GCC Configuration

This is an example of writing contracts and generating a configuration for an invocation of the gcc compiler.

Run

nickel export config-gcc.ncl

Contracts

This example defines a couple contracts:

• GccFlag: define valid flags that can be passed to gcc. It demonstrates a use-case where data can be specified in different format: here, a flag is either a simple string like "-Wextra" or a structured value {flag = "W", arg = "extra"}. The contract normalizes the value to a string, so that it appears as such in the output. This contract is illustrative and by no mean exhaustive.
• Path: define a valid /-separated path as a string. In particular, the # sequence is forbidden.
• SharedObjectFile: define a file whose extension is .so.
• OptLevel: optimization level, either 0, 1 or 2.
• Contract: the schema of the end configuration.

Playground

You can try to break any of the previous contracts to see what happens: provide a non supported flag, a path_libc that doesn't end in ".so", and so on. You can do it from the command line, for example:

nickel export config-gcc.ncl -- --override "path_libc=/usr/lib/libc.exe"