WASI support for Phobos

.github/actions/5a-wasi/action.yml

@@ -1,4 +1,4 @@
-name: "WASI: Cross-compile druntime incl. test runners, install libs + .conf, run druntime unittests"
+name: "WASI: Cross-compile druntime & phobos incl. test runners, install libs + .conf, run druntime & phobos unittests"
 inputs:
   os:
     required: true
@@ -7,7 +7,7 @@ inputs:
 runs:
   using: composite
   steps:
-    - name: Cross-compile druntime incl. test runners & install libs + .conf
+    - name: Cross-compile druntime & phobos incl. test runners & install libs + .conf
       shell: bash
       run: |
         set -eux
@@ -34,7 +34,6 @@ runs:
           --testrunners \
           CMAKE_INSTALL_PREFIX="$PWD/install" \
           RT_CONF_TRIPLE_REGEX="$arch-.*-$os" \
-          PHOBOS2_DIR= \
           CMAKE_TOOLCHAIN_FILE="$PWD/wasi-sdk/share/cmake/wasi-sdk${toolchain_suffix}.cmake" \
           BUILD_LTO_LIBS=ON
 
@@ -48,6 +47,26 @@ runs:
         ../wasmtime/wasmtime -W exceptions ./druntime-test-runner-debug
         ../wasmtime/wasmtime -W exceptions ./druntime-test-runner
 
+    - name: Run phobos unittests
+      shell: bash
+      run: |
+        set -eux
+        cd ../ldc-build-runtime.${{ inputs.os }}-${{ inputs.arch }}
+
+        mkdir -p testrunner_tmpdir/tmp
+
+        export WASMTIME_BACKTRACE_DETAILS=1
+
+        for testrunner in ./phobos2-test-runner*; do
+          ../wasmtime/wasmtime -W exceptions \
+            --dir testrunner_tmpdir::/ \
+            --dir /usr/share/zoneinfo::/tz \
+            --env TZDIR=/tz/ \
+            --env HOME=/tmp \
+            -S inherit-network \
+            $testrunner
+        done
+
     - name: Run `importc_compare`
       shell: bash
       run: |

.github/workflows/main.yml

@@ -407,12 +407,12 @@ jobs:
         uses: ./.github/actions/1a-setup-wasi
       - name: Build bootstrap LDC
         uses: ./.github/actions/2-build-bootstrap
-      - name: 'WASIp1: Cross-compile druntime incl. test runners & run druntime unittests'
+      - name: 'WASIp1: Cross-compile druntime & phobos incl. test runners & run druntime & phobos unittests'
         uses: ./.github/actions/5a-wasi
         with:
           os: wasip1
           arch: ${{ matrix.arch }}
-      - name: 'WASIp2: Cross-compile druntime incl. test runners & run druntime unittests'
+      - name: 'WASIp2: Cross-compile druntime & phobos incl. test runners & run druntime & phobos unittests'
         uses: ./.github/actions/5a-wasi
         with:
           os: wasip2
@@ -432,13 +432,13 @@ jobs:
           cd ../bootstrap-ldc
           tar xf ${{ github.workspace }}/artifacts/*-addon-*.tar.xz
           # generate hello.d
-          echo 'void main() { import core.stdc.stdio; printf("Hello world, %d bits\n", size_t.sizeof * 8); }' > hello.d
+          echo 'void main() { import std.stdio; writefln!"Hello world, %d bits"(size_t.sizeof * 8); }' > hello.d
           # put WASI-SDK clang onto PATH
           export PATH="$PWD/../wasi-sdk/bin:$PATH"
           # build & run hello-world
           for os in wasip1 wasip2; do
             # test LTO too
-            for args in "" "-O -flto=full -defaultlib=druntime-ldc-lto"; do
+            for args in "" "-O -flto=full -defaultlib=druntime-ldc-lto,phobos2-ldc-lto"; do
               bin/ldc2 -mtriple=${{ matrix.arch }}-unknown-$os $args hello.d
               ls -l hello.wasm
               ../wasmtime/wasmtime -W exceptions ./hello.wasm

