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+<a href="https://github.com/ilammy/msvc-dev-cmd"><img alt="GitHub Actions status" src="https://github.com/ilammy/msvc-dev-cmd/workflows/msvc-dev-cmd/badge.svg"></a>
+
+# msvc-dev-cmd
+
+[GitHub Action](https://github.com/features/actions) for configuring Developer Command Prompt for Microsoft Visual C++.
+
+This sets up the environment for compiling C/C++ code from command line.
+
+Supports Windows. Does nothing on Linux and macOS.
+
+## Example usage
+
+Basic usage for default compilation settings is like this:
+
+```yaml
+jobs:
+  test:
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ilammy/msvc-dev-cmd@v1
+      - name: Build something requiring CL.EXE
+        run: |
+          cmake -G "NMake Makefiles" .
+          nmake
+      # ...
+```
+
+If you want something non-default,
+like using a specific version of Visual Studio,
+or cross-compling for a differen target,
+you will need to configure those settings via inputs:
+
+```yaml
+jobs:
+  test:
+    # Run a job for each of the specified target architectures:
+    strategy:
+      matrix:
+        arch:
+          - amd64
+          - amd64_x86
+          - amd64_arm64
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: ${{ matrix.arch }}
+      - name: Build something requiring CL.EXE
+        run: |
+          cmake -G "NMake Makefiles" .
+          nmake
+      # ...
+```
+
+## Inputs
+
+- `arch` – target architecture
+  - native compilation:
+    - `x64` (default) or its synonyms: `amd64`, `win64`, `x86_64`, `x86-64`
+    - `x86` or its synonyms: `win32`
+  - cross-compilation: `x86_amd64`, `x86_arm`, `x86_arm64`, `amd64_x86`, `amd64_arm`, `amd64_arm64`
+- `sdk` – Windows SDK to use
+  - do not specify to use the default SDK
+  - or specify full Windows 10 SDK number (e.g, `10.0.10240.0`)
+  - or write `8.1` to use Windows 8.1 SDK
+- `toolset` – select VC++ compiler toolset version
+  - do not specify to use the default toolset
+  - `14.0` for VC++ 2015 Compiler Toolset
+  - `14.XX` for the latest 14.XX toolset installed (e.g, `14.11`)
+  - `14.XX.YYYYY` for a specific full version number (e.g, `14.11.25503`)
+- `uwp` – set `true` to build for Universal Windows Platform (i.e., for Windows Store)
+- `spectre` – set `true` to use Visual Studio libraries with [Spectre](https://meltdownattack.com) mitigations
+
+## Caveats
+
+### Name conflicts with `shell: bash`
+
+Using `shell: bash` in Actions may shadow some of the paths added by MSVC.
+In particular, `link.exe` (Microsoft C linker) is prone to be shadowed by `/usr/bin/link` (GNU filesystem link tool).
+
+Unfortunately, this happens because GitHub Actions unconditionally *prepend* GNU paths when `shell: bash` is used,
+on top of any paths set by `msvc-dev-cmd`, every time at the start of each new step.
+Hence, there aren't many non-destructive options here.
+
+If you experience compilation errors where `link` complains about unreasonable command-line arguments,
+“extra operand *something-something*” – that's probably it.
+Recommended workaround is to remove `/usr/bin/link` if that interferes with your builds.
+If this is not acceptable, please file an issue, then we'll figure out something better.
+
+### Reconfiguration
+
+You can invoke `ilammy/msvc-dev-cmd` multiple times during your jobs with different inputs
+to reconfigure the environment for building with different settings
+(e.g., to target multiple architectures).
+
+```yaml
+jobs:
+  release:
+    steps:
+      # ...
+      - name: Configure build for amd64
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: amd64
+
+      - run: build # (for amd64)
+
+      - name: Configure build for x86
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: amd64_x86
+
+      - run: build # (for x86)
+
+      - name: Configure build for ARM64
+        uses: ilammy/msvc-dev-cmd@v1
+        with:
+          arch: amd64_arm64
+
+      - run: build # (for ARM64)
+
+      # ...
+```
+
+This mostly works but it's not really recommended
+since Developer Command Prompt was not meant for recursive reconfiguration.
+That said, if it does not work for you, please file an issue.
+
+Consider using [`strategy.matrix`](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjob_idstrategymatrix)
+to execute different build configuration in parallel, independent environments.
+
+## License
+
+MIT, see [LICENSE](LICENSE).