Add support for building for wasm32-wasi target. (#477)

Signed-off-by: Piotr Sikora <[email protected]>

Author: PiotrSikora

docs/index.md

@@ -77,11 +77,17 @@ Currently the most common approach to managing external dependencies is using
 
 ## WebAssembly
 
-To build a `rust_binary` for wasm32-unknown-unknown add the `--platforms=@io_bazel_rules_rust//rust/platform:wasm` flag.
+To build a `rust_binary` for `wasm32-unknown-unknown` target add the `--platforms=@io_bazel_rules_rust//rust/platform:wasm` flag.
 
 ```command
 bazel build @examples//hello_world_wasm --platforms=@io_bazel_rules_rust//rust/platform:wasm
 ```
 
-`rust_wasm_bindgen` will automatically transition to the wasm platform and can be used when
-building wasm code for the host target.
+To build a `rust_binary` for `wasm32-wasi` target add the `--platforms=@io_bazel_rules_rust//rust/platform:wasi` flag.
+
+```command
+bazel build @examples//hello_world_wasm --platforms=@io_bazel_rules_rust//rust/platform:wasi
+```
+
+`rust_wasm_bindgen` will automatically transition to the `wasm` platform and can be used when
+building WebAssembly code for the host target.

rust/known_shas.bzl

@@ -115,6 +115,7 @@ FILE_KEY_TO_SHA = {
     "2020-02-16/rust-nightly-x86_64-unknown-linux-gnu": "b4f6ce68cc5fde78dc7ab06db6a6f30abde85ba6e5360ea3f75fb8c80232ad38",
     "2020-02-16/rust-std-nightly-aarch64-unknown-linux-gnu": "ef3c2edd450ef3ef214a5cc412de4527631f9324a28168997233a9ebea6f08c9",
     "2020-02-16/rust-std-nightly-wasm32-unknown-unknown": "dcc9ce64c62e2100b35194b6a9ed3d9a7572e1bbf28ca09da687af82ff1dbfc9",
+    "2020-02-16/rust-std-nightly-wasm32-wasi": "6e3c13f44ea6e997b5fb0a3818ee8cb850c9654857a438f6e8df42a6e1decf75",
     "2020-02-16/rust-std-nightly-x86_64-apple-darwin": "d391be4bdb713356fb34cdc03475a830e6bd4476639c46ef19a8a4c05513bc4a",
     "2020-02-16/rust-std-nightly-x86_64-unknown-freebsd": "6575eabdfaed4b0490cdfffcbb5860036dcc36bebdabc58d839c088ff5556a6f",
     "2020-02-16/rust-std-nightly-x86_64-unknown-linux-gnu": "28a169e9b0f0986a50254caf14be863cf6f1ed3aec8342a7fa756dc1af76f38b",
@@ -382,61 +383,73 @@ FILE_KEY_TO_SHA = {
     "rust-std-1.35.0-x86_64-unknown-linux-gnu": "5dfa92661ff1a22680785bd6999b6117ae66841e2bd9e5318eb97002956131e4",
     "rust-std-1.36.0-aarch64-unknown-linux-gnu": "22bfc32b5003c3d5259babb202f3f66be16fa6f3c75c20f429a16d7ef5eb1928",
     "rust-std-1.36.0-wasm32-unknown-unknown": "7fc1d9f19f6674f73fb89c24aeb741adc59896da6d7ce2e16317aa1fb084bea4",
+    "rust-std-1.36.0-wasm32-wasi": "382dd29fa294ef53272984b9121e07d2b50cc131c561bb7ab72bdebda3abc031",
