How to solve "#error Unsupported architecture" when building Rust code with wasm-pack? - rust

Question

I'm trying to learn Rust and WebAssembly by building a demo app to manipulate some archive files.
After I added the "zip" crate, I was able to run cargo build successfully but not wasm-pack build (nor cargo build --target wasm32-unknown-unknown).
I am getting cargo:warning=#error Unsupported architecture when trying to build my file and clang seems somehow not happy with it.
At first I was getting some stdio.h not found, so I ran
open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg
to install them.
I am now having the following error:
Compiling bzip2-sys v0.1.7
error: failed to run custom build command for `bzip2-sys v0.1.7`
process didn't exit successfully: `/Users/projects/rust/hello-wasm/target/release/build/bzip2-sys-b7b1e1aeb1e6f42f/build-script-build` (exit code: 101)
--- stdout
TARGET = Some("wasm32-unknown-unknown")
OPT_LEVEL = Some("s")
HOST = Some("x86_64-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")
running: "clang" "-Os" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=wasm32-unknown-unknown" "-I" "bzip2-1.0.6" "-D_FILE_OFFSET_BITS=64" "-DBZ_NO_STDIO" "-o" "/Users/projects/rust/hello-wasm/target/wasm32-unknown-unknown/release/build/bzip2-sys-3be942e6fa7d3879/out/lib/bzip2-1.0.6/blocksort.o" "-c" "bzip2-1.0.6/blocksort.c"
cargo:warning=In file included from bzip2-1.0.6/blocksort.c:22:
cargo:warning=In file included from bzip2-1.0.6/bzlib_private.h:25:
cargo:warning=In file included from /usr/include/stdlib.h:62:
cargo:warning=/usr/include/sys/cdefs.h:784:2: error: Unsupported architecture
cargo:warning=#error Unsupported architecture
cargo:warning= ^
cargo:warning=In file included from bzip2-1.0.6/blocksort.c:22:
cargo:warning=In file included from bzip2-1.0.6/bzlib_private.h:25:
cargo:warning=In file included from /usr/include/stdlib.h:64:
cargo:warning=In file included from /usr/include/_types.h:27:
cargo:warning=In file included from /usr/include/sys/_types.h:33:
cargo:warning=/usr/include/machine/_types.h:34:2: error: architecture not supported
cargo:warning=#error architecture not supported
cargo:warning= ^
cargo:warning=In file included from bzip2-1.0.6/blocksort.c:22:
cargo:warning=In file included from bzip2-1.0.6/bzlib_private.h:25:
cargo:warning=In file included from /usr/include/stdlib.h:64:
cargo:warning=In file included from /usr/include/_types.h:27:
cargo:warning=/usr/include/sys/_types.h:55:9: error: unknown type name '__int64_t'; did you mean '__int128_t'?
cargo:warning=typedef __int64_t __darwin_blkcnt_t; /* total blocks */
cargo:warning= ^
cargo:warning=note: '__int128_t' declared here
[...]
Internal error occurred: Command "clang" "-Os" "-ffunction-sections" "-fdata-sections" "-fPIC" "--target=wasm32-unknown-unknown" "-I" "bzip2-1.0.6" "-D_FILE_OFFSET_BITS=64" "-DBZ_NO_STDIO" "-o" "/Users/projects/rust/hello-wasm/target/wasm32-unknown-unknown/release/build/bzip2-sys-3be942e6fa7d3879/out/lib/bzip2-1.0.6/blocksort.o" "-c" "bzip2-1.0.6/blocksort.c" with args "clang" did not execute successfully (status code exit code: 1).
I then ran:
rustup target add wasm32-unknown-unknown --toolchain nightly
rustup default nightly
to install target wasm32-unknown-unknown but I am still getting the error.
What am I missing to compile the "zip" crate for wasm ?
Environment
macOS 10.14.4
gcc -v
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 10.0.1 (clang-1001.0.46.4)
Target: x86_64-apple-darwin18.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
rustc --version
rustc 1.36.0-nightly (31a75a172 2019-04-21)
rustup show
Default host: x86_64-apple-darwin
installed toolchains
--------------------
stable-x86_64-apple-darwin
nightly-2019-04-16-x86_64-apple-darwin
nightly-x86_64-apple-darwin (default)
installed targets for active toolchain
--------------------------------------
wasm32-unknown-unknown
x86_64-apple-darwin
active toolchain
----------------
nightly-x86_64-apple-darwin (default)
rustc 1.36.0-nightly (31a75a172 2019-04-21)

Answer 1

choose one of
replace wasm32-unknown-unknown with wasm32-unknown-emscripten
remove #include <stdio.h>, printf and other standard-library calls from the C sources
implement the needed functions (printf?) for wasm32-unknown-unknown, or extract-and-copy emscripten's implementation