Dea/L0 1.1.0: safer control flow and a frontend that keeps going

Updated 2026-07-21: Clarified the PAR-0243 case-arm ambiguity and the practical effects of the cleanup and drop fixes.

I have released Dea/L0 1.1.0, a focused update to the self-hosted foundation of the Dea systems programming language. This release makes control-flow cleanup safer, lets the frontend recover from more source errors, and improves the portability of the Stage 2 compiler without expanding the command-line or standard-library surface.

One spelling for the path forward

The canonical default arm for case is now _ =>:

case (status) {
    0 => printl_s("ready");
    1 => printl_s("busy");
    _ => printl_s("unknown");
}

The wildcard mirrors match and makes the default arm explicit in the same way as every other arm. Existing L0 code using case ... else still compiles in 1.1.0, but it emits the PAR-0242 deprecation warning. Removing that spelling is reserved for L0 2.0.0, giving users a full minor-release migration window.

While the old spelling remains accepted, one form is ambiguous:

1 => if (ready) start();
else wait(); // `if` branch or `case` default?

1 => { if (ready) start(); }
else wait(); // unambiguously the `case` default

PAR-0243 is limited to the first pattern: an unbraced if used as a case value-arm body and immediately followed by else. Brace the value arm as shown, or migrate the default to _ =>. The known L0 corpus contains no occurrences of this ambiguity, and 1.1.0 does not add an automatic rewrite mode.

A frontend that keeps going

A compiler is much more useful when one bad character does not erase the structure that follows it. Lexer errors can now carry a logical recovery token, so the parser can diagnose the invalid input and continue through the surrounding declaration or statement. That reduces cascades and exposes more genuine errors in one compiler run.

Diagnostic positions are more consistent too. Columns now count Unicode code points in both compiler stages, while the source contract clearly separates UTF-8 source text from the language vocabulary: strings and comments may contain Unicode, but identifiers remain ASCII. Orphaned else and cleanup keywords also receive more precise errors, and duplicate imports no longer flood the warning output.

Safer control flow and ownership

This release hardens the paths where control flow and deterministic cleanup meet. for headers, loop liveness, and unreachable-code analysis now agree across Stage 1 and Stage 2. An abrupt return, break, or continue from an inline with header now runs its paired cleanup; previously that cleanup could be skipped. A with cleanup that always returns now satisfies definite-return analysis instead of causing a false missing-return diagnostic.

For a value with ARC-managed fields, drop now validates the pointer before generated field cleanup dereferences it. Previously, a stale alias could segfault during that cleanup; it now stops with the defined drop: pointer not allocated by 'new' software failure.

The for grammar is also enforced more precisely. A let declaration in the update clause now reports PAR-0145; move the declaration outside the update clause and leave a non-declaration simple statement there.

A steadier self-hosted compiler

Stage 2 now surfaces warnings in build, run, generated-C, symbol, and type modes instead of silently dropping them in some paths. Host C compiler options are ordered correctly, Dea environment activation is stackable, and nested test environments are isolated from compiler runs.

Portability work covers Unicode test input on Windows and Apple Silicon triple-bootstrap comparisons. Mach-O UUID normalization removes a platform-specific source of noise while preserving the fixed-point checks that matter.

What stays stable, and what comes next

Dea/L0 1.1.0 adds no CLI flags or modes and adds or removes no public L0 types. The L0 standard-library implementation is unchanged. The release instead concentrates on correctness, diagnostics, and confidence in the self-hosted toolchain.

The main migration for a future major release is already visible: replace case ... else defaults with _ =>. L0 2.0.0 can then remove the deprecated spelling and its temporary ambiguity diagnostic without surprising 1.x users.

Download the four platform builds, API documentation, and checksums from the Dea/L0 1.1.0 release. The full comparison and contributor guide are available in the public repository.