     "rust-std-1.36.0-x86_64-apple-darwin": "7c6806809e010e5fba1780007ecff5c31f0ad2fcac1b414b98ca3baa0fb41b36",
     "rust-std-1.36.0-x86_64-unknown-freebsd": "a2a923cbfa3481af66c22673cac38e7cb70e26333318ad59c27b8b6ac16a84fe",
     "rust-std-1.36.0-x86_64-unknown-linux-gnu": "f92425592c02d4681a5c5ae43ac3ad7ddcc218da50fc651ddc5c2240843a7f31",
     "rust-std-1.37.0-aarch64-unknown-linux-gnu": "60d64dde9178fdb698b44315b182375916116e30f5fe7f0d8278dd62eb15e7b3",
     "rust-std-1.37.0-wasm32-unknown-unknown": "b55f82540aa900d2d1d1f6879c9374a8efc78d9eeb20af181ee30182b7f9688c",
+    "rust-std-1.37.0-wasm32-wasi": "551ee5f9adbf24c637e914148c0f161e9e2175aa7d39e5b486d1dd817fb47dec",
     "rust-std-1.37.0-x86_64-apple-darwin": "0b3fe2575b55a739f409a9d76d05c4bb32494691bde5043d77ba4d39ac182f20",
     "rust-std-1.37.0-x86_64-unknown-freebsd": "8783a667ea9c46f27027d494098c51563faa734c5ddb23c6b9b3eda804eb9742",
     "rust-std-1.37.0-x86_64-unknown-linux-gnu": "09a531a97a16701eb794ecbeeded5d8f8da33da7f1bd372661ad385e3f31c048",
     "rust-std-1.38.0-aarch64-unknown-linux-gnu": "0725ae9f55639c648fdaba06129de395ed839a7d1aab6aebfd21f26cbe1ce7ca",
     "rust-std-1.38.0-wasm32-unknown-unknown": "9634130c797e8c1fd1d7bbdfd48a32e85e2dd3512ffb2b51974374308cf581cf",
+    "rust-std-1.38.0-wasm32-wasi": "becb178cecc2d2137e006c24e6988d79390f96dcd65cc2e8b2f475a8fdab4bfc",
     "rust-std-1.38.0-x86_64-apple-darwin": "b1a986e8676aaed25959e9f6dd7c8c5aa67fb829d0d694edea34d8169658a125",
     "rust-std-1.38.0-x86_64-unknown-freebsd": "9f1d88449ef56c31ebc514873ba4d5889fa12697c4c2ea1071f15127f301ac4d",
     "rust-std-1.38.0-x86_64-unknown-linux-gnu": "cd50ec3384d79aae89ffdacf09715b68b1b5562657e993f26f67b9458e92dfdd",
     "rust-std-1.39.0-aarch64-unknown-linux-gnu": "adbecacf6cf0ed19df2496cc648b16192c0bd085d7e6f670edcea4dd28ab37df",
     "rust-std-1.39.0-wasm32-unknown-unknown": "654905b39eae031282a9db9bfa47504c23aa4bbc7d22b769b9bd2f6ca8b61cee",
+    "rust-std-1.39.0-wasm32-wasi": "e7f008fd1f7c902f5ba7777d8a4346783392bd40813c79381bd7497fbcf19be0",
     "rust-std-1.39.0-x86_64-apple-darwin": "ebd058b16590e2c1a73f5de59d169c8c11be6014934cb083afc84accdccd40d9",
     "rust-std-1.39.0-x86_64-unknown-freebsd": "94a71addd6983ae844be1cd403926c947766b72f032a083fd1be73f18cf329d9",
     "rust-std-1.39.0-x86_64-unknown-linux-gnu": "2ddad802f048acaa5cd48f1105c18c7f4de32dc9569ac4d64bfcbb3d8c155cb7",
     "rust-std-1.40.0-aarch64-unknown-linux-gnu": "e1a1bc577d51556c53e39d4f11fb4918f0ebf27e166ff63321b2991754706d16",
     "rust-std-1.40.0-wasm32-unknown-unknown": "e3f68aa04c97fb8f5f595d47f417221afb4b0c49d177a2cde7935e3afdd45947",
