE_MODULE_RECOVERY)
-  add_compile_definitions(ENABLE_MODULE_RECOVERY=1)
-endif()
-
 option(SECP256K1_ENABLE_MODULE_EXTRAKEYS "Enable extrakeys module." ON)
 option(SECP256K1_ENABLE_MODULE_SCHNORRSIG "Enable schnorrsig module." ON)
+option(SECP256K1_ENABLE_MODULE_ELLSWIFT "Enable ElligatorSwift module." ON)
+
+# Processing must be done in a topological sorting of the dependency graph
+# (dependent module first).
+if(SECP256K1_ENABLE_MODULE_ELLSWIFT)
+  add_compile_definitions(ENABLE_MODULE_ELLSWIFT=1)
+endif()
+
 if(SECP256K1_ENABLE_MODULE_SCHNORRSIG)
   set(SECP256K1_ENABLE_MODULE_EXTRAKEYS ON)
   add_compile_definitions(ENABLE_MODULE_SCHNORRSIG=1)
 endif()
+
 if(SECP256K1_ENABLE_MODULE_EXTRAKEYS)
   add_compile_definitions(ENABLE_MODULE_EXTRAKEYS=1)
 endif()
 
-option(SECP256K1_ENABLE_MODULE_ELLSWIFT "Enable ElligatorSwift module." ON)
-if(SECP256K1_ENABLE_MODULE_ELLSWIFT)
-  add_compile_definitions(ENABLE_MODULE_ELLSWIFT=1)
+if(SECP256K1_ENABLE_MODULE_RECOVERY)
+  add_compile_definitions(ENABLE_MODULE_RECOVERY=1)
+endif()
+
+if(SECP256K1_ENABLE_MODULE_ECDH)
+  add_compile_definitions(ENABLE_MODULE_ECDH=1)
 endif()
 
 option(SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS "Enable external default callback functions." OFF)

configure.ac

@@ -387,29 +387,29 @@ SECP_CFLAGS="$SECP_CFLAGS $WERROR_CFLAGS"
 ### Handle module options
 ###
 
-if test x"$enable_module_ecdh" = x"yes"; then
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDH=1"
-fi
-
-if test x"$enable_module_recovery" = x"yes"; then
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_RECOVERY=1"
+# Processing must be done in a reverse topological sorting of the dependency graph
+# (dependent module first).
+if test x"$enable_module_ellswift" = x"yes"; then
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ELLSWIFT=1"
 fi
 
 if test x"$enable_module_schnorrsig" = x"yes"; then
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_SCHNORRSIG=1"
   enable_module_extrakeys=yes
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_SCHNORRSIG=1"
 fi
 
-if test x"$enable_module_ellswift" = x"yes"; then
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ELLSWIFT=1"
-fi
-
-# Test if extrakeys is set after the schnorrsig module to allow the schnorrsig
-# module to set enable_module_extrakeys=yes
 if test x"$enable_module_extrakeys" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_EXTRAKEYS=1"
 fi
 
+if test x"$enable_module_recovery" = x"yes"; then
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_RECOVERY=1"
+fi
+
+if test x"$enable_module_ecdh" = x"yes"; then
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDH=1"
+fi
+
 if test x"$enable_external_default_callbacks" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1"
 fi