package.hocon

// A C standard library written in sysl, for machines that have none.
//
// It exists for two consumers. keel, the research kernel at `github.com/sysl-lang/keel`, ports C
// programs through it; and a bare-metal board, where sysl's freestanding targets carry no libc, so a
// vendored C package that includes `<string.h>` or `<stdlib.h>` has nothing to compile against
// until something supplies the header and the symbols behind it.
//
// This is the block a consumer writes to reach it:
//
//     dependencies {
//       cstd { git = "github.com/sysl-lang/cstd", version = "0.1.3", if = "!libc" }
//     }
//
// `if = "!libc"` takes cstd only where the machine has no C library under the program: on a board
// its headers become the C system headers of every package below, and its sysl satisfies the
// symbols; on a hosted machine the entry is dropped and the real libc is the one compiled against
// and linked. The coordinate names the package, `cstd`; the module is `sh.sysl.cstd`.

package {
  name    = "cstd"
  version = "0.1.3"
}

// `include/` is the C standard library's headers. Where the target has no libc, every dependent's C
// is compiled with the machine's own header search taken away and these in its place; clang's own
// freestanding headers (`stddef.h`, `stdint.h`, `stdbool.h`, `limits.h`) stay. Where the target has
// a libc they are not used at all.
c {
  libc { export = ["include"], libc = true }
}

// **There is deliberately no `requires` block.** Everything here is arithmetic over bytes a caller
// handed in, or, on a bare-metal target, a weak default a board replaces: the operating-system calls
// answering ENOSYS, an allocator growing through whatever `sbrk` the link holds, and exits that trap.
// Nothing asks an operating system for anything itself.