The `CONTROL` file contains metadata about the port. The syntax is based on [the Debian `control` format][debian] although we only support the subset of fields documented here.
The first paragraph in a `CONTROL` file is the Source paragraph. It must have a `Source`, `Version`, and `Description` field. The full set of fields is documented below.
When adding new ports be aware that the name may conflict with other projects that are not a part of vcpkg. For example `json` conflicts with too many other projects so you should add a scope to the name such as `taocpp-json` to make it unique. Verify there are no conflicts on a search engine as well as on other package collections.
This field is an alphanumeric string that may also contain `.`, `_`, or `-`. No attempt at ordering versions is made; all versions are treated as bit strings and are only evaluated for equality.
1. If the port follows a scheme like `va.b.c`, we remove the leading `v`. In this case, it becomes `a.b.c`.
2. If the port includes its own name in the version like `curl-7_65_1`, we remove the leading name: `7_65_1`
For rolling-release ports, we use the date that the _commit was accessed by you_, formatted as `YYYY-MM-DD`. Stated another way: if someone had a time machine and went to that date, they would see this commit as the latest master.
Then if you update the source version today, you should give it version `2019-06-01`.
#### Port-Version
The version of the port.
This field is a non-negative integer. It allows one to version the port file separately from the version of the underlying library; if you make a change to a port, without changing the underlying version of the library, you should increment this field by one (starting at `0`, which is equivalent to no `Port-Version` field). When the version of the underlying library is upgraded, this field should be set back to `0` (i.e., delete the `Port-Version` field).
By convention the first line of the description is a summary of the library. An optional detailed description follows. The detailed description can be multiple lines, all starting with whitespace.
Comma separated list of vcpkg ports the library has a dependency on.
Vcpkg does not distinguish between build-only dependencies and runtime dependencies. The complete list of dependencies needed to successfully use the library should be specified.
*For example: websocketpp is a header only library, and thus does not require any dependencies at install time. However, downstream users need boost and openssl to make use of the library. Therefore, websocketpp lists boost and openssl as dependencies*
If the port is dependent on optional features of another library those can be specified using the `portname[featurelist]` syntax. If the port does not require any features from the dependency, this should be specified as `portname[core]`.
Dependencies can be filtered based on the target triplet to support differing requirements. These filters use the same syntax as the Supports field below and are surrounded in parentheses following the portname and feature list.
Expression that evaluates to true when the port is expected to build successfully for a triplet.
Currently, this field is only used in the CI testing to skip ports. In the future, this mechanism is intended to warn users in advance that a given install tree is not expected to succeed. Therefore, this field should be used optimistically; in cases where a port is expected to succeed 10% of the time, it should still be marked "supported".
The grammar for the supports expression uses standard operators:
-`!expr` - negation
-`expr|expr` - or (`||` is also supported)
-`expr&expr` - and (`&&` is also supported)
-`(expr)` - grouping/precedence
The predefined expressions are computed from standard triplet settings:
-`x64` - `VCPKG_TARGET_ARCHITECTURE` == `"x64"`
-`x86` - `VCPKG_TARGET_ARCHITECTURE` == `"x86"`
-`arm` - `VCPKG_TARGET_ARCHITECTURE` == `"arm"` or `VCPKG_TARGET_ARCHITECTURE` == `"arm64"`
Multiple optional features can be specified in the `CONTROL` files. It must have a `Feature` and `Description` field. It can optionally have a `Build-Depends` field. It must be separated from other paragraphs by one or more empty lines.
On installation the dependencies from all selected features are combined to produce the full dependency list for the build. This field follows the same syntax as `Build-Depends` in the Source Paragraph.
