Use pure rust secp256k1 under WASM.

[artemii235]

We have some problems compiling for WASM on MacOS.

[sergeyboyko0791]

I just found a solution 🥳

The summary:
To build mm2 in WASM on MacOS do the following:

brew install llvm
# M1
CC=/opt/homebrew/opt/llvm/bin/clang AR=/opt/homebrew/opt/llvm/bin/llvm-ar wasm-pack build --target web --out-dir wasm_build/deps/pkg/
# Intel
CC=/usr/local/opt/llvm/bin/clang AR=/usr/local/opt/llvm/bin/llvm-ar wasm-pack build --target web --out-dir wasm_build/deps/pkg/

The source: sapio-lang/sapio#146 (comment)

I'll add these steps to README.md

--------------

First of all, I faced a problem creating wasm32-unknown-unknown target when compile secp256k1-sys:

Command: wasm-pack build --target web --out-dir wasm_build/deps/pkg/
Error log:

   Compiling secp256k1-sys v0.4.0 (https://github.com/rust-bitcoin/rust-secp256k1#4ae0e7eb)
The following warnings were emitted during compilation:

warning: error: unable to create target: 'No available targets are compatible with triple "wasm32-unknown-unknown"'
warning: 1 error generated.

error: failed to run custom build command for `secp256k1-sys v0.4.0 (https://github.com/rust-bitcoin/rust-secp256k1#4ae0e7eb)`

Caused by:
  process didn't exit successfully: `/Users/bso/scm/tmp/rust-secp256k1/target/release/build/secp256k1-sys-c2a04f25427479bf/build-script-build` (exit status: 1)
  --- stdout
  TARGET = Some("wasm32-unknown-unknown")
  OPT_LEVEL = Some("3")
  HOST = Some("aarch64-apple-darwin")
  CC_wasm32-unknown-unknown = None
  CC_wasm32_unknown_unknown = None
  TARGET_CC = None
  CC = None
  CFLAGS_wasm32-unknown-unknown = None
  CFLAGS_wasm32_unknown_unknown = None
  TARGET_CFLAGS = None
  CFLAGS = None
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("false")
  CC_wasm32-unknown-unknown = None
  CC_wasm32_unknown_unknown = None
  TARGET_CC = None
  CC = None
  CFLAGS_wasm32-unknown-unknown = None
  CFLAGS_wasm32_unknown_unknown = None
  TARGET_CFLAGS = None
  CFLAGS = None
  CRATE_CC_NO_DEFAULTS = None
  running: "clang" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=wasm32-unknown-unknown" "-I" "depend/secp256k1/" "-I" "depend/secp256k1/include" "-I" "depend/secp256k1/src" "-I" "wasm-sysroot" "-Wall" "-Wextra" "-DSECP256K1_BUILD=1" "-DENABLE_MODULE_ECDH=1" "-DENABLE_MODULE_SCHNORRSIG=1" "-DENABLE_MODULE_EXTRAKEYS=1" "-DECMULT_GEN_PREC_BITS=4" "-DUSE_NUM_NONE=1" "-DUSE_FIELD_INV_BUILTIN=1" "-DUSE_SCALAR_INV_BUILTIN=1" "-DECMULT_WINDOW_SIZE=15" "-DUSE_EXTERNAL_DEFAULT_CALLBACKS=1" "-o" "/Users/bso/scm/tmp/rust-secp256k1/target/wasm32-unknown-unknown/release/build/secp256k1-sys-05a77631852afcad/out/depend/secp256k1/contrib/lax_der_parsing.o" "-c" "depend/secp256k1/contrib/lax_der_parsing.c"
  cargo:warning=error: unable to create target: 'No available targets are compatible with triple "wasm32-unknown-unknown"'
  cargo:warning=1 error generated.
  exit status: 1

  --- stderr


  error occurred: Command "clang" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=wasm32-unknown-unknown" "-I" "depend/secp256k1/" "-I" "depend/secp256k1/include" "-I" "depend/secp256k1/src" "-I" "wasm-sysroot" "-Wall" "-Wextra" "-DSECP256K1_BUILD=1" "-DENABLE_MODULE_ECDH=1" "-DENABLE_MODULE_SCHNORRSIG=1" "-DENABLE_MODULE_EXTRAKEYS=1" "-DECMULT_GEN_PREC_BITS=4" "-DUSE_NUM_NONE=1" "-DUSE_FIELD_INV_BUILTIN=1" "-DUSE_SCALAR_INV_BUILTIN=1" "-DECMULT_WINDOW_SIZE=15" "-DUSE_EXTERNAL_DEFAULT_CALLBACKS=1" "-o" "/Users/bso/scm/tmp/rust-secp256k1/target/wasm32-unknown-unknown/release/build/secp256k1-sys-05a77631852afcad/out/depend/secp256k1/contrib/lax_der_parsing.o" "-c" "depend/secp256k1/contrib/lax_der_parsing.c" with args "clang" did not execute successfully (status code exit status: 1).


