Setup CI

.github/workflows/ci.yml

@@ -0,0 +1,49 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  build-linux-gcc:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v1
+      - name: build all and examples
+        run: |
+          $(CC) -o ls ./examples/ls.c
+          ./ls
+        env:
+          CC: gcc
+          CXX: g++
+  build-linux-clang:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v1
+      - name: build all and examples
+        run: |
+          $(CC) -o ls ./examples/ls.c
+          ./ls
+        env:
+          CC: clang
+          CXX: clang++
+  build-macos:
+    runs-on: macOS-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: build all and examples
+        run: |
+          $(CC) -o ls ./examples/ls.c
+          ./ls
+        env:
+          CC: clang
+          CXX: clang++
+  build-windows-msvc:
+    runs-on: windows-2019
+    steps:
+      - uses: actions/checkout@v1
+        # this runs vcvarsall for us, so we get the MSVC toolchain in PATH.
+      - uses: seanmiddleditch/gha-setup-vsdevenv@master
+      - name: build all and examples
+        shell: cmd
+        # this replaces default PowerShell, which can't fail the build
+        run: |
+          cl.exe examples\ls.c
+          ls.exe