+    "rust-std-1.40.0-wasm32-wasi": "814d780d7296cc8a8969536f99e8b591fc68d9290e399f01c59cf86d32303718",
     "rust-std-1.40.0-x86_64-apple-darwin": "1eff41b353403cc284a09debb00cfd41d663447eabf5ad2d4cf736c8c8db0458",
     "rust-std-1.40.0-x86_64-unknown-freebsd": "90a41f80e2501ac2b036b7cdf269db19a5204aeec257bd585074508f1a6ba2c9",
     "rust-std-1.40.0-x86_64-unknown-linux-gnu": "735affaca1370699f9bc3fd7b1320694afd250923d283d88c842b7913a97d083",
     "rust-std-1.41.0-aarch64-unknown-linux-gnu": "59b8dab431af29dcd28c6e92e82a488ebb20dbb5dff93ca14119ba8e2fabd9c8",
     "rust-std-1.41.0-wasm32-unknown-unknown": "0974d40a9f54bd9dda88c20ffa1778fa90ee77a549a8f30ed13477b55e142a63",
+    "rust-std-1.41.0-wasm32-wasi": "e50c63deae8a8bc81d438f73bc885e5de7fa282784171b53e3eebf8f41d8f7d1",
     "rust-std-1.41.0-x86_64-apple-darwin": "c917af985d879376d8906e7c81ceacb06e65ea7b229ccf81505f8bd6cf5abf64",
     "rust-std-1.41.0-x86_64-unknown-freebsd": "4436e80598592398724daf0efc33b2a6505bebde59c021d3e894d605ae5255dd",
     "rust-std-1.41.0-x86_64-unknown-linux-gnu": "b563fc979eea8372f5b371e10f0857e79cdffc34b124c7a7b0d89014d1b351b7",
     "rust-std-1.42.0-aarch64-unknown-linux-gnu": "1343f51fc87049327233cee8941629c3d7dfdc425d359385f93665de3d46711b",
     "rust-std-1.42.0-wasm32-unknown-unknown": "695439ef4099f2a1da7c9932e556b3985f4ede5b27e6ef260d670bfe4bc3894b",
+    "rust-std-1.42.0-wasm32-wasi": "077bb250b6df47f1350ea875645fd388d3e6df69830ab49627fe6f6bea5887ad",
     "rust-std-1.42.0-x86_64-apple-darwin": "1d61e9ed5d29e1bb4c18e13d551c6d856c73fb8b410053245dc6e0d3b3a0e92c",
     "rust-std-1.42.0-x86_64-unknown-freebsd": "76e0f0f7275e114908b0ce2bf39813eaa580af92cc1fab31496ca37ba9d5703e",
     "rust-std-1.42.0-x86_64-unknown-linux-gnu": "e6bf5495a8b1cfb849fce2753404b3b7ce7fba0c5d743d940fac3ee4558fda26",
     "rust-std-1.43.0-aarch64-unknown-linux-gnu": "f4b80b12ecf14e97937cd24573e82f306f147db6266dc5a2cb27aaeaf49398a7",
     "rust-std-1.43.0-wasm32-unknown-unknown": "efe2061e7b9711f51b560c7770ebe372003beb9beddb363f27c3960ee12135cd",
+    "rust-std-1.43.0-wasm32-wasi": "6ece090d05853a54bb7f6e4985840cf01dc4857eda0f375bc8e35846d1d533e9",
     "rust-std-1.43.0-x86_64-apple-darwin": "c75d37579b9e143ebd98ae2fe42c818fd47e0a2763b2a9bdd7e6b9954509d735",
     "rust-std-1.43.0-x86_64-unknown-freebsd": "3c9b450b826874be5c3f35f7cb923f02d4769b81f763fef21c9c0d3a80532c2c",
     "rust-std-1.43.0-x86_64-unknown-linux-gnu": "84fd8ddaaa217b82c563d4a32a690da2c399388258a3d2baf180992c21938af5",
     "rust-std-1.44.0-aarch64-unknown-linux-gnu": "fafb49cc7264a8621c17e8954ec2e0a78e097395b285edb5c1639c61ffb8142c",