Error: Compiling your crate to WebAssembly failed
Caused by: failed to execute `cargo build`: exited with exit status: 101
  full command: "cargo" "build" "--lib" "--release" "--target" "wasm32-unknown-unknown"

Related issue: rustwasm/wasm-pack#621

--------------

After installing and configuring llvm accordingly to the comment, I got the following error:

Commands:

export CC=/opt/homebrew/opt/llvm/bin/clang
export AC=/opt/homebrew/opt/llvm/bin/llvm-ac
wasm-pack build --target web --out-dir wasm_build/deps/pkg/

Error log:

Compiling secp256k1-sys v0.4.0 (https://github.com/rust-bitcoin/rust-secp256k1#4ae0e7eb)
error: failed to build archive: section too large

error: aborting due to previous error

The following warnings were emitted during compilation:

warning: In file included from depend/secp256k1/src/secp256k1.c:10:
warning: In file included from depend/secp256k1/src/assumptions.h:12:
warning: In file included from depend/secp256k1/src/util.h:16:
warning: wasm-sysroot/stdio.h:4:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_INT_SIZE = sizeof(int);
warning:                            ^
warning: wasm-sysroot/stdio.h:5:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_INT_ALIGN = alignof(int);
warning:                            ^
warning: wasm-sysroot/stdio.h:7:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_UNSIGNED_INT_SIZE = sizeof(unsigned int);
warning:                            ^
warning: wasm-sysroot/stdio.h:8:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_UNSIGNED_INT_ALIGN = alignof(unsigned int);
warning:                            ^
warning: wasm-sysroot/stdio.h:10:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_SIZE_T_SIZE = sizeof(size_t);
warning:                            ^
warning: wasm-sysroot/stdio.h:11:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_SIZE_T_ALIGN = alignof(size_t);
warning:                            ^
warning: wasm-sysroot/stdio.h:13:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_UNSIGNED_CHAR_SIZE = sizeof(unsigned char);
warning:                            ^
warning: wasm-sysroot/stdio.h:14:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_UNSIGNED_CHAR_ALIGN = alignof(unsigned char);
warning:                            ^
warning: wasm-sysroot/stdio.h:16:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_PTR_SIZE = sizeof(void*);
warning:                            ^
warning: wasm-sysroot/stdio.h:17:28: warning: 'extern' variable has an initializer [-Wextern-initializer]
warning: extern const unsigned char WASM32_PTR_ALIGN = alignof(void*);
warning:                            ^
warning: In file included from depend/secp256k1/src/secp256k1.c:13:
warning: depend/secp256k1/src/field_impl.h:266:13: warning: unused function 'rustsecp256k1_v0_4_0_fe_inv_all_var' [-Wunused-function]
warning: static void rustsecp256k1_v0_4_0_fe_inv_all_var(rustsecp256k1_v0_4_0_fe *r, const rustsecp256k1_v0_4_0_fe *a, size_t len) {
warning:             ^
warning: In file included from depend/secp256k1/src/secp256k1.c:15:
warning: depend/secp256k1/src/group_impl.h:191:13: warning: unused function 'rustsecp256k1_v0_4_0_ge_set_infinity' [-Wunused-function]
warning: static void rustsecp256k1_v0_4_0_ge_set_infinity(rustsecp256k1_v0_4_0_ge *r) {
warning:             ^
warning: depend/secp256k1/src/group_impl.h:658:12: warning: unused function 'rustsecp256k1_v0_4_0_gej_has_quad_y_var' [-Wunused-function]
warning: static int rustsecp256k1_v0_4_0_gej_has_quad_y_var(const rustsecp256k1_v0_4_0_gej *a) {
warning:            ^
warning: In file included from depend/secp256k1/src/secp256k1.c:16:
warning: In file included from depend/secp256k1/src/ecmult_impl.h:16:
