add basic build workflow

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: Build
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        config:
+          - runs-on: ubuntu-22.04
+            os: linux
+            arch: x86_64
+          - runs-on: macos-14
+            os: macos
+            arch: arm64
+          - runs-on: macos-13
+            os: macos
+            arch: x86_64
+    runs-on: ${{ matrix.config.runs-on }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/checkout@v4
+        with:
+          repository: llvm/llvm-project
+          path: llvm-project
+      - name: Install dependencies
+        run: ./scripts/install-${{ matrix.config.os }}.sh
+      - name: Build clang-format
+        run: ./scripts/build-${{ matrix.config.os }}.sh
+      - name: Upload binary
+        uses: actions/upload-artifact@v4
+        with:
+          name: clang-format-${{ matrix.config.os }}-${{ matrix.config.arch }}
+          path: llvm-project/build/bin/clang-format

scripts/build-linux.sh

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+#!/bin/bash
+
+set -e
+
+mkdir llvm-project/build
+cd llvm-project/build
+cmake -G Ninja -DCMAKE_BUILD_TYPE=MinSizeRel -DLLVM_BUILD_STATIC=true -DLLVM_ENABLE_PROJECTS=clang ../llvm
+ninja clang-format
+strip bin/clang-format

scripts/build-macos.sh

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+#!/bin/bash
+
+set -e
+
+mkdir llvm-project/build
+cd llvm-project/build
+cmake -G Ninja -DCMAKE_BUILD_TYPE=MinSizeRel -DLLVM_ENABLE_PROJECTS=clang ../llvm
+ninja clang-format
+strip bin/clang-format

scripts/install-linux.sh

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+#!/bin/bash
+
+set -e
+
+sudo apt-get update
+sudo apt-get install -y ninja-build

scripts/install-macos.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+set -e
+
+brew install ninja