Merge pull request #1 from Microsoft/master

Update vcpkg from upstream

1 files changed, 54 insertions, 0 deletions

diff --git a/docs/maintainers/vcpkg_from_github.md b/docs/maintainers/vcpkg_from_github.md
new file mode 100644
index 000000000..cf50dc445
--- /dev/null
+++ b/docs/maintainers/vcpkg_from_github.md
@@ -0,0 +1,54 @@
+# vcpkg_from_github
+
+Download and extract a project from GitHub. Enables support for `install --head`.
+
+## Usage:
+```cmake
+vcpkg_from_github(
+    OUT_SOURCE_PATH <SOURCE_PATH>
+    REPO <Microsoft/cpprestsdk>
+    [REF <v2.0.0>]
+    [SHA512 <45d0d7f8cc350...>]
+    [HEAD_REF <master>]
+)
+```
+
+## Parameters:
+### OUT_SOURCE_PATH
+Specifies the out-variable that will contain the extracted location.
+
+This should be set to `SOURCE_PATH` by convention.
+
+### REPO
+The organization or user and repository on GitHub.
+
+### REF
+A stable git commit-ish (ideally a tag) that will not change contents. **This should not be a branch.**
+
+For repositories without official releases, this can be set to the full commit id of the current latest master.
+
+If `REF` is specified, `SHA512` must also be specified.
+
+### SHA512
+The SHA512 hash that should match the archive (https://github.com/${REPO}/archive/${REF}.tar.gz).
+
+This is most easily determined by first setting it to `1`, then trying to build the port. The error message will contain the full hash, which can be copied back into the portfile.
+
+### HEAD_REF
+The unstable git commit-ish (ideally a branch) to pull for `--head` builds.
+
+For most projects, this should be `master`. The chosen branch should be one that is expected to be always buildable on all supported platforms.
+
+## Notes:
+At least one of `REF` and `HEAD_REF` must be specified, however it is preferable for both to be present.
+
+This exports the `VCPKG_HEAD_VERSION` variable during head builds.
+
+## Examples:
+
+* [cpprestsdk](https://github.com/Microsoft/vcpkg/blob/master/ports/cpprestsdk/portfile.cmake)
+* [ms-gsl](https://github.com/Microsoft/vcpkg/blob/master/ports/ms-gsl/portfile.cmake)
+* [beast](https://github.com/Microsoft/vcpkg/blob/master/ports/beast/portfile.cmake)
+
+## Source
+[scripts/cmake/vcpkg_from_github.cmake](https://github.com/Microsoft/vcpkg/blob/master/scripts/cmake/vcpkg_from_github.cmake)