feat(slang): cast function call arguments to match parameter types

[hedgar2017]

Store declared parameter types in function signatures and emit sol.cast for each argument whose type differs from the callee's declared parameter type. This matches the C++ reference behavior where genRValExpr receives a target type and casts accordingly.

Also cleans up inline melior:: fully-qualified paths across solx-slang by adding proper use imports for Context, BlockRef, Value, Block, Region, and IntegerType.

[Copilot]

Pull request overview

This PR updates Sol dialect lowering to record full function parameter types in the MLIR context and uses those declared types at call sites to cast arguments so sol.call operand types match the callee signature (aligning more closely with solc’s “target type” rvalue emission behavior). It also simplifies several melior:: fully-qualified references by adding local use imports.

Changes:

• Store declared parameter types (not just arity) in solx-mlir::Context function signatures and return them from resolve_function.
• In call lowering, cast each argument to the callee’s declared parameter type before emitting sol.call.
• Clean up melior:: path usage by importing Context, BlockRef, Value, Block, and Region where needed.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
solx-slang/src/ast/contract/mod.rs	Pre-registers parameter MLIR types (not just counts) for later call-site casting.
solx-slang/src/ast/contract/function/statement/control_flow.rs	Uses Block/Region imports to reduce fully-qualified references.
solx-slang/src/ast/contract/function/mod.rs	Uses imported BlockRef/Value types for clarity; no behavioral change here.
solx-slang/src/ast/contract/function/expression/operator.rs	Uses imported melior::Context in operator emission signature.
solx-slang/src/ast/contract/function/expression/call/type_conversion.rs	Uses imported Context/BlockRef/Value; keeps conversion logic centralized.
solx-slang/src/ast/contract/function/expression/call/mod.rs	Adds argument casting prior to emitting sol.call.
solx-mlir/src/context/mod.rs	Stores parameter types in signatures and returns them from resolve_function.
solx-mlir/src/context/function.rs	Updates Function metadata to store parameter_types: Vec<Type>.

[abinavpp]

It looks like resolve_function maintains a name-to-MLIR-def map to resolve callees during call codegen. This seems fragile - matching by name + argument types reimplements overload resolution that the frontend should have already done. Does Slang provide a way to resolve the callee directly from the call expression (something like a resolve_to_definition() on the callee operand)?

If it does, we should map the resolved AST definition to its MLIR op, keyed by something unique to the definition node (like its node ID), rather than doing string-based lookup.

[hedgar2017]

@abinavpp that makes total sense, and I want to do this migration. But this PR's job is only emitting the casts.
The lookup change is orthogonal to that and doesn't remove the cast work.

Happy to fold it in here or do it as a follow-up. What do you prefer?