     "rust-std-1.44.0-wasm32-unknown-unknown": "8e12796a0c2fb083953042218f832bdeb78da1bfaf67b9dfe3d719920084d755",
+    "rust-std-1.44.0-wasm32-wasi": "ac0ffeb48bd4be6dd460c5665fc52bb4da2be15e5ecdefa4bf73c6db7392759a",
     "rust-std-1.44.0-x86_64-apple-darwin": "af58f742764949765e09bb60bd1c16025a79a1be8152996fd5b3a44e5df90311",
     "rust-std-1.44.0-x86_64-unknown-freebsd": "a0315d028e72e221291dba257e8212e564574d87362cb07e06dc15950d1e6788",
     "rust-std-1.44.0-x86_64-unknown-linux-gnu": "3b7a4eede0ca550c256ca6721877de0154c27e71196d8b9a980a480682ead0aa",
     "rust-std-1.45.0-aarch64-unknown-linux-gnu": "816f6cc132db84617bfde6ad47336bfb020552a45bd0a10250c4e420d512d5ad",
     "rust-std-1.45.0-wasm32-unknown-unknown": "1b4f40be1d0f18a5a04f9f706fef74db0e299046557a706a4dc31a2b36d8de21",
+    "rust-std-1.45.0-wasm32-wasi": "1ef0e8e09ad39275a188bc88d4969c4d1e150cd728d9ff5955b42d6a643ac10c",
     "rust-std-1.45.0-x86_64-apple-darwin": "e3ac5a3efc106ea13687aa1231609a5d61b1874f4b3a2f68b0e0ad70c89a2364",
     "rust-std-1.45.0-x86_64-unknown-freebsd": "68b28ad5488bfb051589c7079bdfa396aa42c29d463a5622fb5eb9d6ecc4a8e6",
     "rust-std-1.45.0-x86_64-unknown-linux-gnu": "7ab1dbcdeab16dfea1ed024675e60429db9719f03648e6a09662de72b4ff730f",
     "rust-std-1.46.0-aarch64-unknown-linux-gnu": "eaa7cfd73e96b6ce03498398f4bd9ded73870fe3c5db980038a4863c37157597",
     "rust-std-1.46.0-wasm32-unknown-unknown": "0ef3344aff8ae3f2065ed8f15daa73514a26f934e160cb6974d43a8231fcc090",
+    "rust-std-1.46.0-wasm32-wasi": "44a37dfe4398e1c120a199b2ebbe86838171c38a29a0f76e10ede00bf1aeb16f",
     "rust-std-1.46.0-x86_64-apple-darwin": "8c897982bc38c9528b448fe551f089fee7716e692dece98052f4459ccc6e591c",
     "rust-std-1.46.0-x86_64-unknown-freebsd": "e37c06bbe2bf2501675101787388ab87d510ef80f2e091be3f50fc5d019add1e",
     "rust-std-1.46.0-x86_64-unknown-linux-gnu": "ac04aef80423f612c0079829b504902de27a6997214eb58ab0765d02f7ec1dbc",
     "rust-std-1.47.0-aarch64-unknown-linux-gnu": "0019c302a0a02d8a9e40c3bcdd5a31b9b2704161563d72df3572521989182b0c",
     "rust-std-1.47.0-wasm32-unknown-unknown": "b0d19ceb2b56105ee3407bdecaa779747abb1574990632e53a2aba681e964187",
+    "rust-std-1.47.0-wasm32-wasi": "0eab479faac83b9352af04ba4dea376fdeade3101f5e912f40ee3c93e32d1317",
     "rust-std-1.47.0-x86_64-apple-darwin": "6b86bcdad5a6eff87a67b6387051d7f10a48e088b8f92d76869d201500b9ce13",
     "rust-std-1.47.0-x86_64-unknown-freebsd": "80f5dee782bd74b41c55a676c624ce2260ab54c834102c90ea54e0c5e7e513c6",
     "rust-std-1.47.0-x86_64-unknown-linux-gnu": "17ecad27d96b331608e4a96dfa3cad05ccb2ccecb888894ed35054e0d1f5207f",

