[mlir][Sol] Make sol.revert's signature attribute optional

[PavelKopyl]

NomicFoundation/solx-solidity#169

Distinguish revert() and revert(""). Lower revert("") to an ABI-encoded Error(""), while lowering revert() to a bare revert(0, 0).

[Copilot]

Pull request overview

This PR updates the Sol dialect sol.revert operation to make its signature attribute optional, allowing the IR to represent plain revert() distinctly from revert(""), and adapts the Sol→Yul lowering accordingly.

Changes:

• Make sol.revert’s signature an OptionalAttr<StrAttr> and adjust the textual assembly format to allow omission.
• Update RevertOpLowering to treat “absent signature” as revert() and “present (even empty) signature” as revert("reason").

Reviewed changes

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

File	Description
mlir/lib/Conversion/SolToYul/SolToYul.cpp	Updates sol.revert lowering to handle optional signatures and preserve the empty-reason vs no-reason distinction.
mlir/include/mlir/Dialect/Sol/SolOps.td	Makes signature optional for sol.revert and updates the op’s assembly format/documentation accordingly.

Comments suppressed due to low confidence (1)

mlir/include/mlir/Dialect/Sol/SolOps.td:545

• There are currently no MLIR/lit tests covering sol.revert parsing/printing or the semantic distinction between revert(), revert(""), and revert("reason"). Since this PR changes the textual assembly format and the meaning of an absent vs empty signature, adding a round-trip test would help prevent regressions.

  let arguments = (ins Variadic<AnyType>:$args,
                       OptionalAttr<StrAttr>:$signature, UnitAttr:$call);

  let assemblyFormat = "($signature^)? ($args^ `:` type($args))? attr-dict";
}

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[abinavpp]

lgtm, thank you!