bugfix(syntax): fix numeric_value_and_suffix to handle compound suffixes; error on typed literals in consteval_int and test attrs. - #9927

Summary

Replaces numeric_value_and_suffix returning Option<(BigInt, Option<SmolStrId>)> with a direct (BigInt, Option<SmolStrId>) return type. The new implementation scans _-separated segments from right to left, finding the longest valid numeric prefix and treating the remainder as the suffix. This correctly handles compound suffixes like 1_u32_u8 (returning value 1 with suffix "u32_u8") and ambiguous radix cases like 0x1_f32 (parsed as hex 0x1F32 with no suffix). Malformed literals such as 0x_u32 return (BigInt::ZERO, Some(full_token_text)) as a sentinel.

Callers that previously used .unwrap_or_default() now receive the value directly and check suffix.is_some() to detect errors. The consteval_int macro and available_gas test attribute now emit explicit diagnostics when a typed (suffixed) literal is used where only plain integers are valid.

Type of change

Please check one:

• Bug fix (fixes incorrect behavior)
• New feature
• Performance improvement
• Documentation change with concrete technical impact
• Style, wording, formatting, or typo-only change

Why is this change needed?

The previous rsplit_once('_') approach only split at the last _, so compound suffixes like 1_u32_u8 were mishandled — u32_u8 was not recognized as a suffix, and the numeric parse would silently fail or return a wrong value via unwrap_or_default(). Additionally, callers that used unwrap_or_default() would silently swallow parse failures rather than surfacing them as diagnostics.

What was the behavior or documentation before?

numeric_value_and_suffix returned Option<(BigInt, Option<SmolStrId>)>, splitting only at the rightmost _. Compound suffixes like 1_u32_u8 were not correctly identified. Callers used .unwrap_or_default(), silently producing 0 on failure. The consteval_int macro and gas-value extraction did not emit diagnostics for typed literals.

What is the behavior or documentation after?

numeric_value_and_suffix returns (BigInt, Option<SmolStrId>) directly, scanning from right to left across all _ boundaries to find the longest valid numeric prefix. Compound suffixes are correctly extracted. The consteval_int macro emits "Literals with suffix are not supported in consteval_int macro" and available_gas emits "Literals with suffix are not supported as gas values" when a suffixed literal is encountered.

Related issue or discussion (if any)

Fixes #9926

Additional context

New test cases cover 1_u32_u8 and -1_u32_u8 for compound suffixes in literal parsing, and consteval_int!(1_u32) / consteval_int!(1_u32 + 2) for typed literals inside the consteval_int macro.