rust/platform/cpu/BUILD

@@ -0,0 +1,5 @@
+constraint_value(
+    name = "wasm32",
+    constraint_setting = "@platforms//cpu",
+    visibility = ["//visibility:public"],
+)

rust/platform/os/BUILD

@@ -0,0 +1,11 @@
+constraint_value(
+    name = "unknown",
+    constraint_setting = "@platforms//os",
+    visibility = ["//visibility:public"],
+)
+
+constraint_value(
+    name = "wasi",
+    constraint_setting = "@platforms//os",
+    visibility = ["//visibility:public"],
+)

rust/platform/platform.bzl

@@ -35,6 +35,7 @@ _SUPPORTED_T2_PLATFORM_TRIPLES = [
     "powerpc-unknown-linux-gnu",
     "s390x-unknown-linux-gnu",
     "wasm32-unknown-unknown",
+    "wasm32-wasi",
     "x86_64-apple-ios",
     "x86_64-linux-android",
     "x86_64-unknown-freebsd",
@@ -86,15 +87,19 @@ def declare_config_settings():
             constraint_values = triple_to_constraint_set(triple),
         )
 
-    native.constraint_value(
-        name = "wasm32",
-        constraint_setting = "@platforms//cpu",
+    native.platform(
+        name = "wasm",
+        constraint_values = [
+            "@io_bazel_rules_rust//rust/platform/cpu:wasm32",
+            "@io_bazel_rules_rust//rust/platform/os:unknown",
+        ],
     )
 
     native.platform(
-        name = "wasm",
+        name = "wasi",
         constraint_values = [
-            "@io_bazel_rules_rust//rust/platform:wasm32",
+            "@io_bazel_rules_rust//rust/platform/cpu:wasm32",
+            "@io_bazel_rules_rust//rust/platform/os:wasi",
         ],
     )
 

rust/platform/triple_mappings.bzl

@@ -19,6 +19,7 @@ _CPU_ARCH_TO_BUILTIN_PLAT_SUFFIX = {
     "le32": None,
     "mips": None,
     "mipsel": None,
+    "wasm32": None,
 }
 
 # Systems that map to a "@platforms//os entry
@@ -30,6 +31,8 @@ _SYSTEM_TO_BUILTIN_SYS_SUFFIX = {
     "ios": "ios",
     "android": "android",
     "emscripten": None,
+    "unknown": None,
+    "wasi": None,
     "nacl": None,
     "bitrig": None,
     "dragonfly": None,
@@ -49,6 +52,7 @@ _SYSTEM_TO_BINARY_EXT = {
     # generated extension for the wasm target, similarly to the
     # windows target
     "unknown": ".wasm",
+    "wasi": ".wasm",
 }
 
 _SYSTEM_TO_STATICLIB_EXT = {
@@ -59,6 +63,7 @@ _SYSTEM_TO_STATICLIB_EXT = {
     "windows": ".lib",
     "emscripten": ".js",
     "unknown": "",
+    "wasi": "",
 }
 
 _SYSTEM_TO_DYLIB_EXT = {
@@ -69,6 +74,7 @@ _SYSTEM_TO_DYLIB_EXT = {
     "windows": ".dll",
     "emscripten": ".js",
     "unknown": ".wasm",
+    "wasi": ".wasm",
 }
 
 # See https://github.com/rust-lang/rust/blob/master/src/libstd/build.rs
@@ -109,6 +115,7 @@ _SYSTEM_TO_STDLIB_LINKFLAGS = {
     # I am not sure which is the common configuration or how we encode it as a link flag.
     "cloudabi": ["-lunwind", "-lc", "-lcompiler_rt"],
     "unknown": [],
+    "wasi": [],
 }
 
 def cpu_arch_to_constraints(cpu_arch):
@@ -140,6 +147,17 @@ def abi_to_constraints(abi):
     return []
 
