initial commit

.gitattributes

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+* text=auto

.github/workflows/test.yml

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+name: Test
+
+on:
+  push:
+  pull_request:
+  schedule:
+    # Weekly, at 5:45 AM on Friday (somewhat randomly chosen).
+    - cron: '45 5 * * 5'
+  workflow_dispatch:
+
+jobs:
+  test:
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [x86, x64]
+        cygwin: [0, 1]
+        os: [ubuntu-18.04, windows-2019, windows-2016]
+
+        include:
+          # Prettier run names.
+          - {os: ubuntu-18.04, name: Ubuntu}
+          - {os: windows-2019, name: Windows Server 2019}
+          - {os: windows-2016, name: Windows Server 2016}
+          - {cygwin: 1, name: Cygwin}
+        exclude:
+          # No Cygwin on Ubuntu.
+          - {os: ubuntu-18.04, cygwin: 1}
+          # Cygwin is the same on Windows Server 2016 & 2019.
+          - {os: windows-2016, cygwin: 1}
+
+    runs-on: '${{ matrix.os }}'
+
+    name: '${{ matrix.name }} / ${{ matrix.platform }}'
+
+    defaults:
+      run:
+        shell: pwsh
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Clean up PATH
+        uses: egor-tensin/cleanup-path@v1
+        if: runner.os == 'Windows'
+
+      - name: Install Cygwin
+        uses: egor-tensin/setup-cygwin@master
+        with:
+          platform: '${{ matrix.platform }}'
+        if: matrix.cygwin
+
+      - name: Set up Clang
+        id: setup
+        uses: ./
+        with:
+          platform: '${{ matrix.platform }}'
+          cygwin: '${{ matrix.cygwin }}'
+
+      - name: Build foo.exe
+        run: |
+          $flags = @()
+          if ('${{ matrix.platform }}' -eq 'x86') {
+              $flags += '-m32'
+          }
+          $flags += @(
+              '-x', 'c++',
+              '-std=c++14',
+              '-o', 'foo',
+              'foo.cpp',
+              '-lstdc++'
+          )
+          if ('${{ runner.os }}' -eq 'Linux') {
+              $flags += '-lpthread'
+          }
+          & '${{ steps.setup.outputs.clangxx }}' $flags
+          & (Join-Path . foo)

LICENSE.txt

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+MIT License
+
+Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

action.yml

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+name: Install Clang
+description: Install Clang & LLVM
+
+inputs:
+  platform:
+    description: Target platform
+    required: false
+    default: x64
+  cygwin:
+    description: Install inside Cygwin
+    required: false
+    default: 0
+
+outputs:
+  clang:
+    description: clang executable name or path
+    value: '${{ steps.setup.outputs.clang }}'
+  clangxx:
+    description: clang++ executable name or path
+    value: '${{ steps.setup.outputs.clangxx }}'
+
+runs:
+  using: composite
+  steps:
+    - id: setup
+      run: |
+        New-Variable os -Value '${{ runner.os }}' -Option Constant
+
+        New-Variable linux_host -Value ($os -eq 'Linux') -Option Constant
+        New-Variable cygwin_host -Value ('${{ inputs.cygwin }}' -eq '1') -Option Constant
+        New-Variable windows_host -Value ($os -eq 'Windows' -and !$cygwin) -Option Constant
+
+        New-Variable x64 -Value ('${{ inputs.platform }}' -eq 'x64') -Option Constant
+
+        function Locate-Choco {
+            $path = Get-Command 'choco' -ErrorAction SilentlyContinue
+            if ($path) {
+                $path.Path
+            } else {
+                Join-Path ${env:ProgramData} 'chocolatey' 'bin' 'choco'
+            }
+        }
+
+        if ($linux_host) {
+            sudo apt update
+            if ($x64) {
+                sudo apt install -y clang g++
+            } else {
+                sudo apt install -y clang g++-multilib
+            }
+
+            echo "::set-output name=clang::clang"
+            echo "::set-output name=clangxx::clang++"
+        } elseif ($cygwin_host) {
+            if (!$x64) {
+                echo @'
+        ::warning ::
+        32-bit-targeting Clang is unavailable on 64-bit Cygwin.
+        Please use 32-bit Cygwin instead.
+        If you _are_ using 32-bit Cygwin, please ignore this message.
+        '@
+            }
+            $choco = Locate-Choco
+
+            # IDK why, but without libiconv-devel, even a "Hello, world!"
+            # C++ app cannot be compiled as of December 2020.
+            # Also, libstdc++ is required, and for simplicity's sake, gcc-g++
+            # is installed.
+            & $choco install -y --no-progress --source=cygwin clang libiconv-devel gcc-g++
+
+            # clang/clang++ are symlinks on Cygwin, pointing to clang-VERSION.exe.
+            $clang = cygpath.exe -wa (readlink.exe --canonicalize-existing /usr/bin/clang)
+            $clangxx = cygpath.exe -wa (readlink.exe --canonicalize-existing /usr/bin/clang++)
+
+            echo "::set-output name=clang::$clang"
+            echo "::set-output name=clangxx::$clangxx"
+        } elseif ($windows_host) {
+            $choco = Locate-Choco
+
+            & $choco install -y --no-progress llvm
+            echo (Join-Path $env:ProgramFiles LLVM bin) >> $env:GITHUB_PATH
+
+            echo "::set-output name=clang::clang"
+            echo "::set-output name=clangxx::clang++"
+        } else {
+            throw "Sorry, installing Clang is unsupported on $os"
+        }
+      shell: pwsh
+
+branding:
+  icon: star
+  color: green

foo.cpp

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+#include <array>
+#include <cstddef>
+#include <exception>
+#include <functional>
+#include <iostream>
+#include <mutex>
+#include <thread>
+
+namespace {
+
+struct Counter {
+    std::mutex mtx;
+    std::size_t impl = 0;
+};
+
+void do_something(Counter& counter) {
+    std::lock_guard<std::mutex> lck{counter.mtx};
+    ++counter.impl;
+    std::cout << "Doing something #" << counter.impl << '\n';
+}
+
+}
+
+int main() {
+    try {
+        Counter counter;
+        std::array<std::thread, 3> workers;
+        for (auto& worker : workers) {
+            worker = std::thread{&do_something, std::ref(counter)};
+        }
+        for (auto& worker : workers) {
+            worker.join();
+        }
+    } catch (const std::exception& e) {
+        std::cerr << e.what() << '\n';
+        return 1;
+    }
+    return 0;
+}