v0.5.0

[0.5.0] - 2026-07-13

This release completes the split of the former monorepo into independent repos.
mux-compiler is now the canonical "Mux version" and resolves/reports the runtime
version independently; the runtime, website, playground API, and syntax
highlighting each live in and version from their own repos. Requires
mux-runtime 0.5.0.

Added

• Where-clause constraints: where { expr, ... } attaches runtime constraints to
  functions, methods, lambdas, interface methods, enum variants, fields, and classes.
  Provable violations are compile errors (zero-false-positive); the runtime panic is the
  fallback. Closes #224 (#235).
• Reject provable runtime panics at compile time: The compiler now turns provable
  runtime panics into compile-time errors, using the zero-false-positive const-fold path.
  Closes #238.
• cargo bench harness (criterion): Compiler-phase benchmarks (lex, parse, semantics,
  codegen, end-to-end pipeline) run over the whole compiling test_scripts corpus, plus
  end-to-end execution throughput benchmarks for a curated set of compiled workloads. A
  stdlib-only scripts/bench-report.py aggregates the per-file medians into a box-and-whisker
  per phase. Benchmarks are local/manual and a non-blocking CI report, never a merge gate.
  Closes #247.
• Valgrind memory checking: CI now runs compiled programs and the compiler under Valgrind
  (Memcheck), gating on definite/indirect leaks and memory errors with checked-in suppressions
  for benign third-party noise. Closes #246.
• Range-literal syntax diagnostic: A targeted diagnostic for a digit followed by ..
  (range-literal syntax) replaces the previous generic parse error. Closes #245.
• Independent runtime version resolution: The compiler resolves and reports the runtime
  version independently of its own version, so mux --version reports both (e.g.
  mux 0.5.0 (runtime 0.5.0)).

Changed

• Repo split from the monorepo: Extracted the runtime, website, playground API, and syntax
  highlighting into their own repos; removed the root VERSION file and sync-version tooling;
  scoped the SonarCloud analysis to the compiler; and rebound the project identity to
  muxlang/mux-compiler. Internals documentation now points at muxlang/mux-context.
• CLI polish: Colored diagnostics, styled help output, doctor glyphs, a version banner, and
  a compile spinner. Closes #249.
• Runtime panic documentation and behavior updated (#225, #230).
• Removed ad-hoc perf tooling: Deleted scripts/measure-baseline.sh,
  scripts/check-timings.py, and the orphaned infra/ci/baselines/*.json timing budgets, and
  stripped the unused --timings-file plumbing from run-checks.sh / integration-checks.sh.
  Also removed the unused cargo-fuzz setup under mux-compiler/fuzz/.
• Slimmed the README to a real README and pointed internals at muxlang/mux-context.

Fixed

• mux build / mux run now fail on link errors: A failed clang link previously printed
  the error but exited 0 (build reported success with no executable; run could fall through
  and execute a stale binary from a prior build). report_clang_output_or_exit now exits
  non-zero as its name implies.
• Reference-counting correctness: Reference-count cleanup for owned temporaries plus
  init/copy correctness fixes (#253); closures are now allocated with a reference-count header.
  Closes #250 (#252).
• Collection read-path performance and correctness: Fixed O(n^2) indexed reads,
  runtime-cache staleness, and Python-style negative indexing on collection reads
  (#256, #258, #259, #260).
• match usable as a statement: match now works as a statement and the guarded-arm
  exhaustiveness hole is closed (#233, #234, #243) (#242).
• Trailing commas: Allow trailing commas before newline-closed collection delimiters (#244).
• Enum codegen: Load enums from boxed pointers correctly in codegen (#237).
• Release checksum verification: Verify release checksums by hash, not path.

Security

• cmov 0.5.3 -> 0.5.4: Bumped to fix GHSA-3rjw-m598-pq24 (#254).