 def triple_to_system(triple):
+    """Returns a system name for a given platform triple
+
+    Args:
+        triple (str): A platform triple. eg: `x86_64-unknown-linux-gnu`
+
+    Returns:
+        str: A system name
+    """
+    if triple == "wasm32-wasi":
+        return "wasi"
+
     component_parts = triple.split("-")
     if len(component_parts) < 3:
         fail("Expected target triple to contain at least three sections separated by '-'")
@@ -167,6 +185,11 @@ def triple_to_constraint_set(triple):
     Returns:
         list: A list of constraints (each represented by a list of strings)
     """
+    if triple == "wasm32-wasi":
+        return ["@io_bazel_rules_rust//rust/platform/cpu:wasm32", "@io_bazel_rules_rust//rust/platform/os:wasi"]
+    if triple == "wasm32-unknown-unknown":
+        return ["@io_bazel_rules_rust//rust/platform/cpu:wasm32", "@io_bazel_rules_rust//rust/platform/os:unknown"]
+
     component_parts = triple.split("-")
     if len(component_parts) < 3:
         fail("Expected target triple to contain at least three sections separated by '-'")
@@ -179,9 +202,6 @@ def triple_to_constraint_set(triple):
     if len(component_parts) == 4:
         abi = component_parts[3]
 
-    if cpu_arch == "wasm32":
-        return ["@io_bazel_rules_rust//rust/platform:wasm32"]
-
     constraint_set = []
     constraint_set += cpu_arch_to_constraints(cpu_arch)
     constraint_set += vendor_to_constraints(vendor)

rust/private/dummy_cc_toolchain/BUILD

@@ -7,7 +7,7 @@ dummy_cc_toolchain(name = "dummy_cc_wasm32")
 # TODO([email protected]): Need to support linking C code to rust code when compiling for wasm32.
 toolchain(
     name = "dummy_cc_wasm32_toolchain",
-    target_compatible_with = ["@io_bazel_rules_rust//rust/platform:wasm32"],
+    target_compatible_with = ["@io_bazel_rules_rust//rust/platform/cpu:wasm32"],
     toolchain = ":dummy_cc_wasm32",
     toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
 )

rust/repositories.bzl

@@ -74,7 +74,7 @@ def rust_repositories(
     rust_repository_set(
         name = "rust_linux_x86_64",
         exec_triple = "x86_64-unknown-linux-gnu",
-        extra_target_triples = ["wasm32-unknown-unknown"],
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
         version = version,
         iso_date = iso_date,
         rustfmt_version = rustfmt_version,
@@ -86,7 +86,7 @@ def rust_repositories(
     rust_repository_set(
         name = "rust_linux_aarch64",
         exec_triple = "aarch64-unknown-linux-gnu",
-        extra_target_triples = ["wasm32-unknown-unknown"],
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
         version = version,
         iso_date = iso_date,
         rustfmt_version = rustfmt_version,
@@ -98,7 +98,7 @@ def rust_repositories(
     rust_repository_set(
         name = "rust_darwin_x86_64",
         exec_triple = "x86_64-apple-darwin",
-        extra_target_triples = ["wasm32-unknown-unknown"],
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
         version = version,
         iso_date = iso_date,
         rustfmt_version = rustfmt_version,
@@ -110,7 +110,7 @@ def rust_repositories(
     rust_repository_set(
         name = "rust_freebsd_x86_64",
         exec_triple = "x86_64-unknown-freebsd",
-        extra_target_triples = ["wasm32-unknown-unknown"],
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
         version = version,
         iso_date = iso_date,
         rustfmt_version = rustfmt_version,
@@ -122,7 +122,7 @@ def rust_repositories(
     rust_repository_set(
         name = "rust_windows_x86_64",
         exec_triple = "x86_64-pc-windows-msvc",
-        extra_target_triples = ["wasm32-unknown-unknown"],
+        extra_target_triples = ["wasm32-unknown-unknown", "wasm32-wasi"],
         version = version,
         iso_date = iso_date,
         rustfmt_version = rustfmt_version,

util/fetch_shas_TARGETS.txt

@@ -3,3 +3,4 @@ x86_64-unknown-freebsd
 x86_64-unknown-linux-gnu
 x86_64-apple-darwin
 wasm32-unknown-unknown
+wasm32-wasi