wasm: Update EMCC_OPTIONS default behavior

- If no EMCC_OPTIONS is specified, enable all options necessary for the
  NPM WASM package build by default.

- If it is specified, use it as-is with no added defaults. This enables full
  control over the options, e.g. for esplora, which has to disable some.

This also updates the gitlab CI build to use the correct EMCC_OPTIONS
for the esplora build.

Author: shesek

.gitlab-ci.yml

@@ -139,12 +139,12 @@ build_wally_release_files:
     - mv release wallycore-android-jni
     - tar czf wally_dist/wallycore-android-jni.tar.gz --remove-files wallycore-android-jni
     - source /opt/emsdk/emsdk_env.sh
-    - EMCC_OPTIONS="-s EXPORT_ES6=1 -s MODULARIZE=1" tools/build_wasm.sh
+    - tools/build_wasm.sh
     - cp contrib/wally_js_example.html dist/wallycore.html
     - cd dist
     - tar czf ../wally_dist/wallycore-wasm.tar.gz --remove-files wallycore.html wallycore.js wallycore.wasm
     - cd ..
-    - EMCC_OPTIONS="-s MODULARIZE=1" EXPORTED_FUNCTIONS="['_malloc','_free','_wally_init','_wally_asset_value_commitment','_wally_asset_generator_from_bytes']" tools/build_wasm.sh
+    - EMCC_OPTIONS="-s MODULARIZE=1 -s EXPORT_NAME=InitWally" EXPORTED_FUNCTIONS="['_malloc','_free','_wally_init','_wally_asset_value_commitment','_wally_asset_generator_from_bytes']" tools/build_wasm.sh
     - cd dist
     - tar czf ../wally_dist/esplora-wasm.tar.gz --remove-files wallycore.js wallycore.wasm
     - cd ..

src/wasm_package/build.sh

@@ -2,7 +2,7 @@
 set -xeo pipefail
 
 # Build WASM (Note Elements is always enabled)
-(cd ../.. && EMCC_OPTIONS="-s EXPORT_ES6=1 -s MODULARIZE=1" ./tools/build_wasm.sh)
+(cd ../.. && ./tools/build_wasm.sh)
 mkdir -p libwally_wasm && cp ../../dist/wallycore.{js,wasm} libwally_wasm/
 touch libwally_wasm/index # necessary for webpack to work (fixes "Can't resolve './' in 'wasm_package/libwally_wasm'")
 

tools/build_wasm.sh

@@ -30,7 +30,7 @@ export CFLAGS="-fno-stack-protector"
 emconfigure ./configure --build=$HOST_OS ac_cv_c_bigendian=no --disable-swig-python --disable-swig-java $DISABLE_ELEMENTS --disable-tests --enable-export-all --enable-wasm-interface
 emmake make -j $num_jobs
 
-EMCC_OPTIONS="$EMCC_OPTIONS -s EXPORT_NAME=InitWally -s WASM_BIGINT"
+: ${EMCC_OPTIONS:="-s EXPORT_ES6=1 -s WASM_BIGINT"}
 : ${OPTIMIZATION_LEVEL:=3}
 : ${EXPORTED_RUNTIME_METHODS:='cwrap,ccall,getValue,UTF8ToString'}
 # Get the list of functions to export