fix: support dynamic fields in event signatures

[cburgdorf]

Motivation

Fe already provides Solidity ABI types such as Bytes, DynString, and DynArray<T>, but they could not be used reliably as non-indexed event fields.

For example:

#[event]
struct ValuesChanged {
    values: DynArray<u256>,
}

This should produce the Solidity event signature:

ValuesChanged(uint256[])

and ABI-encoded event data containing:

offset(0x20) | array length | array elements

Before this change:

• DynArray event fields failed to compile because event signature generation could not derive their canonical Solidity type.
• A single dynamic field was encoded without its ABI offset head, producing malformed event data.
• Imported aliases such as DynArray as Values were not resolved reliably.
• Nested types such as DynArray<[u256; 2]> could not produce the canonical uint256[2][] signature.
• Some failures while evaluating generated TOPIC0 constants could surface as compiler ICEs instead of diagnostics.

What changed

• Add composable SolCompat implementations for dynamic and fixed-size arrays.

• Generate event signature fragments through qualified SolCompat resolution:

  • aliases resolve to the underlying core type;
  • user-defined types named DynArray retain their own implementation;
  • nested array types produce their canonical Solidity spelling.

• Encode all non-empty event data as a tuple through encode_event_payload.

  • This preserves the ABI head for a single dynamic field.
  • Static singleton fields retain their existing wire representation.

• Detect unsupported indexed dynamic fields from their resolved semantic type.

• Report generated TOPIC0 CTFE and semantic-constant reification failures as compiler diagnostics instead of panicking.

Result

Non-indexed dynamic event fields now compile and emit Solidity-compatible topics and data:

TOPIC0 = keccak256("ValuesChanged(uint256[])")
data = offset(0x20) | length | elements

Indexed dynamic fields remain unsupported for now, but produce a targeted diagnostic rather than failing indirectly.

Test coverage

Added regression coverage for:

• Bytes and DynString event fields.
• DynArray and DynArray.
• Events mixing dynamic and static fields.
• A single dynamic field with the required ABI offset head.
• DynArray<[u256; 2]> producing uint256[2][].
• Imported DynArray aliases.
• User-defined generic types also named DynArray.
• Indexed dynamic-field diagnostics through aliases.
• Generated TOPIC0 CTFE failures.
• Runtime semantic-constant reification failures.

[cburgdorf]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 539cd703e2

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[cburgdorf]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: bc984b6764

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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[cburgdorf]

@sbillig This one is ready for human review