Option<T> / Result<T,E>: structural named-tuple via [template_tuple]

[borisbat]

Summary

Fixes #2598. Combining daslib/clargs and modules/dasSQLITE/daslib/sqlite_boost (directly or via require ... public chains) made every Option<string> ambiguous — [template_structure] cloned an instance struct into each consuming module via qmacro_template_class, producing N module-aliased views of the same source decl. Candidate collection treated them as distinct and emitted error[30341]: too many matching functions or generics _::Option<string> with three identical-looking candidates pointing at the same line.

Rather than a typer-side dedupe of candidates by source decl (broader scope, not gated on this PR), Option and Result now resolve to structural named tuples. Tuples have no module home; multiple transitive re-exports collapse to one canonical tTuple TypeDecl regardless of which alias the user lands on.

[template_tuple(T)]
struct template Option {
    _has_value : bool = false
    @safe_when_uninitialized _value : T
}

• Option<T> → tuple<_has_value : bool; _value : T>
• Result<T,E> → tuple<_is_ok : bool; _value : T; _error : E>

Pieces

daslib/typemacro_boost.das — new [template_tuple(T...)] [structure_macro]. At apply time it generates a [typemacro_function]; at typemacro-execution time the body has two paths:

• generic: shape-matches a tTuple by argNames + literal-field baseType, and feeds template-arg fields into infer_template_types via passArgument.argTypes[i].
• concrete: looks up the source struct via typeinfo ast_typedecl(type<X>) (X = the struct's module-scoped alias) and applies templates_boost's existing TypeDecl visitor (apply_template + replaceTypeWithTypeDecl) to each field. The visitor walks T, array<T>, tuple<int; T; E>, etc. uniformly — no apply-time recursion over field shapes is needed.

Field-level @safe_when_uninitialized propagates: when a source field carries the annotation, the corresponding tuple element's TypeDecl gets TypeDeclFlags.safeWhenUninitialized. The tuple's recursive unsafeInit walks its argTypes, so per-element marking gives the same effect the legacy struct-level [safe_when_uninitialized] used to.

daslib/option.das, daslib/result.das — collapse to near-original struct declarations with annotation swap + move_some / move_ok / move_err rewrites that drop the typedef RT shorthand in favor of anonymous named-tuple construction.

Compiler-side support for safe-when-uninitialized at TypeDecl granularity:

• TypeDecl::safeWhenUninitialized flag bit + unsafeInit short-circuit. Lets a typemacro mark a tuple component (e.g. Option's _value field) safe to leave uninitialized even when the underlying T isn't.
• TypeDecl::applyAutoContracts OR-merges the new flag the same way it merges ref / constant / temporary, so generic resolution preserves it across auto.
• TypeDeclFlags exposes the bit to daslang code.
• InferTypes::preVisit(ExprAssume*) silently dedupes assume X : T when an outer scope already binds X to the same type. Handles the auto-injected assume placed at the start of a generic instance body when a typemacro-built result type carries an alias the body also references. InferTypes::visit(ExprAssume*) mirrors the same predicate so a deduped re-assume is also kept out of assumeType, leaving findAlias lookups clean.
• AOT codegen: emit local make-struct destinations without const. Aggregate types holding TTuple<> need to be value-init'd at declaration; the const qualifier was making C++ reject T const x; for those shapes.

dasSQLITE adapter rail — is_option_field_type / unwrap_option_payload_type detect the typeMacro form (during [sql_table] apply) and the post-instantiation tTuple form. The legacy struct-shape detection drops out — no in-tree code emits a struct-shaped Option after this PR.

Test plan

• daslang dastest/dastest.das -- --test tests/option/ → 205/205 pass
• daslang dastest/dastest.das -- --test tests/dasSQLITE/ → 771/771 pass
• daslang dastest/dastest.das -- --test tests/ → 7961/7961 interpreted
• test_aot.exe -use-aot dastest/dastest.das -- --use-aot --test tests/ → 7355/7355 AOT
• Issue Type-macro instantiations from publicly-re-exported templates collide across modules: Option<string> ambiguous when both daslib/clargs and sqlite/sqlite_boost are in scope #2598 repro (require daslib/clargs + require sqlite/sqlite_boost + Option<string> field) compiles cleanly
• Bare-var regression: removing @safe_when_uninitialized from _value : T and recompiling tests/option/test_option_unsafe_uninitialized.das produces error[31016] on the bare var x : Option<Brittle> line — the per-field annotation is doing real work
• Composite literal field types (array<T>, tuple<int; T; E>) substitute correctly via the visitor — verified with a hand-rolled [template_tuple] probe carrying array<T> and tuple<int; T; E> field shapes
• Lint clean on all changed .das files
• MCP format_file clean on all changed .das files

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR addresses daslang generic candidate ambiguity when Option<T>/Result<T,E> templates are publicly re-exported through multiple module chains (issue #2598) by switching them from module-owned [template_structure] instances to structural named tuples produced by a new [template_tuple] structure macro. It also adds compiler/runtime support so tuple elements can carry @safe_when_uninitialized behavior, and updates dependent tooling (dasSQLITE + AOT) plus regression tests.

Changes:

• Add [template_tuple] in daslib/typemacro_boost.das to synthesize typemacro-based named tuple types (structural identity, no per-module cloning).
• Convert daslib/option.das and daslib/result.das to structural tuple forms, with per-element @safe_when_uninitialized propagation via a new TypeDecl::safeWhenUninitialized flag.
• Update compiler/AOT + dasSQLITE Option-shape handling and add regression tests for cross-module Option usage and unsafe-uninitialized payloads.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/option/test_option_user_struct.das	New regression test ensuring Option<UserStruct> works across module boundaries and remains unambiguous.
tests/option/test_option_unsafe_uninitialized.das	New regression test validating Option<T> payload field safety for “unsafe when uninitialized” payload structs.
tests/option/_test_option_user_struct_mod.das	Test helper module that publicly re-exports daslib/option and returns Option<Foo> to exercise cross-module typing.
src/builtin/module_builtin_ast_flags.cpp	Exposes new TypeDeclFlags.safeWhenUninitialized bit to daslang code.
src/ast/ast_typedecl.cpp	Propagates safeWhenUninitialized through auto contracts; short-circuits unsafeInit when the flag is set.
src/ast/ast_infer_type.cpp	Allows silent dedupe of type-only assume X : T when the same alias already resolves to the same type.
modules/dasSQLITE/daslib/sqlite_boost.das	Updates Option detection/unwrapping logic to recognize the new structural tuple shape.
include/daScript/ast/ast_typedecl.h	Adds TypeDecl::safeWhenUninitialized flag bit.
daslib/typemacro_boost.das	Implements the new [template_tuple] structure macro and per-field safe-when-uninitialized propagation.
daslib/result.das	Converts Result<T,E> to [template_tuple] + updates constructors/move helpers for tuple construction.
daslib/option.das	Converts Option<T> to [template_tuple] + updates move_some to construct tuples directly.
daslib/aot_cpp.das	Adjusts AOT local make-struct destination type emission to skip const to satisfy aggregate initialization constraints.

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.