sysl 0.0.158 — a @needs declaration's import and signature are charged to its callers

One capability fix, released as an exception to the bootstrap freeze. It completes 0.0.157's @needs scoping: the import a @needs declaration writes through, and the types its signature names, are now charged to the declaration's callers rather than to its module, as its body already was.

Behaviour changes

Programs that were refused now build. Nothing that built before is refused now.

• A program lacking a capability can import a module whose @needs function imports a gated module, or names one of its types in the signature, as long as it never calls that function. That covers a @no_os program and a project whose target has os = false. The call itself is still refused, at the call. In 0.0.157 the body was already covered, but the file-level import sysl.fs the body used, and a signature such as -> Result[unit, sysl.fs.IoError], still made the whole module require os, so the program was refused at its import line.
• An import or a signature type that an unannotated declaration uses still charges the module, exactly as before.

module store

import sysl.fs

@needs(os)
save(p: string) -> Result[unit, sysl.fs.IoError] = sysl.fs.write_text(p, "x")

plain() -> int = 3

@no_os

import store.plain

print(plain())

In 0.0.157 this program was refused at the import. In 0.0.158 it builds and prints 3. A call to save from it is still refused, at the call.

Fixes

A @needs declaration's import and signature are charged to its callers (11dd0b4)

0.0.157 (8dd5b9a) made what a @needs(...) body reaches its callers' to answer. Two references the body rule did not reach still charged the module:

1. The file-level import the body writes through. An import's edge was recorded with nothing covered, whatever used it. Imports are now recorded as such (EdgeUse.imported) and charged by their uses: GatedModules.effective lifts an import's edge to what every shipping reference along that edge covers. One use from an unannotated declaration covers nothing, so the module is still charged at the import. An import nothing references is charged as written.
2. A gated type named in the declaration's signature. Signatures are resolved by hoisting, generic instantiation, the abstract and opaque-result passes, the signature-visibility check and the drop-return check, all outside the body. Each now runs under DeclTables.inSignature(needs), which covers what the declaration's @needs names. An unannotated signature still charges the module.

Tests

Nine new cases: DeclCapabilityTests (5), TargetCapabilityTests (2, an os = false machine) and NeedsScopeCliTests (2, a real package.hocon at thumbv6m-freestanding).

Now accepted:

• a module whose import is used only inside @needs(os) bodies is importable by a program without os
• a module naming a gated type only in a @needs(os) signature is importable by a program without os
• the same two through a target with os = false, and through package.hocon and --lib

Still refused:

• calling either declaration, at the call only
• an import an unannotated declaration also uses, at the import
• a gated type in an unannotated declaration's signature

Install

brew install sysl-lang/tap/sysl      # or: brew upgrade sysl

The tarballs for macOS arm64, Linux x86_64 and Linux arm64 are attached to this release. The sh.sysl:sysl_3:0.0.158 jars are on GitHub Packages (https://maven.pkg.github.com/sysl-lang/sysl-bootstrap). sysl is not published to Maven Central.

Verification

• Native gate: inherited from the landing gate. 11dd0b4 was gated with the full Native gate: GREEN, 417 suites, 12,331 passed and 0 failed, in 73:44. The tag is 3aadd68, which is 11dd0b4 plus the version bump and nothing else, so the suite was not re-run.
• Warnings census, cleaned: JVM two, JS three, Native three, syslDocJVM one, syslDocNative two. That is the expected count, and every warning belongs to a dependency or is build infrastructure.
• Release tarball: the asset downloaded back from this release, extracted to a scratch prefix and run. sysl --version prints sysl 0.0.158, and sysl-doc is present. The @no_os program above prints 3, where 0.0.157 refused it at its import. The call to save is refused at the call (this reaches 'store.save', which needs 'os', and this module declared '@no_os'). A module naming sysl.fs.IoError in an unannotated signature is still refused at the import.
• GitHub Packages: all four artifacts (the pom, the jar, the sources jar and the javadoc jar) were published.
• brew: brew test sysl passes, and the installed sysl --version prints sysl 0.0.158. The Linux glibc floor, measured in the release run, is 2.34.
• sysl.sh on 0.0.158: 1,418 tests pass with 0 failures. Of those, 1,398 are DocsTests, including the new sentence on reference/modules.md.
• Org sweep with the release tarball's own binary: 79 builds, 73 green under the bare command.
  • 57 ran under sysl test ., 11 under sysl build . and 5 under sysl build-c <dir>.
  • Four repos fail the bare command by design and were run as their READMEs say. freertos against the FreeRTOS-Kernel POSIX port: 84 passed. libpq against a scratch PostgreSQL: 51 passed. quickjs-ng with its include path: 33 passed.
  • pico: build-lib --target thumbv6m-freestanding gets as far as the pico-sdk's generated cyw43_arch.h, which means the sysl type-check passed.
  • pico2 and zephyr refuse the bare command by design, through their requires { headers } clause.
  • Not swept, being kernel or board repos that need a toolchain or SDK this machine does not have: picokit, ogol-pico, ogol-pico2, solder-pico2, zephyr-demo, pico-scratch. Also not swept, being infrastructure: sysl-bootstrap, sysl (the self-hosted compiler), sysl.sh, homebrew-tap, github-profile and svd.
• Outside the org, slate: a clean clone of slate-language/slate at dev (c359e6b, 0.1.14). With the tarball's binary, sysl test . passes 2,436 tests with 0 failures, and both sysl build . and sysl build . --features webview (the desktop edition) build.