warning: In file included from depend/secp256k1/src/ecmult.h:13:
warning: depend/secp256k1/src/scratch.h:24:38: warning: unused function 'rustsecp256k1_v0_4_0_scratch_create' [-Wunused-function]
warning: static rustsecp256k1_v0_4_0_scratch* rustsecp256k1_v0_4_0_scratch_create(const rustsecp256k1_v0_4_0_callback* error_callback, size_t max_size);
warning:                                      ^
warning: depend/secp256k1/src/scratch.h:26:13: warning: unused function 'rustsecp256k1_v0_4_0_scratch_destroy' [-Wunused-function]
warning: static void rustsecp256k1_v0_4_0_scratch_destroy(const rustsecp256k1_v0_4_0_callback* error_callback, rustsecp256k1_v0_4_0_scratch* scratch);
warning:             ^
warning: In file included from depend/secp256k1/src/secp256k1.c:16:
warning: depend/secp256k1/src/ecmult_impl.h:1035:12: warning: unused function 'rustsecp256k1_v0_4_0_ecmult_multi_var' [-Wunused-function]
warning: static int rustsecp256k1_v0_4_0_ecmult_multi_var(const rustsecp256k1_v0_4_0_callback* error_callback, const rustsecp256k1_v0_4_0_ecmult_context *ctx, rustsecp256k1_v0_4_0_scratch *scratch, rustsecp256k1_v0_4_0_gej *r, const rustsecp256k1_v0_4_0_scalar *inp_g_sc, rustsecp256k1_v0_4_0_ecmult_multi_callback cb, void *cbdata, size_t n) {
warning:            ^
warning: depend/secp256k1/src/ecmult_impl.h:621:12: warning: unused function 'rustsecp256k1_v0_4_0_ecmult_strauss_batch_single' [-Wunused-function]
warning: static int rustsecp256k1_v0_4_0_ecmult_strauss_batch_single(const rustsecp256k1_v0_4_0_callback* error_callback, const rustsecp256k1_v0_4_0_ecmult_context *actx, rustsecp256k1_v0_4_0_scratch *scratch, rustsecp256k1_v0_4_0_gej *r, const rustsecp256k1_v0_4_0_scalar *inp_g_sc, rustsecp256k1_v0_4_0_ecmult_multi_callback cb, void *cbdata, size_t n) {
warning:            ^
warning: depend/secp256k1/src/ecmult_impl.h:863:15: warning: unused function 'rustsecp256k1_v0_4_0_pippenger_scratch_size' [-Wunused-function]
warning: static size_t rustsecp256k1_v0_4_0_pippenger_scratch_size(size_t n_points, int bucket_window) {
warning:               ^
warning: depend/secp256k1/src/ecmult_impl.h:944:12: warning: unused function 'rustsecp256k1_v0_4_0_ecmult_pippenger_batch_single' [-Wunused-function]
warning: static int rustsecp256k1_v0_4_0_ecmult_pippenger_batch_single(const rustsecp256k1_v0_4_0_callback* error_callback, const rustsecp256k1_v0_4_0_ecmult_context *actx, rustsecp256k1_v0_4_0_scratch *scratch, rustsecp256k1_v0_4_0_gej *r, const rustsecp256k1_v0_4_0_scalar *inp_g_sc, rustsecp256k1_v0_4_0_ecmult_multi_callback cb, void *cbdata, size_t n) {
warning:            ^
warning: 19 warnings generated.
warning: warning: /Library/Developer/CommandLineTools/usr/bin/ranlib: archive library: /Users/bso/scm/tmp/rust-secp256k1/target/wasm32-unknown-unknown/release/build/secp256k1-sys-05a77631852afcad/out/libsecp256k1.a the table of contents is empty (no object file members in the library define global symbols)

error: could not compile `secp256k1-sys`

To learn more, run the command again with --verbose.
Error: Compiling your crate to WebAssembly failed
Caused by: failed to execute `cargo build`: exited with exit status: 101
  full command: "cargo" "build" "--lib" "--release" "--target" "wasm32-unknown-unknown"

--------------

But... Unexpectedly for me, the following command works 🧐

Command: CC=/opt/homebrew/opt/llvm/bin/clang AR=/opt/homebrew/opt/llvm/bin/llvm-ar wasm-pack build --target web --out-dir wasm_build/deps/pkg/

[artemii235]

@sergeyboyko0791 Could you please update the docs and add an instruction on how the WASM should be built on M1?

[artemii235]

Instruction is merged to dev.