CHANGELOG.md

@@ -5,18 +5,18 @@
   - `-foptimize-nothrow` is the default setting when targeting Windows or WebAssembly, to make hitting https://github.com/ldc-developers/ldc/issues/3504 much less likely.
 - Support for [LLVM 22](https://releases.llvm.org/22.1.0/docs/ReleaseNotes.html). The prebuilt packages use v22.1.8. (#5097, #5102, #5172)
 - Minimum LLVM version raised to 18. (#5094)
+- DRuntime and Phobos now support [WASI](https://github.com/WebAssembly/WASI) preview levels 1 and 2, based on [`wasi-libc`](https://github.com/WebAssembly/wasi-libc). Two caveats being that WASI is strictly single-threaded (currently), and that fibers are unavailable. (#5186, #5229, #5230, #5242)
 - New prebuilt **addon packages** (`ldc2-*-addon-<target OS>.tar.xz`) for simple cross-compilation. Simply unpack them directly into your LDC installation directory, and then cross-compile via `-mtriple=…` (or `dub --target=…`): (#5240)
   - Windows: `x86_64-windows-msvc`, `i686-windows-msvc`; no SDK required.
   - Android: `aarch64-linux-android30`, `armv7a-linux-androideabi29`, `x86_64-linux-android29`, `i686-linux-android29`; needs an [Android NDK](https://developer.android.com/ndk/downloads) (r27) and its `toolchains/llvm/prebuilt/*/bin/` dir in your PATH.
-  - WASI: `wasm32-unknown-wasip1`, `wasm32-unknown-wasip2`; needs a [WASI SDK](https://github.com/webassembly/wasi-sdk) and its `bin/` dir in your PATH. Phobos support is coming, currently druntime only. (#5207)
+  - WASI: `wasm32-unknown-wasip1`, `wasm32-unknown-wasip2`; needs a [WASI SDK](https://github.com/webassembly/wasi-sdk) and its `bin/` dir in your PATH. (#5207, #5242)
 - The `@ldc.attributes.restrict` UDA is now supported for dynamic-array parameters too. Builtin array ops (`c[] = a[] * b[]` etc.) use it, enabling auto-vectorization. Note that for such array ops, the dlang spec prescribes that the slice on the left and any slices on the right must not overlap (https://dlang.org/spec/arrays.html#array-operations), and this knowledge is now used by the optimizer; e.g., `x[] *= x[]` is invalid. (#5148, #5168, #5176)
 - DMD-style inline assembly: `asm { naked; }` is now much less of a special case wrt. codegen - such naked functions are now emitted as if `asm { naked; }` was replaced with the `@naked` function UDA. IR-wise, they are not emitted as module-level asm blobs anymore, but regular IR functions. This should lift a few former `asm { naked; }`-specific restrictions and fixed at least one LTO issue. (#5041)
 - **dcompute**: Added support for Native device code Embedding (PTX and SPIR-V) into the host executable's `.rodata` section. (#5140)
 - WebAssembly:
   - The default `-fvisibility` setting was changed to `hidden`, like clang, so that only explicit `export`ed symbols are not hidden. And `-L--export-dynamic` isn't used by default for linking anymore either; add it manually to export all non-hidden symbols, as for normal Posix targets. The net effect is that the size of linked wasm binaries shrinks significantly by default. (#5216)
   - Exceptions are now supported. Currently, using D and C++ exceptions are mutually exclusive. If linking in DRuntime, you cannot link in C++ code relying on `libunwind` (exceptions), due to the hacks required to convince LLVM to use D's EH personality. A future LLVM release may help remove the constraint. (#5162)
   - In order to allow the GC to function correctly, a new pass is run after optimizations, to spill potential pointers onto the "stack". This pass is enabled by default for all Wasm targets, but can be disabled with `-betterC` or the new `-disable-wasm-ptrs-spill`. (#5178)
-- DRuntime now supports [WASI](https://github.com/WebAssembly/WASI) preview levels 1 and 2, based on [`wasi-libc`](https://github.com/WebAssembly/wasi-libc). Two caveats being that WASI is strictly single-threaded (currently), and that fibers are unavailable. (#5186, #5229, #5230)
 - A new `-fno-moduleinfo-localclasses` switch has been added. This disables populating `ModuleInfo.localClasses` for each module. This can help eliminate/strip more dead-code (thus decreasing binary sizes), but breaks `Object.factory` and any other code relying on iterating over said `localClasses`. Enabled by default for Wasm targets. (#5224, #5231)
 - Predefined version `LDC_LLVM_*` now only contains the LLVM major version, i.e., former `version (LDC_LLVM_1801)` with LLVM v18.1 is now `version (LDC_LLVM_18)`. Use `ldc.intrinsics.LLVM_version` for backwards compatibility if really needed. (#5109)
 

runtime/druntime/src/core/sys/posix/unistd.d

@@ -114,15 +114,9 @@ else
 
 version (CRuntime_WASI)
 {
-    version (WASI_EMULATED_GETPID)
-        pid_t   getpid() @trusted;
-    else
-        deprecated("WASI lacks process identifiers; to enable emulation of"~
-                   " the `getpid` function using a placeholder value, which"~
-                   " doesn't reflect the host PID of the program, compile"~
-                   " with --d-version=WASI_EMULATED_GETPID and link with"~
-                   " -lwasi-emulated-getpid")
-        pid_t   getpid() @trusted;
+    // WASI has no processes, and wasi-libc requires you to jump through hoops
+    // to link this in. We just let D code use it silently.
+    extern(D) pid_t getpid()() @trusted => 42;
 } else
     pid_t   getpid() @trusted;